Subject: Re: Mb problem From: Stephen & Kathy skmort@.......... Date: Thu, 31 Mar 2005 12:01:52 -0800 Thank you very much,,, works great,,, exactly what I ordered,, HA!!! Stephen 38.828N 120.979W John or Jan Lahr wrote: > Stephen, > > I've updated the page on mb: http://jclahr.com/science/software/mb/ > > It now includes the source and compiled code for computing magnitude via > the Q table > used by NEIC as well as by the formula given by Larry Braile. > > There is a link to the graph by Gutenberg and Richter (1956) which is > the basis > for the Q table. > > Cheers, > John > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Lehmann From: 1goss@........... Date: Sat, 02 Apr 2005 01:21:18 +0000 I have built a Lehmann seismorraph using the 1/2 pipe and using the pipe union for a pivot point. My question is when setting the period for the 30 inch boom.Is that from left to right then back to left if this is the case I am only getting to about 10 sec also should the boom be level. Should the gate effect take care of the swing back to center. It has been about 4 years since I built the last one and I dont remember having so much truble setting it thanks Bryan S Goss
I have built a Lehmann seismorraph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom.Is that from left to right then back to left if this is the case I am only getting to about 10 sec also should the boom be level. Should the gate effect take care of the swing back to center.

It has been about 4 years since I built the last one and I dont remember having so much truble setting it
thanks Bryan S Goss

Subject: Re: Lehmann From: ChrisAtUpw@....... Date: Fri, 1 Apr 2005 20:56:14 EST In a message dated 02/04/2005, 1goss@........... writes: > I have built a Lehman seismograph using the 1/2 pipe and using the pipe > union for a pivot point. > My question is when setting the period for the 30 inch boom. Is that from > left to right then back to left if this is the case I am only getting to about > 10 sec also should the boom be level? Should the gate effect take care of > the swing back to centre. Hi Bryan, The period is for a complete oscillation, say from when it is central, to one extreme, to the other extreme and then back again to the centre. The base levelling screws should be set up so that the pendulum comes back to the central position. The boom itself does not have to be level. It is the small angle between the true vertical and the line joining the top and bottom pivot points which is critical. You can make a good bottom pivot using a ball bearing. See Frank Cooper and John Cole http://pages.prodigy.net/fxc/ and http://pages.prodigy.net/fxc/JC.html It is quite easy to make a magnetic damper with 4 NdFeB magnets and an Al or Cu plate. Regards, Chris Chapman In a message dated 02/04/2005, 1gos= s@........... writes:

I have built a Lehman seismogra= ph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom. Is that from l= eft to right then back to left if this is the case I am only getting to abou= t 10 sec also should the boom be level? Should the gate effect take care of=20= the swing back to centre.


Hi Bryan,

       The period is for a complete oscillatio= n, say from when it is central, to one extreme, to the other extreme and the= n back again to the centre. The base levelling screws should be set up so th= at the pendulum comes back to the central position.

       The boom itself does not have to be lev= el. It is the small angle between the true vertical and the line joining the= top and bottom pivot points which is critical.

       You can make a good bottom pivot using=20= a ball bearing. See Frank Cooper and John Cole http://pages.prodigy.net/fxc/ and http://pages.prodigy.net/fxc/JC.html

       It is quite easy to make a magnetic dam= per with 4 NdFeB magnets and an Al or Cu plate.

       Regards,

       Chris Chapman

Subject: Re: Lehmann From: 1goss@........... Date: Sat, 02 Apr 2005 02:16:13 +0000 Thanks for the reply Chris I will post pictures when I get it all going. Bryan S Goss In a message dated 02/04/2005, 1goss@........... writes: > I have built a Lehman seismograph using the 1/2 pipe and using the pipe > union for a pivot point. > My question is when setting the period for the 30 inch boom. Is that from > left to right then back to left if this is the case I am only getting to about > 10 sec also should the boom be level? Should the gate effect take care of > the swing back to centre. Hi Bryan, The period is for a complete oscillation, say from when it is central, to one extreme, to the other extreme and then back again to the centre. The base levelling screws should be set up so that the pendulum comes back to the central position. The boom itself does not have to be level. It is the small angle between the true vertical and the line joining the top and bottom pivot points which is critical. You can make a good bottom pivot using a ball bearing. See Frank Cooper and John Cole http://pages.prodigy.net/fxc/ and http://pages.prodigy.net/fxc/JC.html It is quite easy to make a magnetic damper with 4 NdFeB magnets and an Al or Cu plate. Regards, Chris Chapman In a message dated 02/04/2005, 1gos= s@........... writes:

I have built a Lehman seismogra= ph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom. Is that from l= eft to right then back to left if this is the case I am only getting to abou= t 10 sec also should the boom be level? Should the gate effect take care of=20= the swing back to centre.


Hi Bryan,

       The period is for a complete oscillatio= n, say from when it is central, to one extreme, to the other extreme and the= n back again to the centre. The base levelling screws should be set up so th= at the pendulum comes back to the central position.

       The boom itself does not have to be lev= el. It is the small angle between the true vertical and the line joining the= top and bottom pivot points which is critical.

       You can make a good bottom pivot using=20= a ball bearing. See Frank Cooper and John Cole http://pages.prodigy.net/fxc/ and http://pages.prodigy.net/fxc/JC.html

       It is quite easy to make a magnetic dam= per with 4 NdFeB magnets and an Al or Cu plate.

       Regards,

       Chris Chapman

Subject: Re: Lehmann From: John or Jan Lahr JohnJan@........ Date: Fri, 01 Apr 2005 20:04:39 -0700 Hi Bryan, The period is measured over one complete swing, from left to right and back again. It's not easy to get a period greater than about 15 seconds. If the connection between the mast and the base has the least amount of flex, then the mast will bend very slightly toward the boom. The symptom of this is that the boom will tend to swing to one side or the other rather than finding a stable center position when the period is adjusted to be very long. Cheers, John At 06:21 PM 4/1/2005, you wrote: >I have built a Lehmann seismorraph using the 1/2 pipe and using the pipe >union for a pivot point. >My question is when setting the period for the 30 inch boom.Is that from >left to right then back to left if this is the case I am only getting to >about 10 sec also should the boom be level. Should the gate effect take >care of the swing back to center. > >It has been about 4 years since I built the last one and I dont remember >having so much truble setting it >thanks Bryan S Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Got it going I think From: 1goss@........... Date: Sat, 02 Apr 2005 22:11:28 +0000 I got my Lehman Seismometer up and running I think I may have my gain set a bit high, But I think it is ok. let me know if it looks ok, I am just waiting on an event. My setup is a remote computer in my shop about 200ft away. linked to high speed internet via 2.4 gig network connection. From there to my comcast cable then to you I purchased Larrys 16-Bit Serial Output A/D Board for WinSDR with GPS and it is working great. Thanks for the help on setting the boom period I got it to about 12 sec. THE LINK https://home.comcast.net/~bryangoss/ch1.gif __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Got it going I think From: ChrisAtUpw@....... Date: Sat, 2 Apr 2005 19:37:10 EST In a message dated 02/04/2005, 1goss@........... writes: > I got my Lehman Seismometer up and running I think I may have my gain set a > bit high, But I think it is ok. HI Bryan, It looks like you have a fairly high gain on the amplifier. I suggest that you examine sections of the trace, do a FFT on it and check to see if the ~six second ocean background is dominant or if there is a lot of other noise. Try wedging the mass so that it can't move to check on instrument noise? I can't tell much from the drumplot, since I don't know how it was scaled. It doesn't show any waveforms or any peak counts. You need to click on X-Scale at the top of the display and then select 'counts'. The display shows small deflections during the night, but much larger ones during the 'working day'. Do you have a lot of traffic / industrial noise? What sort of suspensions / bearings are you using? A 12 sec plot doesn't give you much 'headroom' over the 6 sec microseisms. Regards, Chris Chapman In a message dated 02/04/2005, 1gos= s@........... writes:

I got my Lehman Seismometer up=20= and running I think I may have my gain set a bit high, But I think it is ok.=


HI Bryan,

       It looks like you have a fairly high ga= in on the amplifier. I suggest that you examine sections of the trace, do a=20= FFT on it and check to see if the ~six second ocean background is dominant o= r if there is a lot of other noise. Try wedging the mass so that it can't mo= ve to check on instrument noise? I can't tell much from the drumplot, since=20= I don't know how it was scaled. It doesn't show any waveforms or any peak co= unts. You need to click on X-Scale at the top of the display and then select= 'counts'.
       The display shows small deflections dur= ing the night, but much larger ones during the 'working day'. Do you have a=20= lot of traffic / industrial noise?

       What sort of suspensions / bearings are= you using? A 12 sec plot doesn't give you much 'headroom' over the 6 sec mi= croseisms.

       Regards,

       Chris Chapman
Subject: Re: Got it going I think From: BOB BARNS royb1@........... Date: Sat, 02 Apr 2005 20:46:56 -0500 Hi, My suggestion for setting the gain is to set it for just a few counts from the A/D on a very quiet day. Bob Barns ChrisAtUpw@....... wrote: > In a message dated 02/04/2005, 1goss@........... writes: > >> I got my Lehman Seismometer up and running I think I may have my gain >> set a bit high, But I think it is ok. > > > > HI Bryan, > > It looks like you have a fairly high gain on the amplifier. I > suggest that you examine sections of the trace, do a FFT on it and check > to see if the ~six second ocean background is dominant or if there is a > lot of other noise. Try wedging the mass so that it can't move to check > on instrument noise? I can't tell much from the drumplot, since I don't > know how it was scaled. It doesn't show any waveforms or any peak > counts. You need to click on X-Scale at the top of the display and then > select 'counts'. > The display shows small deflections during the night, but much > larger ones during the 'working day'. Do you have a lot of traffic / > industrial noise? > > What sort of suspensions / bearings are you using? A 12 sec plot > doesn't give you much 'headroom' over the 6 sec microseisms. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: pictures help From: 1goss@........... Date: Sun, 03 Apr 2005 03:57:29 +0000 This is a screenshot of WinSDR It shows the 6 sec microseisms I think? https://home.comcast.net/~bryangoss/winsdr.jpg This is the boom pivot point a pipe union and razor blade https://home.comcast.net/~bryangoss/pipeunion.jpg This is the damping https://home.comcast.net/~bryangoss/damping.jpg The bolt and 25mm wire https://home.comcast.net/~bryangoss/boltwire.jpg The 5lb weight and coil https://home.comcast.net/~bryangoss/coil.jpg The overall I put the Seismograph in a clear box to prevent draft bit I need to seal off the bottom this picture shows entire system and my messy shop!!!!! https://home.comcast.net/~bryangoss/overall.jpg https://home.comcast.net/~bryangoss/setup.jpg Chris I am not sure how to do the FFT. I hope the screenshot of winsdr will help, Thanks for the help If you all see somthing to improve I will try to do it. is the ball bearing better than the razer blade? Thanks Very Much Bryan S Goss Corinth MS __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: boom pivot From: Angel sismos@.............. Date: Sun, 3 Apr 2005 04:52:16 -0500 Bryan, Congratulations and thanks for all the pictures, they help. I really think that you can with very little more work you can greatly improve the pivot. There are several ways to make the pivot better, the ball bearing is a good and easy way. I have used wire pivot which is harder make especially after the fact, here are some pictures. www.volcanbaru.com/gardengate The Winquake software you are using will allow you to do an FFT. regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: boom pivot From: Dave Nelson davenn@............... Date: Sun, 03 Apr 2005 20:06:35 +1000 >www.volcanbaru.com/gardengate >The Winquake software you are using will allow you to do an FFT. >regards, >Angel good pics Angel, the last pic is missing though, maybe u forgot to load that one up to ur www site :) I see u are using a similar principle to the wire pivot used in the long period seismometer by the Worldwide Standard Seismic Network I used one of those seismo's back in New Zealand and it was VERY successful. One of the Denver area PSN'ers also has one think that was John Lahr :) cheers Dave N Sydney __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: pictures help From: Dave Nelson davenn@............... Date: Sun, 03 Apr 2005 20:11:24 +1000 Excellent work Bryan, great to see another amateur station getting up and running on behalf of the PSN I would like to invite you to submit your station information to me so I can include you on the PSN station map visit my pages at http://www.sydneystormcity.com/map.htm and below the world map you sill see a list of the info I collect for the station info .... there you will also see that click on sections of the map or dots and find out about the other PSN stations around the world cheers Dave N Sydney __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: the warning of earthquakes From: Alexandr Yagodin midia@.............. Date: Sun, 03 Apr 2005 14:21:06 +0200 I welcome all from Haifa! I do the warning of earthquakes in Israel and near areas on distance up to 1000 - 1500 kms. For this purpose I use behaviour of animals. I have learned to test for this purpose dogs. Time of an advancing of a beginning of earthquake - not less than 20 - 40 minutes. If someone wants to participate in the warning of earthquakes - I can help with testing dogs. Yours faithfully. Alexandr Yagodin midia@..............

I welcome all from Haifa!

I do the warning of earthquakes in Israel and near areas on distance up to 1000 - 1500 kms.

For this purpose I use behaviour of animals. I have learned to test for this purpose dogs.

Time of an advancing of a beginning of earthquake - not less than 20 - 40 minutes.

If someone wants to participate in the warning of earthquakes - I can help with testing dogs.

Yours faithfully.

Alexandr Yagodin

midia@..............

 

Subject: Re: the warning of earthquakes From: Mark Robinson mark.robinson@............... Date: Mon, 04 Apr 2005 00:46:03 +1200 Hi folks, Speaking of warning of earthquakes, I made an offhand prediction that there was going to be a significant earthquake six hours or so before the 8.7 in Indonesia. This was based this on unusual long period activity on the USGS instrument in Wellington which I have associated with the run up to large quakes in the past. Strange patterns of waves of similar period to the global ringing which happens after a large quake. Perhaps some of the learned people here could tell me if this is a known phenomenon and if so point me at some reading material. Welcome to here Alexandr, I'm not aware of anyone else here working animals. All the best, regards Mark (my tsunami warning system is happening very slowly, but I do seem to get the ITIC warnings within 20 minutes of major events, when it's actually working, and they ring a bell and fire my pager) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: the warning of earthquakes From: Alexandr Yagodin midia@.............. Date: Sun, 03 Apr 2005 16:21:17 +0200 Hi, Mark! You can tell, what was speed of waves, which you measured before earthquake? Successes. Alexandr. You can use the interpreter with Russian on English? ----- Original Message ----- From: "Mark Robinson" To: Sent: Sunday, April 03, 2005 2:46 PM Subject: Re: the warning of earthquakes > Hi folks, > > Speaking of warning of earthquakes, I made an offhand prediction that > there was going to be a significant earthquake six hours or so before > the 8.7 in Indonesia. > > This was based this on unusual long period activity on the USGS > instrument in Wellington which I have associated with the run up to > large quakes in the past. Strange patterns of waves of similar period to > the global ringing which happens after a large quake. > > Perhaps some of the learned people here could tell me if this is a known > phenomenon and if so point me at some reading material. > > Welcome to here Alexandr, I'm not aware of anyone else here working animals. > > All the best, > > regards > Mark > > (my tsunami warning system is happening very slowly, but I do seem to > get the ITIC warnings within 20 minutes of major events, when it's > actually working, and they ring a bell and fire my pager) > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noise From: 1goss@........... Date: Sun, 03 Apr 2005 22:02:24 +0000 I am having problems with noise during the night. Oddly it starts about 9:00pm and ends about 11:00 am. 9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg 11:00am WinSDR screenshot https://home.comcast.net/~bryangoss/noise11am.jpg I think these pictures will explain much more than I can. I thought it could be because the shop has a concrete floor and the air in the shop heats up to aournd 70F during the day and cools to around 36F at night. I believe the slower cooling of the floor during the night could be causing convection in the box. I tried to seal the box off and covered it with a blanket but that did not work. Could it be caused by the temperature change in the mineral oil and the vertical dampener? I ran FFT but to be honest, I'm not sure how to read it. Thank you for any help you can offer. Bryan S. Goss In a message dated 02/04/2005, 1goss@........... writes: > I got my Lehman Seismometer up and running I think I may have my gain set a > bit high, But I think it is ok. HI Bryan, It looks like you have a fairly high gain on the amplifier. I suggest that you examine sections of the trace, do a FFT on it and check to see if the ~six second ocean background is dominant or if there is a lot of other noise. Try wedging the mass so that it can't move to check on instrument noise? I can't tell much from the drumplot, since I don't know how it was scaled. It doesn't show any waveforms or any peak counts. You need to click on X-Scale at the top of the display and then select 'counts'. The display shows small deflections during the night, but much larger ones during the 'working day'. Do you have a lot of traffic / industrial noise? What sort of suspensions / bearings are you using? A 12 sec plot doesn't give you much 'headroom' over the 6 sec microseisms. Regards, Chris Chapman In a message dated 02/04/2005, 1gos= s@........... writes:

I got my Lehman Seismometer up=20= and running I think I may have my gain set a bit high, But I think it is ok.=


HI Bryan,

       It looks like you have a fairly high ga= in on the amplifier. I suggest that you examine sections of the trace, do a=20= FFT on it and check to see if the ~six second ocean background is dominant o= r if there is a lot of other noise. Try wedging the mass so that it can't mo= ve to check on instrument noise? I can't tell much from the drumplot, since=20= I don't know how it was scaled. It doesn't show any waveforms or any peak co= unts. You need to click on X-Scale at the top of the display and then select= 'counts'.
       The display shows small deflections dur= ing the night, but much larger ones during the 'working day'. Do you have a=20= lot of traffic / industrial noise?

       What sort of suspensions / bearings are= you using? A 12 sec plot doesn't give you much 'headroom' over the 6 sec mi= croseisms.

       Regards,

       Chris Chapman
Subject: Re[2]: noise From: Angel sismos@.............. Date: Sun, 3 Apr 2005 17:38:50 -0500 Bryan, Post a picture of the FFT. Do you have forced air central heating? regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: noise From: Bob Hancock Bob.Hancock@............ Date: Sun, 03 Apr 2005 15:50:22 -0700 Bryan - Not sure where you are located, but the microseisms are high right now. You can check out a Navy web site that shows ocean wave height around the world, from current, to projected wave height for 144 hours in the future. Ocean waves are a big contributor to seismic noise in the 6 to 10 second period noise. The link to web site is https://www.fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html More information can be found with the ALBUQUERQUE SEISMOLOGICAL LABORATORY (ASL) publication, OBSERVATIONS AND MODELING OF SEISMIC BACKGROUND NOISE. This can be downloaded from the following link http://aslwww.cr.usgs.gov/Publications/pdffiles/asl93-~1.pdf Another quick reference for microseisms is the Lamont-Daugherty Cooperative Seismic Network (LCSN), near New York City. Their link is http://www.ldeo.columbia.edu/cgi-bin/LCSN/WebSeis/24hr_heli.pl Hopefully these links will help you in making determinations of your seismic activity. As you can see the microseisms are high on the LCSN web site, and I am experiencing high microseisms at my location, about 30 miles west of Tucson, Arizona. Bob Hancock Tucson, AZ -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of 1goss@........... Sent: Sunday, April 03, 2005 15:02 To: psn-l@.............. Subject: Re: noise I am having problems with noise during the night. Oddly it starts about 9:00pm and ends about 11:00 am. 9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg 11:00am WinSDR screenshot https://home.comcast.net/~bryangoss/noise11am.jpg I think these pictures will explain much more than I can. I thought it could be because the shop has a concrete floor and the air in the shop heats up to aournd 70F during the day and cools to around 36F at night. I believe the slower cooling of the floor during the night could be causing convection in the box. I tried to seal the box off and covered it with a blanket but that did not work. Could it be caused by the temperature change in the mineral oil and the vertical dampener? I ran FFT but to be honest, I'm not sure how to read it. Thank you for any help you can offer. Bryan S. Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Noise FFT picture From: 1goss@........... Date: Sun, 03 Apr 2005 23:38:51 +0000 As requested by Angel: "Post a picture of the FFT. Do you have forced air central heating? regards, Angel" No I don't have any heating in the shop it is a 20 x 40 about 100 ft from my house. Here is a 10 minute clip at peak noise with WinQuake. https://home.comcast.net/~bryangoss/peak.jpg Here is the same clip FFT. I put a v where the curser was. https://home.comcast.net/~bryangoss/FFT.jpg Also Thank you all for helping the links you sent will help Bob. and as Chris sugested I may change my pivot point to a ball bering. > Bryan, > > Post a picture of the FFT. > > Do you have forced air central heating? > > regards, > > Angel > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noise From: ChrisAtUpw@....... Date: Sun, 3 Apr 2005 20:14:06 EDT In a message dated 03/04/2005, 1goss@........... writes: > I am having problems with noise during the night. Oddly it starts about > 9:00pm and ends about 11:00 am. > > 9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg Hi Bryan, This is NOT ocean background! The background is about 10 cycles per minute, so 10 mins should give ~100 peaks. > 11:00am WinSDR screenshot > https://home.comcast.net/~bryangoss/noise11am.jpg This could well be the ocean background. > I thought it could be because the shop has a concrete floor and the air in > the shop heats up to around 70F during the day and cools to around 36F at > night. I believe the slower cooling of the floor during the night could be > causing convection in the box. I tried to seal the box off and covered it with a > blanket but that did not work. Could it be caused by the temperature change in > the mineral oil and the vertical dampener? Ouch! Gee! You need to keep the temperature a lot more constant. Seal the joints of the perspex case with the special 2" clear tape that you use to make glass joins in greenhouse windows. Then get a large cardboard box, seal the top joins with 2" gaffer tape and place it over the perspex box. Get a 15 W light bulb and place it inside the top of the perspex box. This heating should keep a stable temperature gradient inside, but you should really think long term of finding somewhere which only changes temperature by a few degrees from day to night. If the cardboard box and the bulb give a significant improvement, think in terms of making a 2" thick cellotex case - see the bottom photo at http://pages.prodigy.net/fxc/ It can't be a direct effect of changes in oil viscosity, since the damping is greatest when the temperature is least and you see the opposite. I suspect that you may be correct in assuming that you have turbulent air cooling during the night. > I ran FFT but to be honest, I'm not sure how to read it. The vertical axis is the logarithmic signal amplitude. The horizontal axis is the logarithmic frequency, with higher frequencies toward the right. It will be 100, 10, 1, 0.1, 0.01, 0.001 Hz. There is a cursor on the screen which reads out in frequency and period figures at the top of the screen. Your plot shows excessive low frequency signals, which could well be associated with cooling. Regards, Chris Chapman In a message dated 03/04/2005, 1gos= s@........... writes:

I am having problems with noise= during the night. Oddly it starts about 9:00pm and ends about 11:00 am.

9:00pm WinSDR screenshot  https://home.comcast.net/~bryangoss/noise9pm.jpg


Hi Bryan,

       This is NOT ocean background! The backg= round is about 10 cycles per minute, so 10 mins should give ~100 peaks. = ;

11:00am WinSDR screenshot = https://home.= comcast.net/~bryangoss/noise11am.jpg


       This could well be the ocean background= ..

I thought it could be because t= he shop has a concrete floor and the air in the shop heats up to around 70F=20= during the day and cools to around 36F at night. I believe the slower coolin= g of the floor during the night could be causing convection in the box. I tr= ied to seal the box off and covered it with a blanket but that did not work.= Could it be caused by the temperature change in the mineral oil and the ver= tical dampener?


    Ouch! Gee! You need to keep the temperature a lot more constant. Seal the joints of the perspex case with the special 2= " clear tape that you use to make glass joins in greenhouse windows. Then ge= t a large cardboard box, seal the top joins with 2" gaffer tape and place it= over the perspex box. Get a 15 W light bulb and place it inside the t= op of the perspex box. This heating should keep a stable temperature= gradient inside, but you should really think long term of finding somewhere= which only changes temperature by a few degrees from day to night. If the c= ardboard box and the bulb give a significant improvement, think in terms of=20= making a 2" thick cellotex case - see the bottom photo at http://pages.prodigy.net/fxc/

    It can't be a direct effect of changes in oil viscosity,=20= since the damping is greatest when the temperature is least and you see the=20= opposite. I suspect that you may be correct in assuming that you have turbul= ent air cooling during the night.

I ran FFT but to be honest, I'm= not sure how to read it.


       The vertical axis is the logarithmic si= gnal amplitude. The horizontal axis is the logarithmic frequency, with highe= r frequencies toward the right. It will be 100, 10, 1, 0.1, 0.01, 0.001 Hz.=20= There is a cursor on the screen which reads out in frequency and period figu= res at the top of the screen. Your plot shows excessive low frequency signal= s, which could well be associated with cooling.

       Regards,

       Chris Chapman
Subject: Re: pictures help From: ChrisAtUpw@....... Date: Sun, 3 Apr 2005 23:25:05 EDT In a message dated 03/04/2005, 1goss@........... writes: > This is a screenshot of WinSDR It shows the 6 sec microseisms I think? > https://home.comcast.net/~bryangoss/winsdr.jpg Hi Bryan, The time scale given is four minutes. With a microseism period of ~6 sec, you should be looking at ~40 cycles total. This could fit the faster vibrations or it could all be mostly noise. There is certainly a lot of longer period stuff in with it. > This is the boom pivot point a pipe union and razor blade > https://home.comcast.net/~bryangoss/pipeunion.jpg is the ball bearing > better than the razer blade? Razor blades do not tend to last very long. The idea seems to have arisen from the old system of knife edge bearings for lab balances. These used 60 deg triangular agate bars resting on a flat agate plate. This only allowed about 200 gm load and the edge of the triangle had a tiny radius lapped onto it. A razor blade is about 15 deg and very sharp, so the edge load is huge and you are asking it to take > 2 kgm. Umm. Stainless ball bearings last for ~ever. You should be able to get >20 sec response without any problems You can buy stainless steel ball bearings ~3/16", which do not corrode. For a flat, you can use a tungsten carbide tool insert bit for a lathe. You can get flat triangular bits with about 0.3" sides, quite cheaply. If you epoxy the bearing into a V hole made with centre drill on the vertical support, turn the end of the boom rod flat and epoxy the tool bit onto this end, it should work very well. If you mount the ball in the end of the swing arm, you will have to do a major levelling operation every time you dismount the arm..... > This is the damping > https://home.comcast.net/~bryangoss/damping.jpg You shouldn't need oil AND magnetic damping! The magnet set-up you have should give both vertical and horizontal damping! I suggest that you remove the oil and then reduce the magnet separation till you get just sub-critical damping? If you can't get enough damping, use a 1/8" thick Cu plate. If you slowly deflect the arm 1/2" to one side and then release it, it should just go through zero by 1/16" or less and then fall back to zero. There are several problems with oil damping. It is very temperature sensitive, relatively difficult to set up, it is messy due to oil creep and it collects bugs - giving 'bug-quakes'! It is also 'non linear' in that it selectively damps short period motion much more than long period motion. The professionals stopped using it over 50 years ago.... I use a quad NdFeB bar magnet damping set-up. Two 1/4" thick mild steel plates 3.5" long by 2" wide are held apart by four 1/4" mild steel bolts and additional nuts at each corner. A NS pair of rectangular NdFeB magnets, 1" x 1/2" x 1/4" are placed on the centre of the face of one plate with the long axis parallel to the 2". A pair of SN magnets are placed on the opposing face of the other plate and the separation is adjusted to about 1/8" to 3/16". The central field gradient is simply huge. A 1/16" or 1/8" thick plate of soft Al or Cu about 2" wide and 3" long is mounted on the arm. It is important to make the damping plate wider than the 1" of the magnets to avoid field edge effects. The main damping is over the central 1" NS magnet joint. If you mount a L shaped Cu blade horizontally, you can just slide the magnet array further over it to increase the damping. You also reduce the damping by increasing the central magnetic gap. The stray field is low with this design. I put gaffer tape on the magnet faces and then peel it off before I assemble the two plates, to remove any magnetic debris / whiskers. You always get some and it is very difficult to see... > The bolt and 25mm wire > https://home.comcast.net/~bryangoss/boltwire.jpg > > The 5lb weight and coil > https://home.comcast.net/~bryangoss/coil.jpg If you mount the sensor magnet on the arm, it will respond to changing magnetic fields, the earth's field, power line surges, fridge motors, even to passing cars and lorries. If you mount the coil on the arm, it will be ~free of these interfering signals. You may detect movements of a few millionth's of an inch! The effective length of the arm is a bit shorter than the distance between the centre of the mass and the knife edge. You want this to be ~30 to 40" to give a long period. You might mount the mass quite a bit further along the arm? It is usual to attach the top suspension wire to a ~3" high vertical extension plate above the screw arm. This gives a small vertical pendulum effect and prevents the arm from rotating when it senses movement. This is necessary if you use a ball or wire suspension. > The overall I put the Seismograph in a clear box to prevent draft bit I > need to seal off the bottom this picture shows entire system and my messy > shop!!!!! > > https://home.comcast.net/~bryangoss/overall.jpg This looks OK, but you probably need to seal the edges of the case. You can buy 3" wide clear sticky tape for sealing greenhouse windows. This will take sunlight and it does not loose adhesion with time. Don't use cellotape, or ordinary pvc tape - they won't last long and you only want to do the job once! I would use two longitudinal L angles to support the whole base suspension, the sensor and the damping array plates. I use a single bolt at the centre of the mass end of the rig to alter the tilt angle. This makes adjustments a whole lot easier. You can set up each section / clearance in turn and the adjustments don't interact much. > https://home.comcast.net/~bryangoss/setup.jpg > I would mount the computer and monitor further away from the seismometer. You will certainly see a signal when you turn the monitor on, due to the large magnetic pulse used to demagnetise the screen. > Chris I am not sure how to do the FFT. I hope the screenshot of winsdr will > help, Thanks for the help If you all see something to improve I will try to > do it. > Thanks Very Much Bryan S Goss Corinth MS If you are using WinQuake, there is a tab labelled FFT on the top tool bar. You place the cursor where you want to start on the trace and click on. There should be a help file if you look for it. Hope that this is of some help! Are there two Corinths in MS? Regards, Chris Chapman In a message dated 03/04/2005, 1gos= s@........... writes:

This is a screenshot of WinSDR=20= It shows the 6 sec microseisms I think?
https://home.comc= ast.net/~bryangoss/winsdr.jpg


Hi Bryan,

       The time scale given is four minutes. W= ith a microseism period of ~6 sec, you should be looking at ~40 cycles total= .. This could fit the faster vibrations or it could all be mostly noise. Ther= e is certainly a lot of longer period stuff in with it.

This is the boom pivot point a=20= pipe union and razor blade
https://home.c= omcast.net/~bryangoss/pipeunion.jpg  is the ball bearing better tha= n the razer blade?


       Razor blades do not tend to last very=20= long. The idea seems to have arisen from the old system of knife edge bearin= gs for lab balances. These used 60 deg triangular agate bars resting on a fl= at agate plate. This only allowed about 200 gm load and the edge of the tria= ngle had a tiny radius lapped onto it. A razor blade is about 15 deg and ver= y sharp, so the edge load is huge and you are asking it to take > 2 kgm.=20= Umm. Stainless ball bearings last for ~ever. You should be able to get >2= 0 sec response without any problems

       You can buy stainless steel ball bearin= gs ~3/16", which do not corrode. For a flat, you can use a tungsten carbide=20= tool insert bit for a lathe. You can get flat triangular bits=20= with about 0.3" sides, quite cheaply. If you epoxy the bearing into a V hole= made with centre drill on the vertical support, turn the end of the boom ro= d flat and epoxy the tool bit onto this end, it should work very well. If yo= u mount the ball in the end of the swing arm, you will have to do a major le= velling operation every time you dismount the arm.....

This is the damping
https://home.com= cast.net/~bryangoss/damping.jpg


       You shouldn't need oil AND magnetic damping! The magnet set-up you have should give both verti= cal and horizontal damping! I suggest that you remove the oil and th= en reduce the magnet separation till you get just sub-critical damping? If y= ou can't get enough damping, use a 1/8" thick Cu plate. If you slowly deflec= t the arm 1/2" to one side and then release it, it should just go through ze= ro by 1/16" or less and then fall back to zero.
       There are several problems with oil dam= ping. It is very temperature sensitive, relatively difficult to set up, it i= s messy due to oil creep and it collects bugs - giving 'bug-quakes'! It is a= lso 'non linear' in that it selectively damps short period motion much more=20= than long period motion. The professionals stopped using it over 50 years ag= o....
       I use a quad NdFeB bar magnet damping s= et-up. Two 1/4" thick mild steel plates 3.5" long by 2" wide are held apart=20= by four 1/4" mild steel bolts and additional nuts at each corner. A NS pair=20= of rectangular NdFeB magnets, 1" x 1/2" x 1/4" are placed on the centre of t= he face of one plate with the long axis parallel to the 2". A pair of SN mag= nets are placed on the opposing face of the other plate and the separation i= s adjusted to about 1/8" to 3/16". The central field gradient is simply huge= .. A 1/16" or 1/8" thick plate of soft Al or Cu about 2" wide and 3" long is=20= mounted on the arm. It is important to make the damping plate wider than the= 1" of the magnets to avoid field edge effects. The main damping is over the= central 1" NS magnet joint. If you mount a L shaped Cu blade horizontally,=20= you can just slide the magnet array further over it to increase the damping.= You also reduce the damping by increasing the central magnetic gap. The str= ay field is low with this design. I put gaffer tape on the magnet faces and=20= then peel it off before I assemble the two plates, to remove any magnetic de= bris / whiskers. You always get some and it is very difficult to see...

The bolt and 25mm wire
https://home.comcast.net/~bryangoss/boltwire.jpg

The 5lb weight and coil
https://home.comcas= t.net/~bryangoss/coil.jpg


       If you mount the sensor magnet on the=20= arm, it will respond to changing magnetic fields, the earth's field, power l= ine surges, fridge motors, even to passing cars and lorries. If you mount th= e coil on the arm, it will be ~free of these interfering signals. You may de= tect movements of a few millionth's of an inch!

       The effective length of the arm is a bi= t shorter than the distance between the centre of the mass and the knife edg= e. You want this to be ~30 to 40" to give a long period. You might mount the= mass quite a bit further along the arm?

       It is usual to attach the top suspensio= n wire to a ~3" high vertical extension plate above the screw arm. This give= s a small vertical pendulum effect and prevents the arm from rotating when i= t senses movement. This is necessary if you use a ball or wire suspension.

The overall I put the Seismogr= aph in a clear box to prevent draft bit I need to seal off the bottom this p= icture shows entire system and my messy shop!!!!!

  https://h= ome.comcast.net/~bryangoss/overall.jpg


       This looks OK, but you probably need t= o seal the edges of the case. You can buy 3" wide clear sticky tape for seal= ing greenhouse windows. This will take sunlight and it does not loose adhesi= on with time. Don't use cellotape, or ordinary pvc tape - they won't last lo= ng and you only want to do the job once!

    I would use two longitudinal L angles to support the whol= e base suspension, the sensor and the damping array plates. I use a single b= olt at the centre of the mass end of the rig to alter the tilt angle. Thi= s makes adjustments a whole lot easier. You can set up each section / cl= earance in turn and the adjustments don't interact much.

  https://home.comcast.net/~bryangoss/setup.= jpg

   I would mount the computer and monitor further away from the s= eismometer. You will certainly see a signal when you turn the monitor on, du= e to the large magnetic pulse used to demagnetise the screen.

Chris I am not sure how to do t= he FFT. I hope the screenshot of winsdr will help, Thanks for the help If yo= u all see something to improve I will try to do it.
Thanks Very Much Bryan S Goss Corinth MS


       If you are using WinQuake, there is a t= ab labelled FFT on the top tool bar. You place the cursor where you want to=20= start on the trace and click on. There should be a help file if you look for= it.

       Hope that this is of some help! Are the= re two Corinths in MS?

       Regards,

       Chris Chapman
Subject: Re: the warning of earthquakes From: ChrisAtUpw@....... Date: Sun, 3 Apr 2005 23:35:25 EDT In a message dated 03/04/2005, mark.robinson@............... writes: > Speaking of warning of earthquakes, I made an offhand prediction that > there was going to be a significant earthquake six hours or so before > the 8.7 in Indonesia. > > This was based this on unusual long period activity on the USGS > instrument in Wellington which I have associated with the run up to > large quakes in the past. Strange patterns of waves of similar period to > the global ringing which happens after a large quake. > > Perhaps some of the learned people here could tell me if this is a known > phenomenon and if so point me at some reading material. Hi Mark, I was certainly aware of these eigenmode signals, which are a bit difficult to see on 'ordinary' seismometers, but I do not offhand know of any reports. There certainly should be some about. You can also see these effects with a really sensitive tiltmeter. Regards, Chris Chapman In a message dated 03/04/2005, mark= ..robinson@............... writes:

Speaking of warning of earthqua= kes, I made an offhand prediction that
there was going to be a significant earthquake six hours or so before
the 8.7 in Indonesia.

This was based this on unusual long period activity on the USGS
instrument in Wellington which I have associated with the run up to
large quakes in the past. Strange patterns of waves of similar period to the global ringing which happens after a large quake.

Perhaps some of the learned people here could tell me if this is a known phenomenon and if so point me at some reading material.


Hi Mark,

       I was certainly aware of these eigenmod= e signals, which are a bit difficult to see on 'ordinary' seismometers, but=20= I do not offhand know of any reports. There certainly should be some about.=20= You can also see these effects with a really sensitive tiltmeter.

       Regards,

       Chris Chapman
Subject: Re: the warning of earthquakes From: Mark Robinson mark.robinson@............... Date: Mon, 04 Apr 2005 15:49:10 +1200 ChrisAtUpw@....... wrote: > eigenmode Thanks Chris, That's what I needed. cheers Mark __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Chris improvements From: 1goss@........... Date: Mon, 04 Apr 2005 08:43:58 +0000 I would like very much to see detailed pictures of your setup. It would help me to better understand the improvements you suggested. I have 2 questions: 1. If you put the coil on the boom how do you keep the wire from interfering with the swing or period. 2 I used 3/8 all thread,as you could see. I was afraid it would bend under the weight as I noted the 4ft length of the rod was flexible when I bought it. What size rod did you use?What size should I use? oops went over 2 questions. 3 My nightmare the only place I can put the seismograph is in my shop it is very UN-level. I could not believe how much. It sets on sand near a ditch when I level the boom their is over an inch difference from one end to the other, this makes a hard job harder. I came very close during this part of setup to "making a beer run" as we say here in the south. I had considered pouring a small amount of concrete to try and fix this. also tonight late I had very little noise so it seems as their was no big temperature contrast,this may well be the bigger problem. I ran FFT on the low noise output of the seismograph and I clearly saw a spike the 6 sec microseisms. This is a good thing I right? but I am still going to improve it. I am about 20 miles from Pickwick Lake, AL In extreme northern MS. 50 miles north of Tupelo MS. Thanks so much for all your help and everyone that has contributed and please forgive my bad gram-mer oveously not one of my strong points. In a message dated 03/04/2005, 1goss@........... writes: > This is a screenshot of WinSDR It shows the 6 sec microseisms I think? > https://home.comcast.net/~bryangoss/winsdr.jpg Hi Bryan, The time scale given is four minutes. With a microseism period of ~6 sec, you should be looking at ~40 cycles total. This could fit the faster vibrations or it could all be mostly noise. There is certainly a lot of longer period stuff in with it. > This is the boom pivot point a pipe union and razor blade > https://home.comcast.net/~bryangoss/pipeunion.jpg is the ball bearing > better than the razer blade? Razor blades do not tend to last very long. The idea seems to have arisen from the old system of knife edge bearings for lab balances. These used 60 deg triangular agate bars resting on a flat agate plate. This only allowed about 200 gm load and the edge of the triangle had a tiny radius lapped onto it. A razor blade is about 15 deg and very sharp, so the edge load is huge and you are asking it to take > 2 kgm. Umm. Stainless ball bearings last for ~ever. You should be able to get >20 sec response without any problems You can buy stainless steel ball bearings ~3/16", which do not corrode. For a flat, you can use a tungsten carbide tool insert bit for a lathe. You can get flat triangular bits with about 0.3" sides, quite cheaply. If you epoxy the bearing into a V hole made with centre drill on the vertical support, turn the end of the boom rod flat and epoxy the tool bit onto this end, it should work very well. If you mount the ball in the end of the swing arm, you will have to do a major levelling operation every time you dismount the arm..... > This is the damping > https://home.comcast.net/~bryangoss/damping.jpg You shouldn't need oil AND magnetic damping! The magnet set-up you have should give both vertical and horizontal damping! I suggest that you remove the oil and then reduce the magnet separation till you get just sub-critical damping? If you can't get enough damping, use a 1/8" thick Cu plate. If you slowly deflect the arm 1/2" to one side and then release it, it should just go through zero by 1/16" or less and then fall back to zero. There are several problems with oil damping. It is very temperature sensitive, relatively difficult to set up, it is messy due to oil creep and it collects bugs - giving 'bug-quakes'! It is also 'non linear' in that it selectively damps short period motion much more than long period motion. The professionals stopped using it over 50 years ago.... I use a quad NdFeB bar magnet damping set-up. Two 1/4" thick mild steel plates 3.5" long by 2" wide are held apart by four 1/4" mild steel bolts and additional nuts at each corner. A NS pair of rectangular NdFeB magnets, 1" x 1/2" x 1/4" are placed on the centre of the face of one plate with the long axis parallel to the 2". A pair of SN magnets are placed on the opposing face of the other plate and the separation is adjusted to about 1/8" to 3/16". The central field gradient is simply huge. A 1/16" or 1/8" thick plate of soft Al or Cu about 2" wide and 3" long is mounted on the arm. It is important to make the damping plate wider than the 1" of the magnets to avoid field edge effects. The main damping is over the central 1" NS magnet joint. If you mount a L shaped Cu blade horizontally, you can just slide the magnet array further over it to increase the damping. You also reduce the damping by increasing the central magnetic gap. The stray field is low with this design. I put gaffer tape on the magnet faces and then peel it off before I assemble the two plates, to remove any magnetic debris / whiskers. You always get some and it is very difficult to see... > The bolt and 25mm wire > https://home.comcast.net/~bryangoss/boltwire.jpg > > The 5lb weight and coil > https://home.comcast.net/~bryangoss/coil.jpg If you mount the sensor magnet on the arm, it will respond to changing magnetic fields, the earth's field, power line surges, fridge motors, even to passing cars and lorries. If you mount the coil on the arm, it will be ~free of these interfering signals. You may detect movements of a few millionth's of an inch! The effective length of the arm is a bit shorter than the distance between the centre of the mass and the knife edge. You want this to be ~30 to 40" to give a long period. You might mount the mass quite a bit further along the arm? It is usual to attach the top suspension wire to a ~3" high vertical extension plate above the screw arm. This gives a small vertical pendulum effect and prevents the arm from rotating when it senses movement. This is necessary if you use a ball or wire suspension. > The overall I put the Seismograph in a clear box to prevent draft bit I > need to seal off the bottom this picture shows entire system and my messy > shop!!!!! > > https://home.comcast.net/~bryangoss/overall.jpg This looks OK, but you probably need to seal the edges of the case. You can buy 3" wide clear sticky tape for sealing greenhouse windows. This will take sunlight and it does not loose adhesion with time. Don't use cellotape, or ordinary pvc tape - they won't last long and you only want to do the job once! I would use two longitudinal L angles to support the whole base suspension, the sensor and the damping array plates. I use a single bolt at the centre of the mass end of the rig to alter the tilt angle. This makes adjustments a whole lot easier. You can set up each section / clearance in turn and the adjustments don't interact much. > https://home.comcast.net/~bryangoss/setup.jpg > I would mount the computer and monitor further away from the seismometer. You will certainly see a signal when you turn the monitor on, due to the large magnetic pulse used to demagnetise the screen. > Chris I am not sure how to do the FFT. I hope the screenshot of winsdr will > help, Thanks for the help If you all see something to improve I will try to > do it. > Thanks Very Much Bryan S Goss Corinth MS If you are using WinQuake, there is a tab labelled FFT on the top tool bar. You place the cursor where you want to start on the trace and click on. There should be a help file if you look for it. Hope that this is of some help! Are there two Corinths in MS? Regards, Chris Chapman In a message dated 03/04/2005, 1gos= s@........... writes:

This is a screenshot of WinSDR=20= It shows the 6 sec microseisms I think?
https://home.comc= ast.net/~bryangoss/winsdr.jpg


Hi Bryan,

       The time scale given is four minutes. W= ith a microseism period of ~6 sec, you should be looking at ~40 cycles total= .. This could fit the faster vibrations or it could all be mostly noise. Ther= e is certainly a lot of longer period stuff in with it.

This is the boom pivot point a=20= pipe union and razor blade
https://home.c= omcast.net/~bryangoss/pipeunion.jpg  is the ball bearing better tha= n the razer blade?


       Razor blades do not tend to last very=20= long. The idea seems to have arisen from the old system of knife edge bearin= gs for lab balances. These used 60 deg triangular agate bars resting on a fl= at agate plate. This only allowed about 200 gm load and the edge of the tria= ngle had a tiny radius lapped onto it. A razor blade is about 15 deg and ver= y sharp, so the edge load is huge and you are asking it to take > 2 kgm.=20= Umm. Stainless ball bearings last for ~ever. You should be able to get >2= 0 sec response without any problems

       You can buy stainless steel ball bearin= gs ~3/16", which do not corrode. For a flat, you can use a tungsten carbide=20= tool insert bit for a lathe. You can get flat triangular bits=20= with about 0.3" sides, quite cheaply. If you epoxy the bearing into a V hole= made with centre drill on the vertical support, turn the end of the boom ro= d flat and epoxy the tool bit onto this end, it should work very well. If yo= u mount the ball in the end of the swing arm, you will have to do a major le= velling operation every time you dismount the arm.....

This is the damping
https://home.com= cast.net/~bryangoss/damping.jpg


       You shouldn't need oil AND magnetic damping! The magnet set-up you have should give both verti= cal and horizontal damping! I suggest that you remove the oil and th= en reduce the magnet separation till you get just sub-critical damping? If y= ou can't get enough damping, use a 1/8" thick Cu plate. If you slowly deflec= t the arm 1/2" to one side and then release it, it should just go through ze= ro by 1/16" or less and then fall back to zero.
       There are several problems with oil dam= ping. It is very temperature sensitive, relatively difficult to set up, it i= s messy due to oil creep and it collects bugs - giving 'bug-quakes'! It is a= lso 'non linear' in that it selectively damps short period motion much more=20= than long period motion. The professionals stopped using it over 50 years ag= o....
       I use a quad NdFeB bar magnet damping s= et-up. Two 1/4" thick mild steel plates 3.5" long by 2" wide are held apart=20= by four 1/4" mild steel bolts and additional nuts at each corner. A NS pair=20= of rectangular NdFeB magnets, 1" x 1/2" x 1/4" are placed on the centre of t= he face of one plate with the long axis parallel to the 2". A pair of SN mag= nets are placed on the opposing face of the other plate and the separation i= s adjusted to about 1/8" to 3/16". The central field gradient is simply huge= .. A 1/16" or 1/8" thick plate of soft Al or Cu about 2" wide and 3" long is=20= mounted on the arm. It is important to make the damping plate wider than the= 1" of the magnets to avoid field edge effects. The main damping is over the= central 1" NS magnet joint. If you mount a L shaped Cu blade horizontally,=20= you can just slide the magnet array further over it to increase the damping.= You also reduce the damping by increasing the central magnetic gap. The str= ay field is low with this design. I put gaffer tape on the magnet faces and=20= then peel it off before I assemble the two plates, to remove any magnetic de= bris / whiskers. You always get some and it is very difficult to see...

The bolt and 25mm wire
https://home.comcast.net/~bryangoss/boltwire.jpg

The 5lb weight and coil
https://home.comcas= t.net/~bryangoss/coil.jpg


       If you mount the sensor magnet on the=20= arm, it will respond to changing magnetic fields, the earth's field, power l= ine surges, fridge motors, even to passing cars and lorries. If you mount th= e coil on the arm, it will be ~free of these interfering signals. You may de= tect movements of a few millionth's of an inch!

       The effective length of the arm is a bi= t shorter than the distance between the centre of the mass and the knife edg= e. You want this to be ~30 to 40" to give a long period. You might mount the= mass quite a bit further along the arm?

       It is usual to attach the top suspensio= n wire to a ~3" high vertical extension plate above the screw arm. This give= s a small vertical pendulum effect and prevents the arm from rotating when i= t senses movement. This is necessary if you use a ball or wire suspension.

The overall I put the Seismogr= aph in a clear box to prevent draft bit I need to seal off the bottom this p= icture shows entire system and my messy shop!!!!!

  https://h= ome.comcast.net/~bryangoss/overall.jpg


       This looks OK, but you probably need t= o seal the edges of the case. You can buy 3" wide clear sticky tape for seal= ing greenhouse windows. This will take sunlight and it does not loose adhesi= on with time. Don't use cellotape, or ordinary pvc tape - they won't last lo= ng and you only want to do the job once!

    I would use two longitudinal L angles to support the whol= e base suspension, the sensor and the damping array plates. I use a single b= olt at the centre of the mass end of the rig to alter the tilt angle. Thi= s makes adjustments a whole lot easier. You can set up each section / cl= earance in turn and the adjustments don't interact much.

  https://home.comcast.net/~bryangoss/setup.= jpg

   I would mount the computer and monitor further away from the s= eismometer. You will certainly see a signal when you turn the monitor on, du= e to the large magnetic pulse used to demagnetise the screen.

Chris I am not sure how to do t= he FFT. I hope the screenshot of winsdr will help, Thanks for the help If yo= u all see something to improve I will try to do it.
Thanks Very Much Bryan S Goss Corinth MS


       If you are using WinQuake, there is a t= ab labelled FFT on the top tool bar. You place the cursor where you want to=20= start on the trace and click on. There should be a help file if you look for= it.

       Hope that this is of some help! Are the= re two Corinths in MS?

       Regards,

       Chris Chapman
Subject: Re: noise From: BOB BARNS royb1@........... Date: Mon, 04 Apr 2005 09:48:02 -0400 You can perhaps eliminate convection in your box by attaching a heater to the underside of the lid. This should stagnate the air since the air is hotter at the top. I use an ordinary resistor supplied by a fairly large wall-wart. The resistor dissapates about 10W. A small lamp would also work. My box is 2" thick styrafoam which has excellant insulating properties. If your box is less insulating, it may take more heater power. I probed the inside of my box with a thermistor and found 2-3 deg. F difference with the top being hotter. Bob Barns 1goss@........... wrote: > I am having problems with noise during the night. Oddly it starts about 9:00pm and ends about 11:00 am. > > 9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg > > 11:00am WinSDR screenshot https://home.comcast.net/~bryangoss/noise11am.jpg > > I think these pictures will explain much more than I can. > > I thought it could be because the shop has a concrete floor and the air in the shop heats up to aournd 70F during the day and cools to around 36F at night. I believe the slower cooling of the floor during the night could be causing convection in the box. I tried to seal the box off and covered it with a blanket but that did not work. Could it be caused by the temperature change in the mineral oil and the vertical dampener? > > I ran FFT but to be honest, I'm not sure how to read it. > > Thank you for any help you can offer. > > Bryan S. Goss > > > > > > __________ NOD32 1.1044 (20050402) Information __________ > > This message was checked by NOD32 antivirus system. > http://www.nod32.com > > > > ------------------------------------------------------------------------ > > Subject: > Re: Got it going I think > From: > ChrisAtUpw@....... > Date: > Sun, 3 Apr 2005 00:37:47 +0000 > To: > psn-l@.............. > > > In a message dated 02/04/2005, 1goss@........... writes: > >> I got my Lehman Seismometer up and running I think I may have my gain >> set a bit high, But I think it is ok. > > > > HI Bryan, > > It looks like you have a fairly high gain on the amplifier. I > suggest that you examine sections of the trace, do a FFT on it and check > to see if the ~six second ocean background is dominant or if there is a > lot of other noise. Try wedging the mass so that it can't move to check > on instrument noise? I can't tell much from the drumplot, since I don't > know how it was scaled. It doesn't show any waveforms or any peak > counts. You need to click on X-Scale at the top of the display and then > select 'counts'. > The display shows small deflections during the night, but much > larger ones during the 'working day'. Do you have a lot of traffic / > industrial noise? > > What sort of suspensions / bearings are you using? A 12 sec plot > doesn't give you much 'headroom' over the 6 sec microseisms. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: noise From: Jack Ivey ivey@.......... Date: Mon, 4 Apr 2005 12:43:49 -0400 Bryan, It might also help to add insulation to the bottom of the box. Of course you have to have holes to let the seismo feet touch the floor underneath, and it would have to be thin enough that there is no contact between the seismo and the insulation. Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of BOB BARNS Sent: Monday, April 04, 2005 9:48 AM To: psn-l@.............. Subject: Re: noise You can perhaps eliminate convection in your box by attaching a heater to the underside of the lid. This should stagnate the air since the air is hotter at the top. I use an ordinary resistor supplied by a fairly large wall-wart. The resistor dissapates about 10W. A small lamp would also work. My box is 2" thick styrafoam which has excellant insulating properties. If your box is less insulating, it may take more heater power. I probed the inside of my box with a thermistor and found 2-3 deg. F difference with the top being hotter. Bob Barns 1goss@........... wrote: > I am having problems with noise during the night. Oddly it starts about 9:00pm and ends about 11:00 am. > > 9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg > > 11:00am WinSDR screenshot https://home.comcast.net/~bryangoss/noise11am.jpg > > I think these pictures will explain much more than I can. > > I thought it could be because the shop has a concrete floor and the air in the shop heats up to aournd 70F during the day and cools to around 36F at night. I believe the slower cooling of the floor during the night could be causing convection in the box. I tried to seal the box off and covered it with a blanket but that did not work. Could it be caused by the temperature change in the mineral oil and the vertical dampener? > > I ran FFT but to be honest, I'm not sure how to read it. > > Thank you for any help you can offer. > > Bryan S. Goss > > > > > > __________ NOD32 1.1044 (20050402) Information __________ > > This message was checked by NOD32 antivirus system. > http://www.nod32.com > > > > ------------------------------------------------------------------------ > > Subject: > Re: Got it going I think > From: > ChrisAtUpw@....... > Date: > Sun, 3 Apr 2005 00:37:47 +0000 > To: > psn-l@.............. > > > In a message dated 02/04/2005, 1goss@........... writes: > >> I got my Lehman Seismometer up and running I think I may have my gain >> set a bit high, But I think it is ok. > > > > HI Bryan, > > It looks like you have a fairly high gain on the amplifier. I > suggest that you examine sections of the trace, do a FFT on it and check > to see if the ~six second ocean background is dominant or if there is a > lot of other noise. Try wedging the mass so that it can't move to check > on instrument noise? I can't tell much from the drumplot, since I don't > know how it was scaled. It doesn't show any waveforms or any peak > counts. You need to click on X-Scale at the top of the display and then > select 'counts'. > The display shows small deflections during the night, but much > larger ones during the 'working day'. Do you have a lot of traffic / > industrial noise? > > What sort of suspensions / bearings are you using? A 12 sec plot > doesn't give you much 'headroom' over the 6 sec microseisms. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: WWSN Drum Recorder From: Richard Webb dwebb002@............. Date: Mon, 04 Apr 2005 16:20:46 -0400 Hi, I have a 3 sheet drum recorder from the old WWSN system. It was set up to record photographically. Once upon a time I had plans to convert it to a standard pen recorder by ran into $$ problem. I also still have some of the components for the photo system of the recorder. I do not have the galvanometer component. I am looking for a good home for it if anyone is interested in an excellent drum recorder in excellent condition. Unfortunately, it weighs 50-100 lbs so shipping is not a good idea. However, I will be driving to the SSA meeting in a few weeks and would be willing to bring it with me and give it (no charge) to anyone who wants it. I also have a few pen parts and a box of paper. I just want to find it a good home and not throw it in the trash. Let me know if you are interested. Thanks, Dick Webb Raleigh, NC __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: improvements From: ChrisAtUpw@....... Date: Mon, 4 Apr 2005 18:44:59 EDT In a message dated 04/04/2005, 1goss@........... writes: > I would like very much to see detailed pictures of your setup. It would > help me to better understand the improvements you suggested. HI Bryan, I am away from home at the moment, but I will do a sketch. I use a very different design. My concern when looking at your setup is to try to think what you can do to get your system to work well. > I have 2 questions: > 1. If you put the coil on the boom how do you keep the wire from interfering > with the swing or period. You run ordinary two core wire along the arm, taping it on every 6". Over the bearing you mount two vertical 'hairpin' shapes of the thinnest magnet wire that you can easily get, maybe 3" long. These are soldered between the cable on the arm and the cable from the baseplate to the amplifier. The amount of spring in them is tiny and should be ~constant. You can also wind ~10 turn coils onto a 3/16" rod and loop the free coil over the bearing. RS sell 30G magnet wire and 30 gauge wrap wire. This is 10 thou dia, which is still a bit thick. I can get 5 thou wire wrap easily from other sources, but I use a reel of 2 thou which I bought many years ago. If you can get wire with polyurethane insulation, you can solder it directly using a hot iron. The insulation just melts. > 2 I used 3/8 all thread, as you could see. I was afraid it would bend under > the weight as I noted the 4ft length of the rod was flexible when I bought > it. > What size rod did you use? What size should I use? oops went over 2 > questions. You should be able to get about 30" OK? What is the ~distance between the centre of the weight and the knife edge at the moment? I don't use 'all-thread' at all. I use 1/2" nominal stainless steel water pipe (~19/32") and brass compression water fittings, stop ends, Ts and Xs. I drill out the central hole of the T or X to give a clearance for the pipe. > 3 My nightmare the only place I can put the seismograph is in my shop it is > very UN-level. I could not believe how much. It sets on sand near a ditch > when I level the boom their is over an inch difference from one end to the > other, this makes a hard job harder. > I had considered pouring a small amount of concrete to try and fix this. Ordinary concrete with gravel in it can be quite 'noisy' as the temperature changes, although 3' x 2' paving slabs have been used. The recommended mix is 50:50 cement and sand by volume. You mix it fairly wet and vibrate it if possible, to remove air bubbles. You cover it with polythene sheet for over a week to keep it wet and allow it to 'cure'. It may take a month to cure fully. What is your floor made of? It looks like wood block.... What is the construction of your 'shop'? What is the ground material if you dig a hole outside? Do you get to solid rock at any practicable depth? > also tonight late I had very little noise so it seems as their was no big > temperature contrast, this may well be the bigger problem. I ran FFT on the > low noise output of the seismograph and I clearly saw a spike the 6 sec > microseisms. You need to be able to see the 6 sec microseism peak quite clearly. This is a good thing I right? but I am still going to improve it. I can't see a 6 sec peak (0.17 Hz) on the FFT you posted. You read the frequency / period figures at the top of the screen for the ^ cursor position. It is the larger amplitude low frequency stuff between 0.1 and 0.01 Hz which concerns me. It is maybe 100x what it should be. I suspect that the noise is at least partially due to air currents, from your description. Could it be partially due to your whole shop heating and cooling? Does it make any creaking noises? How does wind effect the signal? Regards, Chris Chapman In a message dated 04/04/2005, 1gos= s@........... writes:

I would like very much to see d= etailed pictures of your setup. It would help me to better understand the im= provements you suggested.


HI Bryan,

       I am away from home at the moment, but=20= I will do a sketch. I use a very different design. My concern when looking a= t your setup is to try to think what you can do to get your system to= work well.


I have 2 questions:
1. If you put the coil on the boom how do you keep the wire from interfering= with the swing or period.


       You run ordinary two core wire along t= he arm, taping it on every 6". Over the bearing you mount two vertical 'hair= pin' shapes of the thinnest magnet wire that you can easily get, maybe 3" lo= ng. These are soldered between the cable on the arm and the cable from the b= aseplate to the amplifier. The amount of spring in them is tiny and should b= e ~constant. You can also wind ~10 turn coils onto a 3/16" rod and loop the=20= free coil over the bearing.
       RS sell 30G magnet wire and 30 gauge wr= ap wire. This is 10 thou dia, which is still a bit thick. I can get 5 thou w= ire wrap easily from other sources, but I use a reel of 2 thou which I bough= t many years ago. If you can get wire with polyurethane insulation, you can=20= solder it directly using a hot iron. The insulation just melts.

2 I used 3/8 all thread, as you= could see. I was afraid it would bend under the weight as I noted the 4ft l= ength of the rod was flexible when I bought it.
What size rod did you use? What size should I use? oops went over 2 question= s.


       You should be able to get about 30" OK= ? What is the ~distance between the centre of the weight and the knife edge=20= at the moment?

      I don't use 'all-thread' at all. I use 1/2" n= ominal stainless steel water pipe (~19/32") and brass compression water fitt= ings, stop ends, Ts and Xs. I drill out the central hole of the T or X to gi= ve a clearance for the pipe.


3 My nightmare the only place I= can put the seismograph is in my shop it is very UN-level. I could not beli= eve how much. It sets on sand near a ditch  when I level the boom their= is over an inch difference from one end to the other, this makes a hard job= harder.
I had considered pouring a small amount of concrete to try and fix this.


       Ordinary concrete with gravel in it ca= n be quite 'noisy' as the temperature changes, although 3' x 2' paving slabs= have been used. The recommended mix is 50:50 cement and sand by volume. You= mix it fairly wet and vibrate it if possible, to remove air bubbles. You co= ver it with polythene sheet for over a week to keep it wet and allow it to '= cure'. It may take a month to cure fully.

       What is your floor made of? It looks li= ke wood block....

       What is the construction of your 'shop'= ?

       What is the ground material if you dig=20= a hole outside? Do you get to solid rock at any practicable depth?

also tonight late I had very li= ttle noise so it seems as their was no big temperature contrast, this may we= ll be the bigger problem. I ran FFT on the low noise output of the seismogra= ph and I clearly saw a spike the 6 sec microseisms.


       You need to be able to see the 6 sec m= icroseism peak quite clearly.

This is a good thing I right? but I am still going to improve it.


       I can't see a 6 sec peak (0.17 Hz) on t= he FFT you posted. You read the frequency / period figures at the top of the= screen for the ^ cursor position. It is the larger amplitude low frequency=20= stuff between 0.1 and 0.01 Hz which concerns me. It is maybe 100x what it sh= ould be. I suspect that the noise is at least partially due to air currents,= from your description.
       Could it be partially due to your whole= shop heating and cooling? Does it make any creaking noises? How does wind e= ffect the signal?

       Regards,

       Chris Chapman
Subject: Re: improvements From: 1goss@........... Date: Tue, 05 Apr 2005 09:33:31 +0000 Chris, "What is the ~distance between the center of the weight and the knife edge at the moment?" About 15 inches. "What is your floor made of?" My shop floor is cement 20x40. "What is the construction of your 'shop'?" Wood 2 level barn style. "What is the ground material if you dig a hole outside?" Red clay "Do you get to solid rock at any practicable depth?" No solid rock here, to 70 ft +. "How does wind effect the signal?" Wind to 5 MPH does not affect the output. I am not sure about more than that. "Does it make any creaking noises?" Yes but mostly with sharp temperature changes. Could you send me a psn file with nominal noise and 6 sec microseisms, or if someone would like to post a link to a file. I would like to see about a Minute of time from a good signal. The noise has greatly decreased. Here is a link to the latest FFT with the lower noise level. I am not sure bout the 6 sec microseisms. This is 1 Minute of time. WinQuake 1 Min https://home.comcast.net/~bryangoss/WinQuake.jpg FFT 1 Min https://home.comcast.net/~bryangoss/FFT.jpg Thanks for all the help Bryan S Goss In a message dated 04/04/2005, 1goss@........... writes: > I would like very much to see detailed pictures of your setup. It would > help me to better understand the improvements you suggested. HI Bryan, I am away from home at the moment, but I will do a sketch. I use a very different design. My concern when looking at your setup is to try to think what you can do to get your system to work well. > I have 2 questions: > 1. If you put the coil on the boom how do you keep the wire from interfering > with the swing or period. You run ordinary two core wire along the arm, taping it on every 6". Over the bearing you mount two vertical 'hairpin' shapes of the thinnest magnet wire that you can easily get, maybe 3" long. These are soldered between the cable on the arm and the cable from the baseplate to the amplifier. The amount of spring in them is tiny and should be ~constant. You can also wind ~10 turn coils onto a 3/16" rod and loop the free coil over the bearing. RS sell 30G magnet wire and 30 gauge wrap wire. This is 10 thou dia, which is still a bit thick. I can get 5 thou wire wrap easily from other sources, but I use a reel of 2 thou which I bought many years ago. If you can get wire with polyurethane insulation, you can solder it directly using a hot iron. The insulation just melts. > 2 I used 3/8 all thread, as you could see. I was afraid it would bend under > the weight as I noted the 4ft length of the rod was flexible when I bought > it. > What size rod did you use? What size should I use? oops went over 2 > questions. You should be able to get about 30" OK? What is the ~distance between the centre of the weight and the knife edge at the moment? I don't use 'all-thread' at all. I use 1/2" nominal stainless steel water pipe (~19/32") and brass compression water fittings, stop ends, Ts and Xs. I drill out the central hole of the T or X to give a clearance for the pipe. > 3 My nightmare the only place I can put the seismograph is in my shop it is > very UN-level. I could not believe how much. It sets on sand near a ditch > when I level the boom their is over an inch difference from one end to the > other, this makes a hard job harder. > I had considered pouring a small amount of concrete to try and fix this. Ordinary concrete with gravel in it can be quite 'noisy' as the temperature changes, although 3' x 2' paving slabs have been used. The recommended mix is 50:50 cement and sand by volume. You mix it fairly wet and vibrate it if possible, to remove air bubbles. You cover it with polythene sheet for over a week to keep it wet and allow it to 'cure'. It may take a month to cure fully. What is your floor made of? It looks like wood block.... What is the construction of your 'shop'? What is the ground material if you dig a hole outside? Do you get to solid rock at any practicable depth? > also tonight late I had very little noise so it seems as their was no big > temperature contrast, this may well be the bigger problem. I ran FFT on the > low noise output of the seismograph and I clearly saw a spike the 6 sec > microseisms. You need to be able to see the 6 sec microseism peak quite clearly. This is a good thing I right? but I am still going to improve it. I can't see a 6 sec peak (0.17 Hz) on the FFT you posted. You read the frequency / period figures at the top of the screen for the ^ cursor position. It is the larger amplitude low frequency stuff between 0.1 and 0.01 Hz which concerns me. It is maybe 100x what it should be. I suspect that the noise is at least partially due to air currents, from your description. Could it be partially due to your whole shop heating and cooling? Does it make any creaking noises? How does wind effect the signal? Regards, Chris Chapman In a message dated 04/04/2005, 1gos= s@........... writes:

I would like very much to see d= etailed pictures of your setup. It would help me to better understand the im= provements you suggested.


HI Bryan,

       I am away from home at the moment, but=20= I will do a sketch. I use a very different design. My concern when looking a= t your setup is to try to think what you can do to get your system to= work well.


I have 2 questions:
1. If you put the coil on the boom how do you keep the wire from interfering= with the swing or period.


       You run ordinary two core wire along t= he arm, taping it on every 6". Over the bearing you mount two vertical 'hair= pin' shapes of the thinnest magnet wire that you can easily get, maybe 3" lo= ng. These are soldered between the cable on the arm and the cable from the b= aseplate to the amplifier. The amount of spring in them is tiny and should b= e ~constant. You can also wind ~10 turn coils onto a 3/16" rod and loop the=20= free coil over the bearing.
       RS sell 30G magnet wire and 30 gauge wr= ap wire. This is 10 thou dia, which is still a bit thick. I can get 5 thou w= ire wrap easily from other sources, but I use a reel of 2 thou which I bough= t many years ago. If you can get wire with polyurethane insulation, you can=20= solder it directly using a hot iron. The insulation just melts.

2 I used 3/8 all thread, as you= could see. I was afraid it would bend under the weight as I noted the 4ft l= ength of the rod was flexible when I bought it.
What size rod did you use? What size should I use? oops went over 2 question= s.


       You should be able to get about 30" OK= ? What is the ~distance between the centre of the weight and the knife edge=20= at the moment?

      I don't use 'all-thread' at all. I use 1/2" n= ominal stainless steel water pipe (~19/32") and brass compression water fitt= ings, stop ends, Ts and Xs. I drill out the central hole of the T or X to gi= ve a clearance for the pipe.


3 My nightmare the only place I= can put the seismograph is in my shop it is very UN-level. I could not beli= eve how much. It sets on sand near a ditch  when I level the boom their= is over an inch difference from one end to the other, this makes a hard job= harder.
I had considered pouring a small amount of concrete to try and fix this.


       Ordinary concrete with gravel in it ca= n be quite 'noisy' as the temperature changes, although 3' x 2' paving slabs= have been used. The recommended mix is 50:50 cement and sand by volume. You= mix it fairly wet and vibrate it if possible, to remove air bubbles. You co= ver it with polythene sheet for over a week to keep it wet and allow it to '= cure'. It may take a month to cure fully.

       What is your floor made of? It looks li= ke wood block....

       What is the construction of your 'shop'= ?

       What is the ground material if you dig=20= a hole outside? Do you get to solid rock at any practicable depth?

also tonight late I had very li= ttle noise so it seems as their was no big temperature contrast, this may we= ll be the bigger problem. I ran FFT on the low noise output of the seismogra= ph and I clearly saw a spike the 6 sec microseisms.


       You need to be able to see the 6 sec m= icroseism peak quite clearly.

This is a good thing I right? but I am still going to improve it.


       I can't see a 6 sec peak (0.17 Hz) on t= he FFT you posted. You read the frequency / period figures at the top of the= screen for the ^ cursor position. It is the larger amplitude low frequency=20= stuff between 0.1 and 0.01 Hz which concerns me. It is maybe 100x what it sh= ould be. I suspect that the noise is at least partially due to air currents,= from your description.
       Could it be partially due to your whole= shop heating and cooling? Does it make any creaking noises? How does wind e= ffect the signal?

       Regards,

       Chris Chapman
Subject: Question About Analog Seismo Telemetered On 163.797 in So.Cal From: Douglas Gavilanes gavilan1@............. Date: Wed, 06 Apr 2005 15:35:00 -0700 Greetings from under my rock. I have received a few questions recently from fellow amateur radio folks about the *general* location of the seismo that is currently telemetered via VHF (163.797MHz) into the LA basin (for the Caltech Seismo Lab). I'm not seeking an exact location. Most believe it to be located at Crystal Lake, L.A. Co., but I believe having heard that it was on Catalina Island. The Crystal Lake seismo (which most of us affiliated with PSN Pasadena listened to) was just off of 162.810, but it went fiber or satellite ages ago. Many of us built discriminators back then for its 680Hz tone, with data outputs, alarms, etc. In any case, a few ham folks would like to know which way to point a dedicated beam antenna for best signal reception. Since it is so weak, one can't be sure if their antenna is aimed at the transmitter, or at a reflection off of a mountain or building. Any direction here (pun intended) is appreciated. Off list is OK, if you're concerned. Regards, Doug Gavilanes Garden Grove, CA. n6xqy@........ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Question About Analog Seismo Telemetered On 163.797 in So.Cal From: Larry Cochrane lcochrane@.............. Date: Thu, 07 Apr 2005 19:50:21 -0700 Doug, I have located remote sensor locations by recording the data and using known local event epicenters to triangulate the locate of the sensor. You can use my WinQuake program to do this. Another way is to use the P arrival time and look at an event list that has P arrive times for each station. If you have accurate timing you should be able to find the station. The local USGS or maybe Cal Tech should publish a list with this information in it. Once you have the station ID you should be able to look up the sensor location on the USGS site. Good luck. Larry Cochrane Redwood City, PSN Douglas Gavilanes wrote: > Greetings from under my rock. I have received a few questions recently > from fellow amateur radio folks about the *general* location of the > seismo that is currently telemetered via VHF (163.797MHz) into the LA > basin (for the Caltech Seismo Lab). I'm not seeking an exact location. > Most believe it to be located at Crystal Lake, L.A. Co., but I believe > having heard that it was on Catalina Island. The Crystal Lake seismo > (which most of us affiliated with PSN Pasadena listened to) was just off > of 162.810, but it went fiber or satellite ages ago. Many of us built > discriminators back then for its 680Hz tone, with data outputs, alarms, > etc. In any case, a few ham folks would like to know which way to point > a dedicated beam antenna for best signal reception. Since it is so > weak, one can't be sure if their antenna is aimed at the transmitter, or > at a reflection off of a mountain or building. Any direction here (pun > intended) is appreciated. Off list is OK, if you're concerned. > > Regards, > > Doug Gavilanes > Garden Grove, CA. > n6xqy@........ > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: first event From: 1goss@........... Date: Fri, 08 Apr 2005 07:24:08 +0000 I sent this to Center for Earthquake Research and Information (CERI) And to my surprise got this response this was interesting + it is the first event I recorded on my Lehman seismometer. My letter to CERI : > >I see an event that looks like a micro quake > >on the Recent Helicorder Display > >"http://folkworm.ceri.memphis.edu/heli_nm/" > > PWLA EHZ NM : Pickwick Lake, AL > > I saw it on my homebuilt Lehman seismometer > >In corinth MS. as well this is why I ask. > > > >Event UTC 4/5/05 21:07:30 to 21:08:51 > >This is my data > >https://home.comcast.net/~bryangoss/micro.jpg > > > >It is not on the Recent Earthquakes in Central US that I can find?? THE REPLY BY CERI: On Thu, 7 Apr 2005, Gary Patterson wrote: > Hello Bryan, > > Thanks for your input. Seems we may have a processing glitch for > that event (maybe from the time change...maybe from something else). > We listed an event at > 2.9 2005/04/05 15:37:43 36.150N 83.690W 10.1 (20:37:43 (UTC) .... > looks like it should have been listed at the time you specified > (about 21:07 for the first arrival at pickwick). It is very clear on > the pickwick (PWLA) station. > > I know that these types of glitches dont happen often and I > appreciate you bringing it to our attention. Staff are looking for > the problem now. > > Additionally, your Lehman seismometer seems to be working well. > Hopefully you will continue to monitor earthquakes in the > area.....it's great to have someone else out there. > > Regards, > > Good luck This message was sent to you by 69.244.24.49 > >on Wed Apr 6 07:15:29 2005 (GMT). > Mitch Center for Earthquake Research and Information (CERI) University of Memphis Ph: 901-678-4940 Memphis, TN 38152 Fax: 901-678-4734 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Telemetry From: 1goss@........... Date: Sat, 09 Apr 2005 10:10:05 +0000 I have a few questons about Telemetry. I am about 30 miles from a station at PWLA EHZ NM : Pickwick Lake, AL and wanted to know If I could pick up the Telemetry from that station.If it has Telemetry and what frequency it would be on. This statement was on CERI pape. "The CERI seismic networks are subdivided into autonomous, remote processing nodes. Each node acts as a central site for FM telemetry reception and processing, digitizing, and earthworm processing. Digital connections to Memphis are established by various means. Some stations are additionally telemetered back to Memphis." I would like to try Larry Cochrane,s Telemetry Demodulator Board. Thanks Bryan Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Telemetry From: Richard Webb dwebb002@............. Date: Sat, 09 Apr 2005 08:05:42 -0400 You might give the people at CERI a call or email. They are an extremely helpful bunch. Dick 1goss@........... wrote: >I have a few questons about Telemetry. I am about 30 miles from a station at PWLA EHZ NM : Pickwick Lake, AL and wanted to know If I could pick up the Telemetry from that station.If it has Telemetry and what frequency it would be on. This statement was on CERI pape. > "The CERI seismic networks are subdivided into autonomous, remote processing nodes. Each node acts as a central site for FM telemetry reception and processing, digitizing, and earthworm processing. Digital connections to Memphis are established by various means. Some stations are additionally telemetered back to Memphis." > >I would like to try Larry Cochrane,s Telemetry Demodulator Board. >Thanks Bryan Goss >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: first event From: "Thomas Dick" dickthomas01@............. Date: Sat, 9 Apr 2005 07:47:26 -0500 I, too, copied that event here in Evansville,IN ... arrived at 21:09 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Network time standard From: "Steve Hammond" shammon1@............. Date: Sat, 9 Apr 2005 09:00:18 -0700 PSN members, I'm writing to report on a software network time client server software program that is compatible with WinSDR. I'm using Larry's serial connected A/D hardware with a Motorola GPS for data collection and realized that I could have my own home network time standard if I could find a compatible software package. After looking and trying three different products, I selected Net Time version 2.1 because it works seamlessly with WinSDR. You can obtain a trial version of the software from Http://www.han-soft.com I think you will find it to be compatible with all the MS operating systems. A few observation notes: While you can install the same copy of the trial software on two different systems, you need to purchase a server "Full License" for $25.00 for the time server (the machine running WinSDR) and a "Client License" for $12.99 for each client using the new network time service. The software includes a list of known Internet time servers and also allows you to assign the local IP address of your in-house network time server. The software is configurable with and support several different protocols. I'm using SNTP on port 123 which does not conflict with any other ports currently in use by the system. I had some issues with the initial install because I didn't understand the licensing methodology but was able to sort it out with the help of the Han-soft support rep who provide prompt and high-quality service. If you don't have a GPS, as I said, the software comes with an extensive list of network time servers that can be accessed via the Internet to obtain accurate time. Overall, the experience with this software package has been very positive and after 30-days of testing I'm now recommending it to other members of the Public Seismic Network. Regards, Steve Hammond, Aptos CA Public Seismic Network San Jose California Http://www.publicseismicnetowrk.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Network time standard From: ian ian@........... Date: Sat, 09 Apr 2005 17:18:11 +0100 an interesting experiment would be to see what the magnitude of the time drift is between a computer using an internet network time server (synchronised at regular intervals) and one using a gps time board. It would also be interesting to then calculate what the typical positional error would be (of an epicentre) for a pc using an internet network time server, using gps time as a base line. Ian Smith Steve Hammond wrote: >PSN members, >I'm writing to report on a software network time client server software >program that is compatible with WinSDR. I'm using Larry's serial connected >A/D hardware with a Motorola GPS for data collection and realized that I >could have my own home network time standard if I could find a compatible >software package. > >After looking and trying three different products, I selected Net Time >version 2.1 because it works seamlessly with WinSDR. You can obtain a trial >version of the software from Http://www.han-soft.com I think you will find >it to be compatible with all the MS operating systems. > >A few observation notes: While you can install the same copy of the trial >software on two different systems, you need to purchase a server "Full >License" for $25.00 for the time server (the machine running WinSDR) and a >"Client License" for $12.99 for each client using the new network time >service. The software includes a list of known Internet time servers and >also allows you to assign the local IP address of your in-house network time >server. The software is configurable with and support several different >protocols. I'm using SNTP on port 123 which does not conflict with any other >ports currently in use by the system. I had some issues with the initial >install because I didn't understand the licensing methodology but was able >to sort it out with the help of the Han-soft support rep who provide prompt >and high-quality service. > >If you don't have a GPS, as I said, the software comes with an extensive >list of network time servers that can be accessed via the Internet to obtain >accurate time. Overall, the experience with this software package has been >very positive and after 30-days of testing I'm now recommending it to other >members of the Public Seismic Network. > > >Regards, Steve Hammond, Aptos CA >Public Seismic Network San Jose California >Http://www.publicseismicnetowrk.com > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Network time standard From: ChrisAtUpw@....... Date: Sat, 9 Apr 2005 16:05:42 EDT In a message dated 09/04/2005, shammon1@............. writes: If you don't have a GPS, as I said, the software comes with an extensive list of network time servers that can be accessed via the Internet to obtain accurate time. Overall, the experience with this software package has been very positive and after 30-days of testing I'm now recommending it to other members of the Public Seismic Network. Hi Steve, Does it give any timing accuracies in milli seconds for the various time servers? One of the problems with time services is that while the signal may leave the server on time, it may be digitally delayed on it's way though the telecom system. Since there are many services now operating, the inaccuracy around some timing marks may be very significant. What timing errors have you measured, please? About the Public NTP Time Server Lists The lists are provided for information purposes only and represent the best information available at the current date. The operators of the servers listed do not commit to provide time service other than on a volunteer basis and with no guarantee of accuracy or availability. Further information of a technical nature can be obtained from the _www.ntp.org_ (http://www.ntp.org/) site, the _comp.protocols.time.ntp_ (news:comp.protocols.time.ntp) newsgroup, or the _NTP Support_ (http://ntp.isc.org/bin/view/Support/WebHome) Web. Regards, Chris Chapman
In a message dated 09/04/2005, shammon1@............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If you=20 don't have a GPS, as I said, the software comes with an extensive
list=20= of=20 network time servers that can be accessed via the Internet to=20 obtain
accurate time. Overall, the experience with this software packag= e=20 has been
very positive and after 30-days of testing I'm now recommendin= g it=20 to other
members of the Public Seismic Network.
=
Hi Steve,
 
    Does it give any timing accuracies in mill= i=20 seconds for the various time servers?
 
    One of the problems with time services is that=20 while the signal may leave the server on time, it may be digitally delayed o= n=20 it's way though the telecom system. Since there are many services now operat= ing,=20 the inaccuracy around some timing marks may be very significant.
 
    What timing errors have you measured, please?
 
About the Public NTP Time Server Lists

The lists are provided for information purposes only and represent the be= st=20 information available at the current date. The operators of the servers list= ed=20 do not commit to provide time service other than on a volunteer basis and wi= th=20 no guarantee of accuracy or availability. Further information of a technical= =20 nature can be obtained from the www.ntp.org site, the comp.protocols.time.ntp newsgroup, or the NTP Support Web.=20

    Regards,
 
    Chris Chapman
 
     
Subject: RE: Network time standard From: "Keith Payea" kpayea@........... Date: Sat, 9 Apr 2005 13:53:14 -0700 Not all NTP clients are created equal... There are actually two standards. True NTP uses four time stamps to attempt to correct for transmission delays, and also runs a fairly complex filter based on many samples to set the time in your computer. Simple NTP (SNTP) uses just one time stamp, and is usually run once a day or every few hours with no filtering. Try to find an NTP that is based on the University of Delaware version. Dr. Mills at UDel is considered the true guru of NTP and his team have put many years into squeezing the best performance out of it. My experience when working for TrueTime (Now a division of Symmetricom) was that you could achieve 10 milliseconds or so if the server was not too far away on the public internet. If you run a local time service on your own network, the timing is much better than that. It usually takes several messages to get there due to the filtering. Also, true NTP will perform much better if you give it more than one server to work with. The software makes some attempt to evaluate the stability of each source and choose the best. Obviously, NTP is not as good as GPS, but it is very comparable to WWV or WWVB or DCF77 radio performance. Cheers, Keith _____ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Saturday, April 09, 2005 1:06 PM To: psn-l@.............. Subject: Re: Network time standard In a message dated 09/04/2005, shammon1@............. writes: If you don't have a GPS, as I said, the software comes with an extensive list of network time servers that can be accessed via the Internet to obtain accurate time. Overall, the experience with this software package has been very positive and after 30-days of testing I'm now recommending it to other members of the Public Seismic Network. Hi Steve, Does it give any timing accuracies in milli seconds for the various time servers? One of the problems with time services is that while the signal may leave the server on time, it may be digitally delayed on it's way though the telecom system. Since there are many services now operating, the inaccuracy around some timing marks may be very significant. What timing errors have you measured, please? About the Public NTP Time Server Lists The lists are provided for information purposes only and represent the best information available at the current date. The operators of the servers listed do not commit to provide time service other than on a volunteer basis and with no guarantee of accuracy or availability. Further information of a technical nature can be obtained from the www.ntp.org site, the comp.protocols.time.ntp newsgroup, or the NTP Support Web. Regards, Chris Chapman
Not all NTP = clients are=20 created equal...  There are actually two standards.  True NTP = uses=20 four time stamps to attempt to correct for transmission delays, and also = runs a=20 fairly complex filter based on many samples to set the time in your=20 computer.  Simple NTP (SNTP) uses just one time stamp, and is = usually run=20 once a day or every few hours with no filtering.
 
Try to find = an NTP that=20 is based on the University of Delaware version.  Dr. Mills at UDel = is=20 considered the true guru of NTP and his team have put many years = into=20 squeezing the best performance out of it.
 
My = experience when=20 working for TrueTime (Now a division of Symmetricom) was that you could = achieve=20 10 milliseconds or so if the server was not too far away on the public=20 internet.  If you run a local time service on your own network, the = timing=20 is much better than that.  It usually takes several messages to get = there=20 due to the filtering.  Also, true NTP will perform much better if = you give=20 it more than one server to work with.  The software makes some = attempt to=20 evaluate the stability of each source and choose the best.
 
Obviously, NTP is=20 not as good as GPS, but it is very comparable to WWV or WWVB or DCF77 = radio=20 performance.
 
Cheers,
 
Keith
 
 


From: psn-l-request@................. [mailto:psn-l-request@............... On Behalf Of=20 ChrisAtUpw@.......
Sent: Saturday, April 09, 2005 1:06=20 PM
To: psn-l@..............
Subject: Re: Network = time=20 standard

In a message dated 09/04/2005, shammon1@............. writes:
If you don't have = a GPS, as I=20 said, the software comes with an extensive
list of network time = servers=20 that can be accessed via the Internet to obtain
accurate time. = Overall, the=20 experience with this software package has been
very positive and = after=20 30-days of testing I'm now recommending it to other
members of the = Public=20 Seismic Network.
Hi Steve,
 
    Does it give any timing accuracies in = milli=20 seconds for the various time servers?
 
    One of the problems with time services is = that=20 while the signal may leave the server on time, it may be digitally = delayed on=20 it's way though the telecom system. Since there are many services now = operating,=20 the inaccuracy around some timing marks may be very significant.
 
    What timing errors have you measured, = please?
 
About the Public NTP Time Server Lists

The lists are provided for information purposes only and represent = the best=20 information available at the current date. The operators of the servers = listed=20 do not commit to provide time service other than on a volunteer basis = and with=20 no guarantee of accuracy or availability. Further information of a = technical=20 nature can be obtained from the www.ntp.org site, the comp.protocols.time.ntp newsgroup, or the NTP Support = Web.=20

    Regards,
 
    Chris Chapman
 
     
Subject: RE: Network time standard From: John or Jan Lahr JohnJan@........ Date: Sat, 09 Apr 2005 17:51:19 -0600 At 02:53 PM 4/9/2005, Keith wrote: >Not all NTP clients are created equal... In your experience, which is the best, free time-sync software for a PC with an Internet connection but no local time server. Can you evaluate AboutTime: http://www.arachnoid.com/abouttime/ ? Thanks, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Network time standard From: "Steve Hammond" shammon1@............. Date: Sat, 9 Apr 2005 16:57:54 -0700 Hi, Remember, this is an inexpensive program. I cut and pasted the help documentation below the logs just below that. My home network is a 100 Mbs network with no traffic. I set the time out(ms) to 1ms and got a timeout error. I set it to 2ms and was able to perform the system synchronization. (See log entry for AT4) This implies that the two-way delay in my network is less than 2MS which is a reasonable assumption. I then pointed the software at the AOL time standard in San Jose CA and was not able to perform the system synchronization at 30 MS and received a timeout error and then was able to perform the system synchronization in 40 ms.(See log entry USA-2) I was also able to connect and set the time. I then configure and connect to an HP 58503A GPS network time standard which I also have running in my network using the GPSCon software utility. I configured GPSCon as a time standard and was able to perform the system synchronization (See log message HP) The one think I did notice was that I had to up the timeout count on both systems after I started to broadcast the time using the HP time standard and GPSCon software on my network. Because of that, I think there is some correlation to the decimal value in each of the log messages following the date time PM entry. I'll let you come to your own conclusions. I believe that to perform the system synchronization mean just that. There is one more issue which I think is also worth mentioning and it is the PC system clock is set by WinSDR on AT4.The GPSCon software is reading the time via a Com port connected to the HP58503A and acting as a network enabled time standard. I'm certain there will be some loss of time in the system activity on both AT1 the HP system and AT4 the system running WinSdr. Maybe Larry can comment. The Net Time service is dependent on the PC time on AT4 which is set by the GPS clock set system time function in WinSDR. On the HP system it is dependent on the system software application GPScon. Regards, Steve Hammond Aptos, CA Public Seismic Network San Jose http://www.publicseismicnetwork.com _________________ Logs pasted here ==================== Synchronize time successful from AT4 192.168.000.041[:37] Time RFC-868(TCP) 4/9/2005 4:11:48 PM.020000000 Leap:0 Stratum:2 ==================== Synchronize time error from Sunnyvale, CA, USA - 2 nist1.aol-ca.truetime.com[:123] SNTP RFC-1769/2030 ==================== Synchronize time successful from Sunnyvale, CA, USA - 2 nist1.aol-ca.truetime.com[207.200.81.113:123] SNTP RFC-1769/2030 4/9/2005 4:17:34 PM.453000000 Leap:0 Stratum:2 ==================== Synchronize time successful from HP 192.168.000.001[192.168.0.1:123] SNTP RFC-1769/2030 4/9/2005 4:26:26 PM.222000000 Leap:0 Stratum:2 ==================== ==================== --------------------------------- Help Text pasted here Client This tab sheet controls the client mode portion of Net Time Server & Client operation. Unicast mode: Set the client work in unicast (point to point) mode. a unicast client sends a request to a designated server at its unicast address and expects a reply from which it can determine the time and, optionally, the roundtrip delay and local clock offset relative to the server. Server: Specifies the time server name that will be used to run the synchronizations from. It is an arbitrary name assigned by you to represent the server when you create the time server settings. Edit...: Opens the "Edit time server settings" dialog box to modify the current time server settings. New...: Opens the "New time server settings" dialog box to create a new time server settings. Manager time servers...: Opens the "Manage time servers" dialog box to manage all time servers. Time out: Specifies a time to wait for a response from the time server. Time out(ms): Specifies how long you are willing to wait for a response from the time server (in millisecond). Retry times: Specifies how many times this server will retry the failed synchronization. Interval(sec): Specifies the number of seconds between two retries the failed synchronization. Automatic synchronization: Enables Net Time Server & Client to synchronize your system clock automatically. Interval(sec): Check this box, The Net Time Server & Client will repeat synchronization after a time period. You must specifies the number of second between two synchronization. Appointed time: Check this box, You must enter a time value, The Net Time Server & Client will automatically attempt to synchronize your system clock at this time. After program start-up: Check this box, The Net Time Server & Client will automatically attempt to synchronize your system clock once at it start-up. After create dial-up connection: Check this box, The Net Time Server & Client will automatically synchronize your system clock when it detects that dial-up networking or RAS has established a connection. Exits after synchornized: Check this box, The Net Time Server & Client will automatically terminate after successful synchronization. Exits even if attempt fails: When check the "Exits after synchornized" box, you can check this box, Enables Net Time Server & Client automatically terminate after synchronization even if it is fail. Manually synchronization: Synchronizes your system clock to selected time server manually (It cannot be disabled). Remote time: The box shows the time reported by the time Server. Get time: Requests the time from the time server. This time will be shown in the "Remote Time" box, but does not modify your system clock. Synchronize: Synchronizes your system clock to selected time server. Listen SNTP broadcast: Enables Net Time Server & Client to receive the SNTP broadcast from a multicast SNTP time server. The multicast SNTP time server periodically sends a unsolicited message to a designated local broadcast address or multicast group address and ordinarily expects no requests from clients. Note: If the listen port and the SNTP server port in "Server" tab sheet are the same, check the box will reset the Unicast box of SNTP server in "Server" tab sheet. Port: The SNTP time server broadcast port, the default is 123. Listen TimeUDP broadcast: Enables Net Time Server & Client to receive the Time(RFC-868) broadcast from a multicast Time(RFC-868) time server. The multicast Time(RFC-868) time server periodically sends a unsolicited message to a designated local broadcast address or multicast group address and ordinarily expects no requests from clients. Note: If the listen port and the TimeUDP(RFC-868) server port in "Server"tab sheet are the same, check the box will reset the Unicast box of TimeUDP(RFC-868) server in "Server" tab sheet. Port: The Time(RFC-868) time server broadcast port, the default is 37. Others: Other client options. Check synchronized flag: Check the box will cause Net Time Server & Client to accept a time stamp as valid, even if the server indicates it may not be valid. Check stratum: Check the box will cause Net Time to to accept a NTP time stamp as valid, even if the server stratum it may not be valid. The server stratum level is an indication sent with SNTP time stamps to show the level of accuracy of this system's clock. The SNTP specification allows a number from 1 to 15, with 1 being the most accurate. Notify when changes time: The option instructs Net Time Server & Client to send a notification message to all applications curently running notifying them that the system clock has changed. Contents Han-soft Software -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Keith Payea Sent: Saturday, April 09, 2005 1:53 PM To: psn-l@.............. Subject: RE: Network time standard Not all NTP clients are created equal... There are actually two standards. True NTP uses four time stamps to attempt to correct for transmission delays, and also runs a fairly complex filter based on many samples to set the time in your computer. Simple NTP (SNTP) uses just one time stamp, and is usually run once a day or every few hours with no filtering. Try to find an NTP that is based on the University of Delaware version. Dr. Mills at UDel is considered the true guru of NTP and his team have put many years into squeezing the best performance out of it. My experience when working for TrueTime (Now a division of Symmetricom) was that you could achieve 10 milliseconds or so if the server was not too far away on the public internet. If you run a local time service on your own network, the timing is much better than that. It usually takes several messages to get there due to the filtering. Also, true NTP will perform much better if you give it more than one server to work with. The software makes some attempt to evaluate the stability of each source and choose the best. Obviously, NTP is not as good as GPS, but it is very comparable to WWV or WWVB or DCF77 radio performance. Cheers, Keith ---------------------------------------------------------------------------- -- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Saturday, April 09, 2005 1:06 PM To: psn-l@.............. Subject: Re: Network time standard In a message dated 09/04/2005, shammon1@............. writes: If you don't have a GPS, as I said, the software comes with an extensive list of network time servers that can be accessed via the Internet to obtain accurate time. Overall, the experience with this software package has been very positive and after 30-days of testing I'm now recommending it to other members of the Public Seismic Network. Hi Steve, Does it give any timing accuracies in milli seconds for the various time servers? One of the problems with time services is that while the signal may leave the server on time, it may be digitally delayed on it's way though the telecom system. Since there are many services now operating, the inaccuracy around some timing marks may be very significant. What timing errors have you measured, please? About the Public NTP Time Server Lists The lists are provided for information purposes only and represent the best information available at the current date. The operators of the servers listed do not commit to provide time service other than on a volunteer basis and with no guarantee of accuracy or availability. Further information of a technical nature can be obtained from the www.ntp.org site, the comp.protocols.time.ntp newsgroup, or the NTP Support Web. Regards, Chris Chapman
Hi,  Remember, this is an = inexpensive=20 program. I cut and pasted the help documentation below the = logs just=20 below that. My home network is a 100 Mbs network with no traffic. I set = the time=20 out(ms) to 1ms and got a timeout error. I set it to 2ms and was able to = perform=20 the system synchronization. (See log entry for AT4) This implies that = the=20 two-way delay in my network is less than 2MS which is a reasonable = assumption. I=20 then pointed the software at the AOL time standard in San Jose CA and = was not=20 able to perform the system synchronization at 30 MS and received a = timeout=20 error and then was able to perform the system synchronization in 40 = ms.(See log=20 entry USA-2)  I was also able to connect and set the time. I then = configure=20 and connect to an HP 58503A GPS network time standard which = I also=20 have running in my network using the GPSCon software utility. I = configured=20 GPSCon as a time standard and was able to perform the system = synchronization=20 (See log message HP) The one think I did notice was that I had to up the = timeout=20 count on both systems after I started to broadcast the time = using the=20 HP time standard and  GPSCon software on my network. Because = of that,=20 I think there is some correlation to the decimal value in each of the = log=20 messages following the date time PM entry.  
 
I'll let you come to your own = conclusions. I=20 believe that to perform the system synchronization mean just that. There = is one=20 more issue which I think is also worth mentioning and it is the PC = system clock=20 is set by WinSDR on AT4.The GPSCon software is reading the time via a = Com port=20 connected to the HP58503A and acting as a network enabled time=20 standard. I'm certain there will be some loss of time in the=20 system activity on both AT1 the HP system and AT4 the system = running=20 WinSdr. Maybe Larry can comment. The Net Time service is dependent on = the PC=20 time on AT4 which is set by the GPS clock set system time function in = WinSDR. On=20 the HP system it is dependent on the system software application=20 GPScon.
 
Regards, Steve Hammond Aptos,=20 CA
Public Seismic Network San = Jose
http://www.publicseismicnetw= ork.com
 
_________________
Logs pasted here

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

Synchronize time successful from AT4

192.168.000.041[:37] Time RFC-868(TCP)

4/9/2005 4:11:48 PM.020000000 Leap:0 Stratum:2

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

Synchronize time error from Sunnyvale, CA, USA - 2

nist1.aol-ca.truetime.com[:123] SNTP RFC-1769/2030

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

Synchronize time successful from Sunnyvale, CA, USA - 2

nist1.aol-ca.truetime.com[207.200.81.113:123] SNTP RFC-1769/2030

4/9/2005 4:17:34 PM.453000000 Leap:0 Stratum:2

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

Synchronize time successful from HP

192.168.000.001[192.168.0.1:123] SNTP RFC-1769/2030

4/9/2005 4:26:26 PM.222000000 Leap:0 Stratum:2

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

 
 
---------------------------------
=
Help Text pasted here
Client
 

This tab sheet controls the client mode portion of Net Time = Server=20 & Client operation.
 
Unicast mode:
Set the client work in unicast (point to point) = mode. a=20 unicast client sends a request to a designated server at its unicast = address and=20 expects a reply from which it can determine the time and, optionally, = the=20 roundtrip delay and local clock offset relative to the server.
 
Server:
Specifies the time server name that will be used to run = the=20 synchronizations from. It is an arbitrary name assigned by you to = represent the=20 server when you create the time server settings.
 
Edit...:
Opens the "Edit time server settings" dialog box to = modify the=20 current time server settings.
 
New...:
Opens the "New time server settings" dialog box to = create a new=20 time server settings.
 
Manager time servers...:
 
Opens the "Manage time servers" dialog box to manage all time=20 servers.
 
Time out:
Specifies a time to wait for a response from the time=20 server.
 
Time out(ms):
Specifies how long you are willing to wait for a = response=20 from the time server (in millisecond).
 
Retry times:
Specifies how many times this server will retry the = failed=20 synchronization.
 
Interval(sec):
Specifies the number of seconds between two = retries the=20 failed synchronization.
 
Automatic synchronization:
Enables Net Time Server & Client = to=20 synchronize your system clock automatically.
 
Interval(sec):
Check this box, The Net Time Server & Client = will=20 repeat synchronization after a time period. You must specifies the = number of=20 second between two synchronization.
 
Appointed time:
Check this box, You must enter a time value, The = Net=20 Time Server & Client will automatically attempt to synchronize your = system=20 clock at this time.
 
After program start-up:
Check this box, The Net Time Server = & Client=20 will automatically attempt to synchronize your system clock once at it=20 start-up.
 
After create dial-up connection:
Check this box, The Net Time = Server=20 & Client will automatically synchronize your system clock when it = detects=20 that dial-up networking or RAS has established a connection.
 
Exits after synchornized:
Check this box, The Net Time Server = &=20 Client will automatically terminate after successful = synchronization.
 
Exits even if attempt fails:
When check the "Exits after = synchornized"=20 box, you can check this box, Enables Net Time Server & Client = automatically=20 terminate after synchronization even if it is fail.
 
Manually synchronization:
Synchronizes your system clock to = selected=20 time server manually (It cannot be disabled).
 
Remote time:
The box shows the time reported by the time = Server.
 
Get time:
Requests the time from the time server. This time = will be=20 shown in the "Remote Time" box, but does not modify your system = clock.
 
Synchronize:
Synchronizes your system clock to selected time=20 server.
 
Listen SNTP broadcast:
Enables Net Time Server & Client to = receive=20 the SNTP broadcast from a multicast SNTP time server. The multicast SNTP = time=20 server periodically sends a unsolicited message to a designated local = broadcast=20 address or multicast group address and ordinarily expects no requests = from=20 clients.
 
Note: If the listen port and the SNTP server port in "Server" tab = sheet are=20 the same, check the box will reset the Unicast box of SNTP server in = "Server"=20 tab sheet.
 
Port:
The SNTP time server broadcast port, the default is = 123.
 

Listen TimeUDP broadcast:
Enables Net Time Server & = Client to=20 receive the Time(RFC-868) broadcast from a multicast Time(RFC-868) time = server.=20 The multicast Time(RFC-868) time server periodically sends a unsolicited = message=20 to a designated local broadcast address or multicast group address and=20 ordinarily expects no requests from clients.
 
Note: If the listen port and the TimeUDP(RFC-868) server port in=20 "Server"tab sheet are the same, check the box will reset the Unicast box = of=20 TimeUDP(RFC-868) server in "Server" tab sheet.
 
Port:
The Time(RFC-868) time server broadcast port, the default = is=20 37.
 
Others:
Other client options.
 
Check synchronized flag:
 
Check the box will cause Net Time Server & Client to accept a = time=20 stamp as valid, even if the server indicates it may not be valid.
 
Check stratum:
 
Check the box will cause Net Time to to accept a NTP time stamp as = valid,=20 even if the server stratum it may not be valid. The server stratum level = is an=20 indication sent with SNTP time stamps to show the level of accuracy of = this=20 system's clock. The SNTP specification allows a number from 1 to 15, = with 1=20 being the most accurate.
 
Notify when changes time:
The option instructs Net Time Server = &=20 Client to send a notification message to all applications curently = running=20 notifying them that the system clock has changed.
 
Contents
 
Han-soft Software
-----Original Message-----
From:=20 psn-l-request@.............. = [mailto:psn-l-request@...............On Behalf=20 Of Keith Payea
Sent: Saturday, April 09, 2005 1:53=20 PM
To: psn-l@..............
Subject: RE: Network = time=20 standard

Not all = NTP clients are=20 created equal...  There are actually two standards.  True = NTP uses=20 four time stamps to attempt to correct for transmission delays, and = also runs=20 a fairly complex filter based on many samples to set the time in your=20 computer.  Simple NTP (SNTP) uses just one time stamp, and is = usually run=20 once a day or every few hours with no filtering.
 
Try to = find an NTP that=20 is based on the University of Delaware version.  Dr. Mills at = UDel is=20 considered the true guru of NTP and his team have put many years = into=20 squeezing the best performance out of it.
 
My = experience when=20 working for TrueTime (Now a division of Symmetricom) was that you = could=20 achieve 10 milliseconds or so if the server was not too far away on = the public=20 internet.  If you run a local time service on your own network, = the=20 timing is much better than that.  It usually takes several = messages to=20 get there due to the filtering.  Also, true NTP will perform much = better=20 if you give it more than one server to work with.  The software = makes=20 some attempt to evaluate the stability of each source and choose the=20 best.
 
Obviously, NTP is=20 not as good as GPS, but it is very comparable to WWV or WWVB or DCF77 = radio=20 performance.
 
Cheers,
 
Keith
 
 


From: psn-l-request@................. [mailto:psn-l-request@............... On Behalf Of=20 ChrisAtUpw@.......
Sent: Saturday, April 09, 2005 1:06=20 PM
To: psn-l@..............
Subject: Re: Network = time=20 standard

In a message dated 09/04/2005, shammon1@............. = writes:
If you don't = have a GPS, as=20 I said, the software comes with an extensive
list of network time = servers=20 that can be accessed via the Internet to obtain
accurate time. = Overall,=20 the experience with this software package has been
very positive = and=20 after 30-days of testing I'm now recommending it to other
members = of the=20 Public Seismic Network.
Hi Steve,
 
    Does it give any timing accuracies = in milli=20 seconds for the various time servers?
 
    One of the problems with time services is = that=20 while the signal may leave the server on time, it may be digitally = delayed on=20 it's way though the telecom system. Since there are many services now=20 operating, the inaccuracy around some timing marks may be very = significant.=20
 
    What timing errors have you measured,=20 please?
 
About the Public NTP Time Server Lists

The lists are provided for information purposes only and represent = the best=20 information available at the current date. The operators of the = servers listed=20 do not commit to provide time service other than on a volunteer basis = and with=20 no guarantee of accuracy or availability. Further information of a = technical=20 nature can be obtained from the www.ntp.org site, the comp.protocols.time.ntp newsgroup, or the NTP Support = Web.=20

    Regards,
 
    Chris Chapman
 
=
     
Subject: Re: first event From: Larry Cochrane lcochrane@.............. Date: Sat, 09 Apr 2005 21:07:21 -0700 Thanks great Bryan, nothing like keeping the pros on there toes.... -Larry Cochrane Redwood City, PSN 1goss@........... wrote: > I sent this to Center for Earthquake Research and Information (CERI) > And to my surprise got this response this was interesting + it is the first event I recorded on my Lehman seismometer. > > My letter to CERI : >> >I see an event that looks like a micro quake >> >on the Recent Helicorder Display >> >"http://folkworm.ceri.memphis.edu/heli_nm/" >> > PWLA EHZ NM : Pickwick Lake, AL > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Network time standard From: ChrisAtUpw@....... Date: Sun, 10 Apr 2005 00:15:28 EDT In a message dated 10/04/2005, shammon1@............. writes: My experience when working for TrueTime (Now a division of Symmetricom) was that you could achieve 10 milliseconds or so if the server was not too far away on the public internet. If you run a local time service on your own network, the timing is much better than that. It usually takes several messages to get there due to the filtering. Also, true NTP will perform much better if you give it more than one server to work with. The software makes some attempt to evaluate the stability of each source and choose the best. Hi Keith, I think that we maybe in danger of comparing grapes with bananas, if we are not careful. There is a fixed cycle time for the interrupt polling in a computer, both for the communications interface and for the program switching. Your multi tasking computer still only runs one program at a time - it just looks more capable since every cycle it polls a list to determine which are active. On one of the old IBM type computers that I checked, this was about every 10 milli sec, but it is likely to be more frequent on the current offerings. There are also different levels of interrupt priority. Then there are network response delays and digital transmission delays. Local phone networks are likely to be more accurate. I have measured transmission delays of 3 sec from the NIST clock over the internet to the 60 KHz radio time, but that was exceptional. The on line clock seems to have stated error bands of 0.5 to over 1.5 sec. I asked Steve what was the absolute accuracy that he had measured over the network time servers, but he didn't seem to fully understand my question. I quite believe that his own internal GPS network can detect a 1 mS error, but this is not an indication of how badly the network time servers and the communications programs are performing in practice. If you don't have a GPS, as I said, the software comes with an extensive list of network time servers that can be accessed via the Internet to obtain accurate time. Overall, the experience with this software package has been very positive and after 30-days of testing I'm now recommending it to other members of the Public Seismic Network. Does it give any timing accuracies in milli seconds for the various time servers? We do need to get a reasonable approximation to Universal Time, say better than 0.1 sec and this needs to be maintained at all times. We also need to remember that our filters can give very significant delays. A 6 pole 10 Hz Butterworth filter peaks at about 100 mS. A 6 pole 10 Hz Bessel gives about 40 mS. However, if you reduce the cut-off to 1.5 Hz, the figures are about 500 and 260 mS respectively. Part of this difference is the result of defining the cut-off as the 3 dB point, rather than matching up the ultimate slopes. The P waves may roll in at ~10 Km / sec. We wouldn't be having this discussion if computers were fitted with reasonably accurate clocks. The 4.194 MHz timing crystals can be trimmed to a few seconds per fortnight, but high precision temperature tracking modules can give 0.1 ppm. The lousy apology for a clock fitted to my current computer has drifted 8 sec in the last 2 hours. Even hourly updates would not give me anywhere near the precision required. You used to be able to buy boards with clock modules on them, but I haven't seen any about lately. Since you can get 60 KHz receiver modues and aerials, it would be helpful if A/D boards were able to read and update their clocks directly using WWVB signals. This should be maybe 1/3 the cost of a GPS system and you would not be dependant on having a permanent phone connection. Regards, Chris Chapman
In a message dated 10/04/2005, shammon1@............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>My experience when working for TrueTime (Now a=20 division of Symmetricom) was that you could achieve 10 milliseconds or so=20= if=20 the server was not too far away on the public internet.  If you run a= =20 local time service on your own network, the timing is much better than=20 that.  It usually takes several messages to get there due to the=20 filtering.  Also, true NTP will perform much better if you give it mo= re=20 than one server to work with.  The software makes some attempt to=20 evaluate the stability of each source and choose the=20 best.
Hi Keith,
 
    I think that we maybe in danger of comparing gr= apes=20 with bananas, if we are not careful. There is a fixed cycle time for the=20 interrupt polling in a computer, both for the communications interface and f= or=20 the program switching. Your multi tasking computer still only runs one progr= am=20 at a time - it just looks more capable since every cycle it polls a list to=20 determine which are active. On one of the old IBM type computers that I= =20 checked, this was about every 10 milli sec, but it is likely to be more= =20 frequent on the current offerings. There are also different levels of interr= upt=20 priority.
    Then there are network response delays and digi= tal=20 transmission delays. Local phone networks are likely to be more accurat= e. I=20 have measured transmission delays of 3 sec from the NIST clock over the inte= rnet=20 to the 60 KHz radio time, but that was exceptional. The on line clock s= eems=20 to have stated error bands of 0.5 to over 1.5 sec.   
 
    I asked Steve what was the absolute accuracy th= at=20 he had measured over the network time servers, but he didn't seem to fully=20 understand my question. I quite believe that his own internal GPS network ca= n=20 detect a 1 mS error, but this is not an=20 indication of how badly the network time servers and the=20 communications programs are performing in practice. 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If you=20 don't have a GPS, as I said, the software comes with an extensive
list=20= of=20 network time servers that can be accessed via the Internet to=20 obtain
accurate time. Overall, the experience with this software packag= e=20 has been
very positive and after 30-days of testing I'm now recommendin= g it=20 to other
members of the Public Seismic Network.
    Does it give any timing accuracies in mill= i=20 seconds for the various time servers?
 
    We do need to get a reasonable approximati= on=20 to Universal Time, say better than 0.1 sec and this needs to be maintained=20 at all times. We also need to remember that o= ur=20 filters can give very significant delays. A 6 pole 10 Hz Butterworth filter=20 peaks at about 100 mS. A 6 pole 10 Hz Bessel gives about 40 mS. However, if=20= you=20 reduce the cut-off to 1.5 Hz, the figures are about 500 and 260 mS respectiv= ely.=20 Part of this difference is the result of defining the cut-off as the 3=20= dB=20 point, rather than matching up the ultimate slopes. The P waves may roll in=20= at=20 ~10 Km / sec.
 
    We wouldn't be having this discussion if comput= ers=20 were fitted with reasonably accurate clocks. The 4.194 MHz timing crystals c= an=20 be trimmed to a few seconds per fortnight, but high precision temperature=20 tracking modules can give 0.1 ppm. The lousy apology for a clock fitted= to=20 my current computer has drifted 8 sec in the last 2 hours. Even hourly updat= es=20 would not give me anywhere near=20 the precision required. You used to be able to buy boards with clo= ck=20 modules on them, but I haven't seen any about lately.
 
    Since you can get 60 KHz receiver modues and=20 aerials, it would be helpful if A/D boards were able to read and update thei= r=20 clocks directly using WWVB signals. This should be maybe 1/3 the cost o= f a=20 GPS system and you would not be dependant on having a permanent phone=20 connection.
 
    Regards,
 
    Chris=20 Chapman    
Subject: RE: Network time standard From: "Steve Hammond" shammon1@............. Date: Sat, 9 Apr 2005 23:30:52 -0700 Hi Chris, sorry for note being more direct. >> Does it give any timing accuracies in milli seconds for the various time servers? To answer your question, no it does not. The best analysis I could provide you was within a few milliseconds which I know is not that accurate and that was by estimating and deduction as I stated. The software does not provide a means for that level of analysis. However, if you read the help file I attached, you will see that it attempts to determine the network delay and adjust the clock accordingly. It would be nice if the software posted the information or facilitated a means to measure it. But it does not. Once again I will state, because I'm certain you don't understand, this software package is a simple network time standard for keeping "all" the systems on your network in time. I now realized that any confusion is due to my weak usage statement. I think you believed that I intended the software to provide a detailed time standard for a seismic system without a GPS. I did not. I originally stated that the software was compatible with WinSDR using a Motorola GPS for providing a time standard for the PC's in your network. It has solved all my network time issues with having file dates and times over/under and even days off and I'm very happy with its compatibility with WinSDR. That's why I think it does the job. In reading your analysis below, I have to agree with you that the PC hardware impact the results and my experience tells me that every PC has been different and will drift accordingly. In the past, I used Right Time which had a self learning feature to help resolve PC clock drift. It accuracy was close, but no banana... When I converted to WinSDR, I thought I would use the HP 58503A. It has a frequency accuracy when locked to better than 1 X 10 to the -12th for a one day average from 0 to 50 degrees C. However, because of software incompatibility, when I configured the system to use this hardware time standard and the GPScon software to set the system clock, I was forced to configure WinSDR to use the system clock to obtain event timing. I found that the timing of the event files were drifting so badly that the data was unusable. The best solution I have found is to use an internally connected Motorola GPS, Larry's hardware package and WinSDR because it time stamps the data before it reaches the PC. Once I installed the Motorola GPS as Larry suggested I didn't have too many time issues with the seismic data. However occasionally for some unknown reason, the WinSDR software gets set to ADD mode and adds 4 or 5 min. to the data. I need to read the manual and see what I'm doing wrong. I must be hitting a button or somewhere along the way. But when its working correctly, the data timing is much better than anything I've ever used before. If you are interested in its accuracy, I know that Larry has done some work in this area and can provide the details. Again, sorry for any confusion I may have caused you, but I'm really happy with Net Time and its operational stability. I highly recommend it. Regards, Steve Hammond Aptos CA Public Seismic Network San Jose http://www.publicseismicnetwork.com -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Saturday, April 09, 2005 9:15 PM To: psn-l@.............. Subject: Re: Network time standard In a message dated 10/04/2005, shammon1@............. writes: My experience when working for TrueTime (Now a division of Symmetricom) was that you could achieve 10 milliseconds or so if the server was not too far away on the public internet. If you run a local time service on your own network, the timing is much better than that. It usually takes several messages to get there due to the filtering. Also, true NTP will perform much better if you give it more than one server to work with. The software makes some attempt to evaluate the stability of each source and choose the best. Hi Keith, I think that we maybe in danger of comparing grapes with bananas, if we are not careful. There is a fixed cycle time for the interrupt polling in a computer, both for the communications interface and for the program switching. Your multi tasking computer still only runs one program at a time - it just looks more capable since every cycle it polls a list to determine which are active. On one of the old IBM type computers that I checked, this was about every 10 milli sec, but it is likely to be more frequent on the current offerings. There are also different levels of interrupt priority. Then there are network response delays and digital transmission delays. Local phone networks are likely to be more accurate. I have measured transmission delays of 3 sec from the NIST clock over the internet to the 60 KHz radio time, but that was exceptional. The on line clock seems to have stated error bands of 0.5 to over 1.5 sec. I asked Steve what was the absolute accuracy that he had measured over the network time servers, but he didn't seem to fully understand my question. I quite believe that his own internal GPS network can detect a 1 mS error, but this is not an indication of how badly the network time servers and the communications programs are performing in practice. If you don't have a GPS, as I said, the software comes with an extensive list of network time servers that can be accessed via the Internet to obtain accurate time. Overall, the experience with this software package has been very positive and after 30-days of testing I'm now recommending it to other members of the Public Seismic Network. Does it give any timing accuracies in milli seconds for the various time servers? We do need to get a reasonable approximation to Universal Time, say better than 0.1 sec and this needs to be maintained at all times. We also need to remember that our filters can give very significant delays. A 6 pole 10 Hz Butterworth filter peaks at about 100 mS. A 6 pole 10 Hz Bessel gives about 40 mS. However, if you reduce the cut-off to 1.5 Hz, the figures are about 500 and 260 mS respectively. Part of this difference is the result of defining the cut-off as the 3 dB point, rather than matching up the ultimate slopes. The P waves may roll in at ~10 Km / sec. We wouldn't be having this discussion if computers were fitted with reasonably accurate clocks. The 4.194 MHz timing crystals can be trimmed to a few seconds per fortnight, but high precision temperature tracking modules can give 0.1 ppm. The lousy apology for a clock fitted to my current computer has drifted 8 sec in the last 2 hours. Even hourly updates would not give me anywhere near the precision required. You used to be able to buy boards with clock modules on them, but I haven't seen any about lately. Since you can get 60 KHz receiver modues and aerials, it would be helpful if A/D boards were able to read and update their clocks directly using WWVB signals. This should be maybe 1/3 the cost of a GPS system and you would not be dependant on having a permanent phone connection. Regards, Chris Chapman
Hi Chris, sorry for note being = more=20 direct.
 
   >> =  Does it=20 give any timing accuracies in milli seconds for the various time = servers?=20
 
 To answer your question, no = it does=20 not. The best analysis I could provide you was within a=20 few milliseconds which I know is not that accurate and that=20 was by estimating and deduction as I stated.  The=20 software does not provide a means for that level = of analysis.=20 However, if you read the help file I attached, you will see that it = attempts to=20 determine the network delay and adjust the clock accordingly. It would = be nice=20 if the software posted the information or facilitated a means to measure = it. But=20 it does not.
 
 Once again I will = state, because=20 I'm certain you don't understand, this software package is a simple = network=20 time standard for keeping "all" the systems on your network in time. I = now=20 realized that any confusion is due to my weak usage statement. I = think you=20 believed that I intended the software to provide a detailed time = standard for a=20 seismic system without a GPS. I did not. I originally stated that the = software=20 was compatible with WinSDR using a Motorola GPS for providing a time = standard=20 for the PC's in your network. It has solved all my network time = issues with=20 having file dates and times over/under and even days off and = I'm very happy=20 with its compatibility with WinSDR. That's why I think it does the=20 job. 
 
 In reading your analysis = below, I have=20 to agree with you that the PC hardware impact the results = and my=20 experience tells me that every PC has been different and will = drift=20 accordingly.  In the past, I used Right Time which had a = self=20 learning feature to help resolve PC clock drift. It accuracy was close, = but no=20 banana... When I converted to WinSDR, I thought I would use the HP = 58503A. It=20 has a frequency accuracy when locked to better than 1 X 10 to the -12th = for a=20 one day average from 0 to 50 degrees C. However, because of software=20 incompatibility, when I configured the system to use this hardware time = standard=20 and the GPScon software to set the system clock, I was forced=20 to configure WinSDR to use the system clock to = obtain event=20 timing. I found that the timing of the event files were = drifting so=20 badly that the data was unusable. The best solution I have found is = to=20 use an internally connected Motorola GPS, Larry's = hardware package and=20 WinSDR because it time stamps the data before it reaches the = PC. Once=20 I installed the Motorola GPS as Larry suggested I=20 didn't have too many time issues with the seismic data. = However=20 occasionally for some unknown reason, the WinSDR software gets set to = ADD mode=20 and adds 4 or 5 min. to the data. I need to read the manual and see what = I'm=20 doing wrong. I must be hitting a button or somewhere along the way. But = when its=20 working correctly, the data timing is much better than anything I've = ever used=20 before. If you are interested in its accuracy, I know that Larry has = done some=20 work in this area and can provide the details.
 
Again, sorry for any confusion I = may have=20 caused you, but I'm really happy with Net Time and its operational = stability. I=20 highly recommend it.
 
Regards, Steve Hammond Aptos = CA
Public Seismic Network  San=20 Jose
http://www.publicseismicnetw= ork.com
-----Original Message-----
From:=20 psn-l-request@.............. = [mailto:psn-l-request@...............On Behalf=20 Of ChrisAtUpw@.......
Sent: Saturday, April 09, 2005 = 9:15=20 PM
To: psn-l@..............
Subject: Re: Network = time=20 standard

In a message dated 10/04/2005, shammon1@............. = writes:
My experience when working for TrueTime = (Now a=20 division of Symmetricom) was that you could achieve 10 milliseconds = or so if=20 the server was not too far away on the public internet.  If you = run a=20 local time service on your own network, the timing is much better = than=20 that.  It usually takes several messages to get there due to = the=20 filtering.  Also, true NTP will perform much better if you give = it more=20 than one server to work with.  The software makes some attempt = to=20 evaluate the stability of each source and choose the=20 best.
Hi Keith,
 
    I think that we maybe in danger of = comparing=20 grapes with bananas, if we are not careful. There is a fixed cycle = time for=20 the interrupt polling in a computer, both for the communications = interface and=20 for the program switching. Your multi tasking computer still only runs = one=20 program at a time - it just looks more capable since every cycle it = polls a=20 list to determine which are active. On one of the old IBM type = computers=20 that I checked, this was about every 10 milli sec, but it is likely = to be=20 more frequent on the current offerings. There are also different = levels of=20 interrupt priority.
    Then there are network response delays = and=20 digital transmission delays. Local phone networks are likely to = be more=20 accurate. I have measured transmission delays of 3 sec from the NIST = clock=20 over the internet to the 60 KHz radio time, but that was = exceptional. The=20 on line clock seems to have stated error bands of 0.5 to over 1.5 = sec.   
 
    I asked Steve what was the absolute = accuracy that=20 he had measured over the network time servers, but he didn't seem to = fully=20 understand my question. I quite believe that his own internal GPS = network can=20 detect a 1 mS error, but this is not an=20 indication of how badly the network time servers and the = communications programs are performing in practice. 
If you don't = have a GPS, as=20 I said, the software comes with an extensive
list of network time = servers=20 that can be accessed via the Internet to obtain
accurate time. = Overall,=20 the experience with this software package has been
very positive = and=20 after 30-days of testing I'm now recommending it to other
members = of the=20 Public Seismic Network.
    Does it give any timing accuracies = in milli=20 seconds for the various time servers?
 
    We do need to get a reasonable = approximation=20 to Universal Time, say better than 0.1 sec and this needs to be = maintained=20 at all times. We also need to remember = that our=20 filters can give very significant delays. A 6 pole 10 Hz Butterworth = filter=20 peaks at about 100 mS. A 6 pole 10 Hz Bessel gives about 40 mS. = However, if=20 you reduce the cut-off to 1.5 Hz, the figures are about 500 and 260 mS = respectively. Part of this difference is the result of defining = the=20 cut-off as the 3 dB point, rather than matching up the ultimate = slopes. The P=20 waves may roll in at ~10 Km / sec.
 
    We wouldn't be having this discussion if=20 computers were fitted with reasonably accurate clocks. The 4.194 MHz = timing=20 crystals can be trimmed to a few seconds per fortnight, but high = precision=20 temperature tracking modules can give 0.1 ppm. The lousy apology = for a=20 clock fitted to my current computer has drifted 8 sec in the last 2 = hours.=20 Even hourly updates would not give me anywhere=20 near the precision required. You used to be = able to=20 buy boards with clock modules on them, but I haven't seen any about=20 lately.
 
    Since you can get 60 KHz receiver modues = and=20 aerials, it would be helpful if A/D boards were able to read and = update their=20 clocks directly using WWVB signals. This should be maybe 1/3 the = cost of=20 a GPS system and you would not be dependant on having a permanent = phone=20 connection.
 
    Regards,
 
    Chris=20 Chapman    
Subject: Re: Network time standard From: ian ian@........... Date: Sun, 10 Apr 2005 08:40:50 +0100 Hi, an interesting discussion. I note that a spec of <0.1 seconds has been mentioned (below). Could I ask, how is this derived? Apologies if this is documented somewhere on the psn site. I only ask because I know that using specs that are higher than needed can lead to costs that could have been avoided. I guess one would start by determining what is a reasonable error in calculating epicentre distance that can be tolerated and working back from there to derive a time spec. Another question is, which of the many factors influencing epicentre calculation is the limiting one? I would imagine that the average speed from the epicentre to a psn station would vary from station to station since each station is (obviously) located on a different part of the Earth and (presumably) the wave will travel through different parts of the Earth at a slightly different speed for each direction. If all the psn stations were locked in time to less than 0.1 seconds, then the average speed of the wave would have to be no worse than this for the data to benefit. For a teleseismic event which took, say, 15 minutes to arrive, all the "rays" would have to travel at the same average speed to within about 0.01% of each other. Is this possible?! Ian Smith ChrisAtUpw@....... wrote: > In a message dated 10/04/2005, shammon1@............. writes: > > My experience when working for TrueTime (Now a division of > Symmetricom) was that you could achieve 10 milliseconds or so if > the server was not too far away on the public internet. If you > run a local time service on your own network, the timing is much > better than that. It usually takes several messages to get there > due to the filtering. Also, true NTP will perform much better if > you give it more than one server to work with. The software makes > some attempt to evaluate the stability of each source and choose > the best. > > Hi Keith, > > I think that we maybe in danger of comparing grapes with bananas, > if we are not careful. There is a fixed cycle time for the interrupt > polling in a computer, both for the communications interface and for > the program switching. Your multi tasking computer still only runs one > program at a time - it just looks more capable since every cycle it > polls a list to determine which are active. On one of the old IBM type > computers that I checked, this was about every 10 milli sec, but it is > likely to be more frequent on the current offerings. There are also > different levels of interrupt priority. > Then there are network response delays and digital transmission > delays. Local phone networks are likely to be more accurate. I have > measured transmission delays of 3 sec from the NIST clock over the > internet to the 60 KHz radio time, but that was exceptional. The on > line clock seems to have stated error bands of 0.5 to over 1.5 sec. > > I asked Steve what was the absolute accuracy that he had measured > over the network time servers, but he didn't seem to fully understand > my question. I quite believe that his own internal GPS network can > detect a 1 mS error, but this is not an indication of how badly the > network time servers and the communications programs are performing in > practice. > > If you don't have a GPS, as I said, the software comes with an > extensive > list of network time servers that can be accessed via the Internet > to obtain > accurate time. Overall, the experience with this software package > has been > very positive and after 30-days of testing I'm now recommending it > to other > members of the Public Seismic Network. > > Does it give any timing accuracies in milli seconds for the > various time servers? > > We do need to get a reasonable approximation to Universal Time, > say better than 0.1 sec and this needs to be maintained at all times. > We also need to remember that our filters can give very significant > delays. A 6 pole 10 Hz Butterworth filter peaks at about 100 mS. A 6 > pole 10 Hz Bessel gives about 40 mS. However, if you reduce the > cut-off to 1.5 Hz, the figures are about 500 and 260 mS respectively. > Part of this difference is the result of defining the cut-off as the 3 > dB point, rather than matching up the ultimate slopes. The P waves may > roll in at ~10 Km / sec. > > We wouldn't be having this discussion if computers were fitted > with reasonably accurate clocks. The 4.194 MHz timing crystals can be > trimmed to a few seconds per fortnight, but high precision temperature > tracking modules can give 0.1 ppm. The lousy apology for a clock > fitted to my current computer has drifted 8 sec in the last 2 hours. > Even hourly updates would not give me anywhere near the precision > required. You used to be able to buy boards with clock modules on > them, but I haven't seen any about lately. > > Since you can get 60 KHz receiver modues and aerials, it would be > helpful if A/D boards were able to read and update their clocks > directly using WWVB signals. This should be maybe 1/3 the cost of a > GPS system and you would not be dependant on having a permanent phone > connection. > > Regards, > > Chris Chapman Hi,

an interesting discussion.  I note that a spec of  <0.1 seconds has been mentioned (below).  Could I ask, how is this derived?  Apologies if this is documented somewhere on the psn site.

I only ask because I know that using specs that are higher than needed can lead to costs that could have been avoided.  I guess one would start by determining what is a reasonable error in calculating epicentre distance that can be tolerated and working back from there to derive a time spec.

Another question is, which of the many factors influencing epicentre calculation is the limiting one?  I would imagine that the average speed from the epicentre to a psn station would vary from station to station since each station is (obviously) located on a different part of the Earth and (presumably) the wave will travel through different parts of the Earth at a slightly different speed for each direction. 

If all the psn stations were locked in time to less than 0.1 seconds, then the average speed of the wave would have to be no worse than this for the data to benefit.  For a teleseismic event which took, say, 15 minutes to arrive, all the "rays" would have to travel at the same average speed to within about 0.01% of each other.  Is this possible?!

Ian Smith

ChrisAtUpw@....... wrote:
In a message dated 10/04/2005, shammon1@............. writes:
My experience when working for TrueTime (Now a division of Symmetricom) was that you could achieve 10 milliseconds or so if the server was not too far away on the public internet.  If you run a local time service on your own network, the timing is much better than that.  It usually takes several messages to get there due to the filtering.  Also, true NTP will perform much better if you give it more than one server to work with.  The software makes some attempt to evaluate the stability of each source and choose the best.
Hi Keith,
 
    I think that we maybe in danger of comparing grapes with bananas, if we are not careful. There is a fixed cycle time for the interrupt polling in a computer, both for the communications interface and for the program switching. Your multi tasking computer still only runs one program at a time - it just looks more capable since every cycle it polls a list to determine which are active. On one of the old IBM type computers that I checked, this was about every 10 milli sec, but it is likely to be more frequent on the current offerings. There are also different levels of interrupt priority.
    Then there are network response delays and digital transmission delays. Local phone networks are likely to be more accurate. I have measured transmission delays of 3 sec from the NIST clock over the internet to the 60 KHz radio time, but that was exceptional. The on line clock seems to have stated error bands of 0.5 to over 1.5 sec.   
 
    I asked Steve what was the absolute accuracy that he had measured over the network time servers, but he didn't seem to fully understand my question. I quite believe that his own internal GPS network can detect a 1 mS error, but this is not an indication of how badly the network time servers and the communications programs are performing in practice. 
If you don't have a GPS, as I said, the software comes with an extensive
list of network time servers that can be accessed via the Internet to obtain
accurate time. Overall, the experience with this software package has been
very positive and after 30-days of testing I'm now recommending it to other
members of the Public Seismic Network.
    Does it give any timing accuracies in milli seconds for the various time servers?
 
    We do need to get a reasonable approximation to Universal Time, say better than 0.1 sec and this needs to be maintained at all times. We also need to remember that our filters can give very significant delays. A 6 pole 10 Hz Butterworth filter peaks at about 100 mS. A 6 pole 10 Hz Bessel gives about 40 mS. However, if you reduce the cut-off to 1.5 Hz, the figures are about 500 and 260 mS respectively. Part of this difference is the result of defining the cut-off as the 3 dB point, rather than matching up the ultimate slopes. The P waves may roll in at ~10 Km / sec.
 
    We wouldn't be having this discussion if computers were fitted with reasonably accurate clocks. The 4.194 MHz timing crystals can be trimmed to a few seconds per fortnight, but high precision temperature tracking modules can give 0.1 ppm. The lousy apology for a clock fitted to my current computer has drifted 8 sec in the last 2 hours. Even hourly updates would not give me anywhere near the precision required. You used to be able to buy boards with clock modules on them, but I haven't seen any about lately.
 
    Since you can get 60 KHz receiver modues and aerials, it would be helpful if A/D boards were able to read and update their clocks directly using WWVB signals. This should be maybe 1/3 the cost of a GPS system and you would not be dependant on having a permanent phone connection.
 
    Regards,
 
    Chris Chapman    
Subject: time issue From: "Thomas Dick" dickthomas01@............. Date: Sun, 10 Apr 2005 11:27:56 -0500 I have followed this discussion with interest. I used a time sync = program before I got into seismology -- almost ten years ago. Syncing a = local network is a lot easier than time syncing WinSDR. One of the = drawbacks of using Internet sources to set time is that the source is = not available all the time. Maybe, your provider isn't doing maintenance = or isn't slowed down by heavy demand like mine is at times or the = provider may even be shut down by viruses or mechanical problems in the = lines or center computer breakdown. Certainly access to a time source = will NOT be as dependable as you think. Chris has a point, too, about the computer we use with the detection = equipment. I doubt many of you use the newest computer to run WinSDR -- = it is overkill. But the older computers ARE slow to multitask and their = clocks are not that stable. I don't see Larry's GPS board that big an = expense for the accuracy it provides plus it is easy to install. I might also add that variations in dependability in over-the-air = reception should be expected as well; there is day-to-night, sun spot = interference -- even the arrival of long path-short path signals at the = same time and place can be a problem . There is also human created noise = such as power generators that carpenters use to power tools at = construction sites, even legal amateur radio broadcasting, broken = insulators on nearby power poles and by all means drift in the receivers = being used to capture time pulses over the air. GPS is best for no other reason that it operates in frequencies above = the normal interferences -- it comes from straight up there -- with no = bending over the horizon
I have followed this discussion with = interest. I=20 used a time sync program before I got into seismology -- almost ten = years ago.=20 Syncing a local network is a lot easier than time syncing WinSDR. One of = the=20 drawbacks of using Internet sources to set time is that the source is = not=20 available all the time. Maybe, your provider isn't doing maintenance or = isn't=20 slowed down by heavy demand like mine is at times or the = provider may=20 even be shut down by viruses or mechanical problems in the lines or = center=20 computer breakdown. Certainly access to a time source will NOT be as = dependable=20 as you think.
 
Chris has a point, too, about the = computer we use=20 with the detection equipment. I doubt many of you use the newest = computer=20 to run WinSDR -- it is overkill. But the older computers ARE slow to = multitask=20 and their clocks are not that stable. I don't see Larry's GPS board that = big an=20 expense for the accuracy it provides plus it is easy to = install.
 
I might also add that variations in = dependability=20 in over-the-air reception should be expected as well; there is = day-to-night, sun=20 spot interference -- even the arrival of long path-short path signals at = the=20 same time and place can be a problem . There is also human = created=20 noise such as power generators that carpenters use to power tools at=20 construction sites, even legal amateur radio broadcasting, broken = insulators on=20 nearby power poles and by all means drift in the receivers being = used to=20 capture time pulses over the air.
 
GPS is best for no other reason that it = operates in=20 frequencies above the normal interferences -- it comes from straight up = there --=20 with no bending over the horizon
 
Subject: Re: time issue From: Bobhelenmcclure@....... Date: Sun, 10 Apr 2005 22:25:16 EDT I depend indirectly on WWVB via an "atomic" wall clock for timing. I use a DI-194 Dataq A/D for data recording. This device allows event marks to be placed on the recorded data, and I use the clock to pick off minute marks. I am very satisfied with my setup, but I do not know if it could be readily adapted to WinSDR. Please take a look at: http://www.jclahr.com/science/psn/mcclure/timing/index.html and tell me what you think. I avoid the time delay distortion normally encountered with filtering by using my application called "WQFilter.exe", which uses low-pass filters of my own design. These filters are applied both forward and backward in time. They therefore do not work in real time, but are useful in preparing WinQuake event files. This application can be downloaded from http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html It is contained in the ZIP file "seismic_dataq.zip". It works with PSN Type 4 files. It also has a filter which digitally extends the long period response of my sensors, which have natural periods of only 6, 8, and 13 seconds, respectively. I use it to prepare all my event files from station REM, Locust Valley, NY. My prepared waveforms compare very closely with those from the nearby LDEO station PAL. Real-time and archival drum plots from PAL can be seen at: http://www.ldeo.columbia.edu/cgi-bin/LCSN/WebSeis/24hr_heli.pl?id= Regards, Bob McClure   I depend indirectly on WWVB=20= via an "atomic" wall clock for timing. I use a DI-194 Dataq A/D for data rec= ording. This device allows event marks to be placed on the recorded data, an= d I use the clock to pick off minute marks. I am very satisfied with my setu= p, but I do not know if it could be readily adapted to WinSDR. Please take a= look at:

  http://www.jclahr.com/science/psn/mcclure/timing/index.html

and tell me what you think.

  I avoid the time delay distortion normally encountered with filtering= by using my application called "WQFilter.exe", which uses low-pass filters=20= of my own design. These filters are applied both forward and backward in tim= e. They therefore do not work in real time, but are useful in preparing WinQ= uake event files.

  This application can be downloaded from

  http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html
  It is contained in the ZIP file "seismic_dataq.zip". It works with PS= N Type 4 files. It also has a filter which digitally extends the long period= response of my  sensors, which have natural periods of only 6, 8, and=20= 13 seconds, respectively. I use it to prepare all my event files from statio= n REM, Locust Valley, NY. My prepared waveforms compare very closely with th= ose from the nearby LDEO station PAL. Real-time and archival drum plots from= PAL can be seen at:

  http://www.ldeo.columbia.edu/cgi-bin/LCSN/WebSeis/24hr_heli.pl?id=3D<= BR>
Regards,

Bob McClure
Subject: Re: Network time standard From: ChrisAtUpw@....... Date: Sun, 10 Apr 2005 23:52:01 EDT In a message dated 10/04/2005, ian@........... writes: Hi, an interesting discussion. I note that a spec of <0.1 seconds has been mentioned (below). Could I ask, how is this derived? Apologies if this is documented somewhere on the psn site. Hi Ian, It is very simple. You have to determine the start of the P wave signal which is of the order of 1 Hz against a noisy background. Local P waves may also have higher frequency components added in. There may also be uncertainties in the filter delay, particularly if you use Butterworth filters. The delay in Bessel filters is shorter and better defined. This accuracy of wave timing should be achievable by amateur seismologists in practice. I only ask because I know that using specs that are higher than needed can lead to costs that could have been avoided. I guess one would start by determining what is a reasonable error in calculating epicentre distance that can be tolerated and working back from there to derive a time spec. I agree that you can't use the sub microsecond accuracy of a good GPS clock. However, if your clock only had an accuracy of 1 sec, you would have a possible error of ~10 km. If it had an error of 10 sec, the possible error is ~100 km. Neither would be particularly helpful when estimating the depth of a quake at, say 40 km, or of it's position. I'm sorry to put it so bluntly, but if you CAN'T give error limits to your measurements, you are JUST COLLECTING GARBAGE ! If your signals are to have any value, you cannot accept a cumulative timing error which builds up in an unknown way to the equivalent of many kms uncertainty - eg a rubbishy timing system. Another question is, which of the many factors influencing epicentre calculation is the limiting one? I would imagine that the average speed from the epicentre to a psn station would vary from station to station since each station is located on a different part of the Earth and the wave will travel through different parts of the Earth at a slightly different speed for each direction. If all the psn stations were locked in time to less than 0.1 seconds, then the average speed of the wave would have to be no worse than this for the data to benefit. For a teleseismic event which took, say, 15 minutes to arrive, all the "rays" would have to travel at the same average speed to within about 0.01% of each other. Is this possible?! Sure. You do not seem to be thinking correctly about the problem. Let's put the measurements in context. With a P wave velocity to ~10 km / sec, it takes under an hour for the wave to traverse the earth. At a frequency of 1 Hz, the wavelength is about 10 km. Structures which are smaller than this will not effect the transmission significantly at any great distance. The wave path traverses regions of the Earth which have different velocities and the track is inevitably curved. What you observe with the seismometer is the 'net result at one observation point'. But this signal may be modified significantly by the local sub surface geology. Under favourable conditions, you can measure the time difference between the P & S waves and get a rough estimate of the distance to the source, but only if you can make 'reasonable' assumptions about the average wave velocities. The location programme then has the job of reverse tracing the waves to the source, for several seismometer responses at different places and getting the best overall 'fit'. The average travel / time curves that you have seen give the first approximation to this relationship and THEY ARE CURVES - you do NOT have straight line relationships. See the AmaSeis overplots. Moreover, each seismometer location and wave direction may have slightly different properties depending on the sub surface geology - the curves are only averaged values. We wouldn't be having this discussion if computers were fitted with reasonably accurate clocks. The 4.194 MHz timing crystals can be trimmed to a few seconds per fortnight, but high precision temperature tracking modules can give 0.1 ppm. The 32 kHz crystals often found in watches are much more temperature sensitive. The lousy apology for a clock fitted to my current computer drifted 8 sec in the first 2 hours and was down 28 sec on a day. Even hourly web updates would not give me anywhere near the precision required. You used to be able to buy input expansion boards with clock modules on them, but I haven't seen any about lately. Since you can get 60 KHz receiver modules and aerials, it would be helpful if A/D boards were able to read and update their clocks directly using WWVB signals. This should be maybe 1/3 the cost of a GPS system and you would not be dependant on having a permanent phone connection. Perhaps Larry could stock them? The A/D board that I use has the timing and radio signal synchronisation built into it's microprocessor. It has a low drift A/T cut crystal, which is frequency trimmed. It is not inside the hot computer case. The microprocessor is set for hourly radio updates and there is a lock idicator to confirm the update status. I can periodically sync the computer clock with the board or with the net, but I am not dependant on the computer software clock, or on a permanent net connection, for accurate timing and sampling. I bought a 60 KHz radio corrected digital quartz crystal clock and it has been a very valuable reference for the station. I can thoroughly recommend them. Regards, Chris Chapman
In a message dated 10/04/2005, ian@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Hi,
an interesting discussion.  I note that a spec of <= ;0.1=20 seconds has been mentioned (below).  Could I ask, how is this=20 derived?  Apologies if this is documented somewhere on the psn=20 site.
Hi Ian,
 
    It is very simple. You have to determine the st= art=20 of the P wave signal which is of the order of 1 Hz against a noisy=20 background. Local P waves may also have higher frequency components add= ed=20 in.  There may also be uncertainties in the filter delay, particularly=20= if=20 you use Butterworth filters. The delay in Bessel filters is shorter and bett= er=20 defined. This accuracy of wave timing should be achievable by amateur=20 seismologists in practice.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>    I only ask because I know that using spec= s that=20 are higher than needed can lead to costs that could have been avoided.&nbs= p; I=20 guess one would start by determining what is a reasonable error in calcula= ting=20 epicentre distance that can be tolerated and working back from there to de= rive=20 a time spec.
    I agree that you can't use the sub microsecond=20 accuracy of a good GPS clock. However, if your clock only had an accuracy of= 1=20 sec, you would have a possible error of ~10 km. If it had an error of 10 sec= ,=20 the possible error is ~100 km. Neither would be particularly helpful when=20 estimating the depth of a quake at, say 40 km, or of it's position. I'm sorr= y to=20 put it so bluntly, but if you CAN'T give error limits to your=20 measurements, you are JUST COLLECTING GARBAGE !
 
    If your signals are to have any value,=20 you cannot accept a cumulative timing error which=20 builds up in an unknown way to the equivalent of=20 many kms uncertainty - eg a rubbishy timing=20 system.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>    Another question is, which of the many fa= ctors=20 influencing epicentre calculation is the limiting one?  I would imagi= ne=20 that the average speed from the epicentre to a psn station would vary from= =20 station to station since each station is located on a different part of th= e=20 Earth and the wave will travel through different parts of the Earth at a=20 slightly different speed for each=20 direction.  

    If all the psn stati= ons=20 were locked in time to less than 0.1 seconds, then the average speed of th= e=20 wave would have to be no worse than this for the data to benefit.  Fo= r a=20 teleseismic event which took, say, 15 minutes to arrive, all the "rays" wo= uld=20 have to travel at the same average speed to within about 0.01% of each=20 other.  Is this possible?!
    Sure. You do not seem to be thinking corre= ctly=20 about the problem. Let's put the measurements in context. With a P wave velo= city=20 to ~10 km / sec, it takes under an hour for the wave to traverse the=20 earth. At a frequency of 1 Hz, the wavelength is about 10 km. Structure= s=20 which are smaller than this will not effect the transmission significantly a= t=20 any great distance. The wave path traverses regions of the Earth which have=20 different velocities and the track is inevitably curved. What you observe wi= th=20 the seismometer is the 'net result at one observation point'. Bu= t=20 this signal may be modified significantly by the local sub surface geology.=20
    Under favourable conditions, you can measu= re=20 the time difference between the P & S waves and get a rough=20 estimate of the distance to the source, but only if you can make=20 'reasonable' assumptions about the average wave velocities. The location=20 programme then has the job of reverse tracing the waves to the source, for=20 several seismometer responses at different places and getting the best=20 overall 'fit'. The average travel / time curves that you have seen give= the=20 first approximation to this relationship and THEY ARE CURVES - you do N= OT=20 have straight line relationships. See the AmaSeis overplots. Moreover, each=20 seismometer location and wave direction may have slightly different properti= es=20 depending on the sub surface geology - the curves are only averaged=20 values.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
    We wouldn't be having this discussion if=20 computers were fitted with reasonably accurate clocks. The 4.194 MHz tim= ing=20 crystals can be trimmed to a few seconds per fortnight, but high precisi= on=20 temperature tracking modules can give 0.1 ppm. The 32 kHz crystals=20 often found in watches are much more temperature=20 sensitive.          &n= bsp;            =   =20 The lousy apology for a clock fitted to my current computer drifted= 8=20 sec in the first 2 hours and was down 28 sec on a day. Even=20 hourly web updates would not give me anywhere near the precisi= on=20 required. You used to be able to buy input expansion=20 boards with clock modules on them, but I haven't seen any about=20 lately.
 
    Since you can get 60 KHz receiver modules a= nd=20 aerials, it would be helpful if A/D boards were able to read and update=20 their clocks directly using WWVB signals. This should be maybe 1/3=20= the=20 cost of a GPS system and you would not be dependant on having a permanen= t=20 phone connection.
    Perhaps Larry could stock them?
 
    The A/D board that I use has the timing and rad= io=20 signal synchronisation built into it's microprocessor. It has a low d= rift=20 A/T cut crystal, which is frequency trimmed. It is not inside the hot comput= er=20 case. The microprocessor is set for hourly radio updates and there is a lock= =20 idicator to confirm the update status. I can periodically sync the computer=20 clock with the board or with the net, but I am not=20 dependant on the computer software clock, or on a permanent ne= t=20 connection, for accurate timing and sampling.
 
    I bought a 60 KHz radio corrected digital quart= z=20 crystal clock and it has been a very valuable reference for the station. I c= an=20 thoroughly recommend them. 
 
    Regards,
 
    Chris Chapman
 
    
Subject: Re: time issue From: ChrisAtUpw@....... Date: Mon, 11 Apr 2005 00:14:51 EDT In a message dated 10/04/2005, dickthomas01@............. writes: Chris has a point, too, about the computer we use with the detection equipment. I doubt many of you use the newest computer to run WinSDR -- it is overkill. But the older computers ARE slow to multitask and their clocks are not that stable. I don't see Larry's GPS board that big an expense for the accuracy it provides plus it is easy to install. I might also add that variations in dependability in over-the-air reception should be expected as well; there is day-to-night, sun spot interference -- even the arrival of long path-short path signals at the same time and place can be a problem. There is also human created noise such as power generators that carpenters use to power tools at construction sites, even legal amateur radio broadcasting, broken insulators on nearby power poles and by all means drift in the receivers being used to capture time pulses over the air. In my limited experience, new computers seem to be even less reliable for clock accuracy than older ones. These seem to be more problems that I would associate with WWV signals. WWVB may be a lot more reliable and my 60 KHz module has a crystal filter. I have checked it for operation up to 1800 miles. GPS is best for no other reason that it operates in frequencies above the normal interferences -- it comes from straight up there -- with no bending over the horizon Assuming that you have clear vision to the satellites and no trees or power lines in the way.... But GPS costs roughly 3x as much as a radio module + aerial. Regards, Chris Chapman
In a message dated 10/04/2005, dickthomas01@............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Chris has a point, too, about the compute= r we use=20 with the detection equipment. I doubt many of you use the newest comp= uter=20 to run WinSDR -- it is overkill. But the older computers ARE slow to multi= task=20 and their clocks are not that stable. I don't see Larry's GPS board that b= ig=20 an expense for the accuracy it provides plus it is easy to=20 install.
 
I might also add that variations in depen= dability=20 in over-the-air reception should be expected as well; there is day-to-nigh= t,=20 sun spot interference -- even the arrival of long path-short path signals=20= at=20 the same time and place can be a problem. There is also human created= =20 noise such as power generators that carpenters use to power tools at=20 construction sites, even legal amateur radio broadcasting, broken insulato= rs=20 on nearby power poles and by all means drift in the receivers being u= sed=20 to capture time pulses over the air.
    In my limited experience, new computers seem to= be=20 even less reliable for clock accuracy than older ones.
 
    These seem to be more problems that I would=20 associate with WWV signals. WWVB may be a lot more reliable and my 60 K= Hz=20 module has a crystal filter. I have checked it for operation up to 1800=20 miles.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
GPS is best for no other reason that it o= perates=20 in frequencies above the normal interferences -- it comes from straight up= =20 there -- with no bending over the horizon
    Assuming that you have clear vision to the=20 satellites and no trees or power lines in the way.... But GPS costs roughly=20= 3x=20 as much as a radio module + aerial.
 
    Regards,
 
    Chris Chapman
Subject: On timing From: Kevin McCue asc@............... Date: Mon, 11 Apr 2005 14:17:51 +1000 Reluctant as I was to get involved in a good story,=A0=A0Chris=20 Chapman=A0=A0finally got me in with: '=A0I agree that you can't use the sub microsecond accuracy of a good = GPS=20 clock. However, if your clock only had an accuracy of 1 sec, you would=20= have a possible error of ~10 km. If it had an error of 10 sec, the=20 possible error is ~100 km. Neither would be particularly helpful when=20 estimating the depth of a quake at, say 40 km, or of it's position. I'm=20= sorry to put it so bluntly, but if you CAN'T give error limits to your=20= measurements, you are JUST COLLECTING GARBAGE !' You can use S-P intervals to locate the epicentre, travel time curves=20 to compute an origin time and depth-phase identification to sort out=20 focal depth - one could get away without accurate time at all, but it=20 makes life easier. Cheers Kevin Kevin McCue Director Australian Seismological Centre PO Box 324 Jamison Centre ACT 2614 Australia ph: 61 (0)2 6251 1291= __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Network time standard From: Angel sismos@.............. Date: Mon, 11 Apr 2005 06:31:39 -0500 Hi, I have come in a little late on this very interesting time thread. Windows has the ability to be synchronized by another computer on the same network. If you you have a windows box with good time you can slave other to it with the command, (make it a batch file) nettime \\computer_with_good_time / set / yes Replacing "computer_with_good_time" with the network name of the computer who has good time, the one with the GPS or whatever. Here is a page with some detailed instructions. http://www.wown.com/j_helmig/nettime.htm It's nothing fancy but it works. I use it, I don't know how "accurate" it is. Regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Network time standard From: "Keith Payea" kpayea@........... Date: Mon, 11 Apr 2005 09:53:10 -0700 I use NTPTime: http://home.att.net/~Tom.Horsley/ntptime.html, which I found by visiting www.ntp.org and looking for Windows 2k compatible builds of NTP. If you are looking for a Linux version, there are many. Go to ntp.org and poke around. According to the log files, NTPTime is checking once an hour, and it is adjusting the clock about +- 20 mS each time. My computer is always on, and I have DSL, so it can check whenever it wants. However, my "Office" has no temperature control, so NTPTime is able to deal with that fairly well. For the purposes of seismic monitoring, I'm assuming the computer is always on. Someone mentioned how bad the time is when the computer is off. Also, there was some mention of Millenium Edition. If you can manage it, dump that in favor of something else. Even Microsoft admits it was not their finest effort..... There are also problems with Microsoft's implementation of NTP in Windows. They have ignored the standard in a couple of places, so it can't get time from some of the public servers. AboutTime cited below appears to be an SNTP client, which also supports some of the older (TIME and DAYTIME) protocols. It's fine for getting you to a second or better. As I mentioned in my previous post, a good NTP implementation will compensate somewhat for transmission delays. This is done by using four time stamps: 1) at the time the request is sent, 2) at the time the request is received, 3) at the time the response is sent, 4) at the time the response is received. The NTP packet has room for all four, so the client gets them all back. From that, the bulk of the transmission time can be removed, and the true offset between the client and the server can be calculated. Things that cause it problems are if the message takes a radically different route in each direction. The odds of this happening increase with distance, so that's why a nearer time server is a better choice than a "better" server that is farther away. Routing changes relatively slowly based on demand. This is also why the best implementations need to filter the offset over several messages. They then adjust the system clock speed (not the crystal, just the interrupt rate!) to compensate - they don't just jam the new time into the clock. Before flaming me about any of my simplifications, remember to check www.ntp.org and read through their stuff. They have put a huge amount of work into solving this problem while working around the OS limitations. Keith -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of John or Jan Lahr Sent: Saturday, April 09, 2005 4:51 PM To: psn-l@.............. Subject: RE: Network time standard At 02:53 PM 4/9/2005, Keith wrote: >Not all NTP clients are created equal... In your experience, which is the best, free time-sync software for a PC with an Internet connection but no local time server. Can you evaluate AboutTime: http://www.arachnoid.com/abouttime/ ? Thanks, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: On timing From: ChrisAtUpw@....... Date: Mon, 11 Apr 2005 22:03:12 EDT In a message dated 11/04/2005, asc@............... writes: Reluctant as I was to get involved in a good story, Chris Chapman finally got me in with: ' I agree that you can't use the sub microsecond accuracy of a good GPS clock. However, if your clock only had an accuracy of 1 sec, you would have a possible error of ~10 km. If it had an error of 10 sec, the possible error is ~100 km. Neither would be particularly helpful when estimating the depth of a quake at, say 40 km, or of it's position. I'm sorry to put it so bluntly, but if you CAN'T give error limits to your measurements, you are JUST COLLECTING GARBAGE !' You can use S-P intervals to locate the epicentre, travel time curves to compute an origin time and depth-phase identification to sort out focal depth - one could get away without accurate time at all, but it makes life easier. Cheers Kevin Kevin McCue Director Australian Seismological Centre Dear Dr McCue, Thank you for your comment! I am not sure if you have appreciated quite how erratic computer software clocks can be? Let's say that we have three amateur stations which know their Lat and Long co-ordinates, but are each only 50 km apart in a roughly straight line in a UK setting. My clock lost 6 sec per hour and the central station gained 6 sec per hour when checked last week, but the other end one is unknown. We are all using the standard Widows clock update of once per week and are at the end of the cycle. We all measure a P / S delay times of the order of 10 min, but we have only the one vertical sensor with some cross sensitivity. Sure we can put in figures for the average travel times for a range of depths, but estimating a 'cocked hat position' and working back to the time of origin leaves several minutes unexplained. How do you suggest that we get an estimate of the time, location and depth of the quake and the probable errors, please? Regards, Chris Chapman
In a message dated 11/04/2005, asc@............... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Reluctant as I was to get involved in a good story, Chris=20
Chapman  finally got me in with:

' I agree that=20= you=20 can't use the sub microsecond accuracy of a good GPS
clock. However, i= f=20 your clock only had an accuracy of 1 sec, you would
have a possible er= ror=20 of ~10 km. If it had an error of 10 sec, the
possible error is ~100 km= ..=20 Neither would be particularly helpful when
estimating the depth of a q= uake=20 at, say 40 km, or of it's position. I'm
sorry to put it so bluntly, bu= t if=20 you CAN'T give error limits to your
measurements, you are JUST COLLECT= ING=20 GARBAGE !'

You can use S-P intervals to locate the epicentre, trave= l=20 time curves
to compute an origin time and depth-phase identification t= o=20 sort out
focal depth - one could get away without accurate time at all= ,=20 but it
makes life easier.
Cheers
Kevin

Kevin=20 McCue
Director
Australian Seismological=20 Centre
Dear Dr McCue,
 
    Thank you for your comment!
 
    I am not sure if you have appreciated quite how= =20 erratic computer software clocks can be? Let's say that we have three amateu= r=20 stations which know their Lat and Long co-ordinates, but are each only = 50=20 km apart in a roughly straight line in a UK setting. My clock lost = ;6=20 sec per hour and the central station gained 6 sec per hour wh= en=20 checked last week, but the other end one is unknown. We are all us= ing=20 the standard Widows clock update of once per week and are at the end of the=20 cycle. We all measure a P / S delay times of the order of 10 min,=20= but=20 we have only the one vertical sensor with some cross sensitivity.
 
    Sure we can put in figures for the average trav= el=20 times for a range of depths, but estimating a 'cocked hat position' and work= ing=20 back to the time of origin leaves several minutes unexplained.
 
    How do you suggest that we get an estimate of t= he=20 time, location and depth of the quake and the probable errors,=20 please?
 
    Regards,
 
    Chris Chapman
    
Subject: Re: On timing From: John or Jan Lahr JohnJan@........ Date: Mon, 11 Apr 2005 22:21:16 -0600 At 08:03 PM 4/11/2005, you wrote: > How do you suggest that we get an estimate of the time, location and > depth of the quake and the probable errors, please? Hi Chris, I don't advocate poor timing, but because it sometimes happens my HYPOELLIPSE program for locating regional earthquakes in Alaska allowed stations to provide P and S times that would be used only for their S minus P interval. If all of the available stations had only the S minus P interval, then it was still possible to compute the latitude, longitude, depth, and spatial error ellipsoid, but the origin time remained unknown. Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: On timing From: Mike Price mprice@........ Date: Mon, 11 Apr 2005 21:58:18 -0700 Chris, The RTC in a typical PC is a joke. However, if you run clock synchronization SW you can discipline your PC clock to be quite stable and accurate despite the poor performance of the RTC HW. Generally, the HW clock is ignored - only the system clock (in the OS) matters and that is adjusted regularly as its drift with respect to a time standard is monitored. NTP is quite capable of maintaining accurate local time even when the routing path to the server is inconsistent since each server transaction involves multiple exchanges to determine the offset between the local clock and the server. We manage a large number of remote computers synchronized through the Internet using ntp and they maintain clock synchronization to within a few jiffies (jiffy=10mS). Mike ChrisAtUpw@....... wrote: > Dear Dr McCue, > > Thank you for your comment! > > I am not sure if you have appreciated quite how erratic computer > software clocks can be? Let's say that we have three amateur stations > which know their Lat and Long co-ordinates, but are each only 50 km > apart in a roughly straight line in a UK setting. My clock lost 6 sec > per hour and the central station gained 6 sec per hour when checked > last week, but the other end one is unknown. We are all using the > standard Widows clock update of once per week and are at the end of > the cycle. We all measure a P / S delay times of the order of 10 min, > but we have only the one vertical sensor with some cross sensitivity. > > Sure we can put in figures for the average travel times for a > range of depths, but estimating a 'cocked hat position' and working > back to the time of origin leaves several minutes unexplained. > > How do you suggest that we get an estimate of the time, location > and depth of the quake and the probable errors, please? > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Where was it? From: 1goss@........... Date: Thu, 14 Apr 2005 18:49:57 +0000 I got this event very clear! and and it was on Ceri PWLA EHZ NM : Pickwick Lake, AL Helicorder Display. I wrote a letter to CERI asking why it was not ploted on the Recent Earthquakes in Central US. I got a reply and do appreicate they took time to investigate.They are very nice. I would like to know what you all on the list think,does this happen often?? links to my event and the CERI seismograph 30 miles north of me are at the bottom of the page. The prociding is the letter they sent me back. Hi Bryan: You can just barely see this one on our next closest stations, OXF and LRAL. These events can be seen very well on PWLA but not on a sufficient number of other stations to reliably locate it. We only publish reliably located events. It is a bit of an enigma where the events are actually coming from (most likely south of PWLA, or perhaps local and shallow) and why. PWLA is an unusually sensitive stations and records well events not seen by the rest of the network. On Thu, 14 Apr 2005, Bryan Goss wrote: > I did not see this event on the Recent Earthquakes in Central US. > > UTC 4/13/05 14:06:16 > > > This is Ceri PWLA EHZ NM : Pickwick Lake, AL Helicorder Display > http://folkworm.ceri.memphis.edu/heli_nm/PWLA_EHZ_NM.2005041300.gif > > > I saw it on my homebuilt Lehman seismometer > In Corinth MS. as well this is why I ask. > https://home.comcast.net/~bryangoss/micro.jpg I also submitted this on the CERI ask a Ask a Seismologist / Geologist Page . Mitch Center for Earthquake Research and Information (CERI) University of Memphis Ph: 901-678-4940 Memphis, TN 38152 Fax: 901-678-4734 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Where was it? From: John or Jan Lahr JohnJan@........ Date: Thu, 14 Apr 2005 13:39:26 -0600 You might be able to get a rough location by using the S minus P intervals at your station and at PWLA. This will be ambiguous with just two stations, but the weak arrivals at the other stations might eliminate one of the two possible locations. Sooner or later there will probably be a larger event from the same location that is located. John At 12:49 PM 4/14/2005, you wrote: >I got this event very clear! __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Nice to be enjoyed ... I guess From: "RANDY KIMBALL" randy.kimball@........... Date: Thu, 14 Apr 2005 18:32:55 -0500 Hi, By now I'm sure I have been the laughing stock of the whole PSN group. Actually, I've taken it is stride. I've done a good job of screwing up = several posts and wouldn't give up the experience for the world. It has been a humble pie to eat that I deserve intently. Thank you for = each of your patience as I fumble through the learning experience still = thrilled that I can actually see results and plot them on my map from = events on the other side of the world. -randy- (the nerd in Keller, Texas)
Hi,
By now I'm sure I have been the = laughing stock of=20 the whole PSN group.
 
Actually, I've taken it is = stride.  I've done=20 a good job of screwing up several posts and wouldn't give up the = experience for=20 the world.
 
It has been a humble pie to eat = that I deserve=20 intently.  Thank you for each of your patience as I fumble through = the=20 learning experience still thrilled that I can actually see results and = plot them=20 on my map from events on the other side of the world.
 
-randy-  (the nerd in Keller,=20 Texas)
Subject: Re: Nice to be enjoyed ... I guess From: ChrisAtUpw@....... Date: Thu, 14 Apr 2005 22:31:32 EDT In a message dated 15/04/2005, randy.kimball@........... writes: Hi, By now I'm sure I have been the laughing stock of the whole PSN group. Hi Randy, That is nonsense. We try to be co-operative and helpful to new members. Learning a new science like seismology takes quite a lot of hard work and some study. We were mostly new members 10 yours ago! Fortunately there are a hard core of amateurs with semi professional experience about. If you don' t understand, just say so and others will try to help. Regards, Chris Chapman
In a message dated 15/04/2005, randy.kimball@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Hi,
By now I'm sure I have been the laughing=20= stock of=20 the whole PSN group.
Hi Randy,
 
    That is nonsense. We try to be co-operative and= =20 helpful to new members. Learning a new science like seismology takes quite a= lot=20 of hard work and some study. We were mostly new members 10 yours a= go!=20 Fortunately there are a hard core of amateurs with semi professional=20 experience about. If you don' t understand, just say so and others will try=20= to=20 help.
 
    Regards,
 
    Chris Chapman
 
Subject: Re: Nice to be enjoyed ... I guess From: "RANDY KIMBALL" randy.kimball@........... Date: Thu, 14 Apr 2005 22:50:06 -0500 Thanx, Chris, I was being light hearted. I'm having a blast with my sensors, ... I'm = short of time to spend with them ... but the time I get to fool around = and experment is priceless. I have made plenty of mistakes and I'm sure many others have too. The = thing is to enjoy our mistakes, learn from them and realize those that = make no mistakes are either not being honest with themselves or not = pushing the envelope. At this point with my present professional = position and the many other irons I have stuffed into my fire, I am = pushing the envelope to the hilt. To maintain a reality, a good poke at = myself is great medicine. Thank you each again and as soon as I get a = grip on the subject a bit more perhaps I will be smart enough to = articulate some questions. In the mean time I'm having a good time with = a new, for me, technology. This whole process makes me tick. =20 You people should all be very proud. This is a platform from which a = vital learning curve is being nurtured towards learning how to someday = predict seismic events and progressively save more and more lives and = property. This is not a bad thing to be a part of. I hope to = eventually provide a tiny bit of useful input. When I eventually do get = time, I hope to work towards improved instruments, as are and do many of = you. I am very much interested in Z axis. In the mean time my = instruments are set-up as passable at best. A humble bow to all members. ... kudos .... a toast to progress. -randy- ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Thursday, April 14, 2005 9:31 PM Subject: Re: Nice to be enjoyed ... I guess In a message dated 15/04/2005, randy.kimball@........... writes: Hi, By now I'm sure I have been the laughing stock of the whole PSN = group. Hi Randy, That is nonsense. We try to be co-operative and helpful to new = members. Learning a new science like seismology takes quite a lot of = hard work and some study. We were mostly new members 10 yours ago! = Fortunately there are a hard core of amateurs with semi professional = experience about. If you don' t understand, just say so and others will = try to help. Regards, Chris Chapman
Thanx, Chris,
I was being light hearted.  I'm having a blast with my = sensors, ...=20 I'm short of time to spend with them ... but the time I get to fool = around and=20 experment is priceless.
I have made plenty of mistakes and I'm sure many others have = too.  The=20 thing is to enjoy our mistakes, learn from them and realize those that = make no=20 mistakes are either not being honest with themselves or not pushing the=20 envelope.  At this point with my present professional position and = the many=20 other irons I have stuffed into my fire, I am pushing the envelope to = the=20 hilt.  To maintain a reality, a good poke at myself is great=20 medicine.  Thank you each again and as soon as I get a grip on the = subject=20 a bit more perhaps I will be smart enough to articulate some = questions.  In=20 the mean time I'm having a good time with a new, for me, = technology.  This=20 whole process makes me tick. 
You people should all be very proud.  This is a platform from = which a=20 vital learning curve is being nurtured towards learning how to someday = predict=20 seismic events and progressively save more and more lives and = property. =20 This is not a bad thing to be a part of.  I hope to eventually = provide a=20 tiny bit of useful input.  When I eventually do get time, I hope to = work=20 towards improved instruments, as are and do many of you.  I am very = much=20 interested in Z axis.  In the mean time my instruments are set-up = as=20 passable at best.
 
A humble bow to all members. ... kudos .... a toast to = progress.
-randy-
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Thursday, April 14, 2005 = 9:31=20 PM
Subject: Re: Nice to be enjoyed = .... I=20 guess

In a message dated 15/04/2005, randy.kimball@...........=20 writes:
Hi,
By now I'm sure I have been the = laughing stock=20 of the whole PSN group.
Hi Randy,
 
    That is nonsense. We try to be = co-operative and=20 helpful to new members. Learning a new science like seismology takes = quite a=20 lot of hard work and some study. We were mostly new members = 10 yours=20 ago! Fortunately there are a hard core of amateurs with semi = professional=20 experience about. If you don' t understand, just say so and others = will try to=20 help.
 
    Regards,
 
    Chris Chapman
 
Subject: Improvements From: 1goss@........... Date: Fri, 15 Apr 2005 19:18:55 +0000 Chirs Chapman, Thanks for the link to the ball bearings, I have them on the way. I am going to do a total rebuild. I have in hand ½ square aluminium, will this be ok for the boom. If it is not I will buy the ½ nominal stainless steel water pipe you sugested. I also ordered 12*18*¼ inch aluminum plate for the base. If I use a boom length of 30 inches where should I put the weight I will try to attach the support wire the way you sugested as well. It will take me some time but I want the best seismograph I can build. Thanks for all your help it will be used I have printed the emails out to refer to during construction. Bryan S Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Computer Timing Problems / Solutions From: ChrisAtUpw@....... Date: Fri, 15 Apr 2005 21:21:13 EDT Hi there, I have inspected six new computer motherboards. They all appeared to be using the miniature cylindrical 32,768 Hz watch crystals. You can get AT cut crystals in these cases but watch crystals are the commonest. 32 KHz Watch crystals have a parabolic error plot with temperature, peaking at about 25 or 30 C, +/-5 C. The coefficient is ~ 0.04 x (Cdiff)^2 ppm. If it is a 30 C crystal and the temperature falls to 5 C, you can expect to get 25 ppm drift - about 2 sec per day. However, the time loss errors shown on my newish computers are very considerably above this, so I suspect that this must be due to changes / errors in the counted interrupt rate. On older computers the disk drive R/Ws could override the regular interrupt timing. The time update options given in Windows do NOT seem to "discipline" the rate loss of the time system. Some other programs can do this. Most of the USA can receive the WWVB 60 KHz timing signals. The coverage is shown on _http://www.boulder.nist.gov/timefreq/stations/wwvbcoverage.htm_ (http://www.boulder.nist.gov/timefreq/stations/wwvbcoverage.htm) Galleon Systems at _http://www.ntp-time-server.com/_ (http://www.ntp-time-server.com/) produce a range of timing products, from complete time server units to separate module boards. The receivers use a 60 KHz tuned ferrite aerial, costing $2.68. The EM2S receivers cost $10.89. They have a normal operating range of 3 to 12 V DC. They use a crystal filter to get a high stability narrow band response and have an AVC circuit to optimise reception for changes in signal strength. The MCM-RS232 Microcontroller Module costs $15.89. It operates off 3 V DC. When combined with the EM2 Receiver Module and the Antenna, it provides time information in standard RS232 data format via a serial interface. External buffering to full RS232 levels is required using a proprietary RS232 level shifter IC. The advantage of the module compared to direct host decoding of the receiver output is the continuous availability of exact decoded time information with no host processing overhead. The module has a real time clock that recalibrates itself against the Atomic Radio Time Signal. I have used these modules 1,800 miles from the transmitter and they worked reliably. At ranges over about 500 miles, the ferrite aerial should be horizontal, mounted perpendicular to the direction of the transmitter and it can be an advantage to mount the modules high up and external to the building, facing in the direction of the transmitter. I tried a variety of situations to try to make the system fail. Failures were all due to the presence of strong interfering radio signals and not to signal strength / internal noise problems. The decoder modules need about 4 mins of clear signal to synchronise initially, but can update hourly in less than 90 sec. I connected a piezo earpiece to the receiver output and listened for any interfering signals or changes in the output pulse rate. I also measured the voltage on the AVC capacitor, min 0.7 V up to the normal range of 0.9 to 1 V, as a logarithmic indication of the signal strength when selecting reception sites. The receiver + aerial need to be >6 ft away from CRT computer monitors and TV sets. It didn't work well very close to radio and TV transmitters. Steel framed buildings and Al foil / corrugated iron covered roof spaces showed low signal levels. Roof spaces can suffer from very large temperature variations. The radio signal was still received OK, but the presence of utility power wiring allowed the pickup of RFI. Local lightning can prevent clear reception. Local electric arc welding may also give problems. The EM2S receiver would work without problems in poor signal locations where my LW AM radio was seriously effected by internal noise. You can buy (borrow?) battery clocks which give 'Atomic Time' eg Oregon Scientific. These work off the WWVB signal and those with LCD displays have a radiating aerial mast display with four levels indicating the signal strength at the last update. My clock updates every hour. I have no financial or other connection to Galleon Systems. If you look at _http://www.boulder.nist.gov/timefreq/stations/wwvbtimecode.htm_ (http://www.boulder.nist.gov/timefreq/stations/wwvbtimecode.htm) you will see that the 59th and the 1st second of WWVB signal both start with 800 mS low pulses. It should be quite easy to set up a dual retriggerable monostable multivibrator to detect this and to give high precision minute timing and / or second timing pulses. Larry, I would like to suggest that you give consideration to providing the 16-bit Serial Output A/D Board for WinSDR with an option to receive and fully decode WWVB signals, or the ability to read the output of a MCM microcontroller module. I have read your note, dated 1998, on WWVB signal reception. I note that the serial board can currently use WWV minute tone decode signals, but you state that 'You will not get 24 hour reception on any one channel, as long as you can get 4 to 6 hours per day will be fine. At my location I get best reception on 5.0Mhz at night and during the day 10.0Mhz or 15.0Mhz.' Does the timing for SDR originate on the board, or is it dependant on the computer clock, please? My computers can NOT keep time over a timing break of maybe 12 hours, to better than about 2 sec. This is certainly NOT good enough for seismic work! Unlike WWV, WWVB has the potential to provide accurate timing signals over the full 24 hrs for most places in the USA. The extreme range daytime WWVB signal is certainly a lot weaker than the nightime signal, but with the possible exception of Maine, it should be satisfactory The ability to fully decode the WWVB signal could cope with the situation of a power outage. It wasn't until I bought a 60 KHz radio corrected digital clock that I realised just how bad my computer timing systems were! Another reason for doing this is to provide a timing system totally independant of the www. There are already predictions of future communications problems on the web. The total cost could well be about that of just a GPS ANTENNA ! Regards, Chris Chapman
Hi there,
 
    I have inspected six new computer motherboards.= =20 They all appeared to be using the miniature cylindrical 32,768=20 Hz watch crystals. You can get AT cut crystals in these cases=20 but watch crystals are the commonest. 32 KHz Watch crystals have a=20 parabolic error plot with temperature, peaking at about 25 or 30 C, +/-5 C.=20= The=20 coefficient is ~ 0.04 x (Cdiff)^2 ppm. If it is a 30 C crystal and=20 the temperature falls to 5 C, you can expect to get 25 ppm drift - abou= t 2=20 sec per day.     
    However, the time loss errors shown on my=20 newish computers are very considerably above this, so I suspect that this mu= st=20 be due to changes / errors in the counted interrupt rate. On older=20 computers the disk drive R/Ws could override the regular interrupt timing. T= he=20 time update options given in Windows do NOT seem to "discipline" the rate lo= ss=20 of the time system. Some other programs can do this.
 
    Most of the USA can receive the WWVB 60 KHz tim= ing=20 signals. The coverage is shown on http= ://www.boulder.nist.gov/timefreq/stations/wwvbcoverage.htm Galleon=20 Systems at
http://www.ntp-time-server.com/=  =20 produce a range of timing products, from complete time server units to separ= ate=20 module boards.
    The receivers use a 60 KHz tuned ferrite=20 aerial, costing $2.68.
    The EM2S receivers cost $10.89. They have a nor= mal=20 operating range of 3 to 12 V DC. They use a crystal filter to get a high=20 stability narrow band response and have an AVC circuit to optimise=20 reception for changes in signal strength.
    The MCM-RS232 Microcontroller Module costs $15.= 89.=20 It operates off 3 V DC. When combined with the EM2 Receiver Module and the=20 Antenna, it provides time information in standard RS232 data format via a se= rial=20 interface. External buffering to full RS232 levels is required using a=20 proprietary RS232 level shifter IC. The advantage of the module compared to=20 direct host decoding of the receiver output is the continuous availability o= f=20 exact decoded time information with no host processing overhead. The=20 module has a real time clock that recalibrates itself against the Atomi= c=20 Radio Time Signal.
 
    I have used these modules 1,800 miles from= the=20 transmitter and they worked reliably. At ranges over about 500 miles, t= he=20 ferrite aerial should be horizontal, mounted perpendicular to the direction=20= of=20 the transmitter and it can be an advantage to mount the modules high up and=20 external to the building, facing in the direction of the transmitter. I= =20 tried a variety of situations to try to make the system fail. Failures were=20= all=20 due to the presence of strong interfering radio signals and not to signal=20 strength / internal noise problems. The decoder modules need about 4 mi= ns=20 of clear signal to synchronise initially, but can update hourly in less than= 90=20 sec. I connected a piezo earpiece to the receiver output and listened f= or=20 any interfering signals or changes in the output pulse rate. I also measured= the=20 voltage on the AVC capacitor, min 0.7 V up to the normal range of 0.9 to 1 V= , as=20 a logarithmic indication of the signal strength when selecting reception=20 sites.
 
    The receiver + aerial need to be >6 ft away=20= from=20 CRT computer monitors and TV sets. It didn't work well very close to ra= dio=20 and TV transmitters. Steel framed buildings and Al foil / corrugated ir= on=20 covered roof spaces showed low signal levels. Roof spaces can suffer fr= om=20 very large temperature variations. The radio signal was still received OK, b= ut=20 the presence of utility power wiring allowed the pickup of RFI. Local=20 lightning can prevent clear reception. Local electric arc welding may a= lso=20 give problems.
 
    The EM2S receiver would work without problems i= n=20 poor signal locations where my LW AM radio was seriously effected by=20 internal noise. You can buy (borrow?) battery clocks which give=20 'Atomic Time' eg Oregon Scientific. These work off the WWVB signal=20 and those with LCD displays have a radiating aerial mast display with f= our=20 levels indicating the signal strength at the last update. My clock updates e= very=20 hour. I have no financial or other connection to Galleon Systems.
 
    If you look at http= ://www.boulder.nist.gov/timefreq/stations/wwvbtimecode.htm you=20 will see that the 59th and the 1st second of WWVB signal both start with 800= mS=20 low pulses. It should be quite easy to set up a dual retriggerable monostabl= e=20 multivibrator to detect this and to give high precision minute timing and /=20= or=20 second timing pulses.  
 
    Larry, I would like to suggest that you give=20 consideration to providing the 16-bit Serial Output A/D Board for WinSDR wit= h an=20 option to receive and fully decode WWVB signals, or the ability to read the=20 output of a MCM microcontroller module. I have read your note, dated 1998, o= n=20 WWVB signal reception.
    I note that the serial board can currently use=20= WWV=20 minute tone decode signals, but you state that 'You will not get 24 hour=20 reception on any one channel, as long as you can get 4 to 6 hours per day wi= ll=20 be fine. At my location I get best reception on 5.0Mhz at night and during t= he=20 day 10.0Mhz or 15.0Mhz.'
    Does the timing for SDR originate on the board,= or=20 is it dependant on the computer clock, please? My computers can NOT keep tim= e=20 over a timing break of maybe 12 hours, to better than about 2 sec. This is=20 certainly NOT good enough for seismic work! Unlike WWV, WWVB has t= he=20 potential to provide accurate timing signals over the full 24 hrs for most=20 places in the USA. The extreme range daytime WWVB signal is certainly a= lot=20 weaker than the nightime signal, but with the possible exception of Mai= ne,=20 it should be satisfactory
    The ability to fully decode the WWVB signal cou= ld=20 cope with the situation of a power outage. It wasn't until I bought a 60 KHz= =20 radio corrected digital clock that I realised just how bad my computer timin= g=20 systems were! Another reason for doing this is to provide a timing= =20 system totally independant of the www. There are already=20 predictions of future communications problems on the web.
 
    The total cost could well be about that of=20 just a GPS ANTENNA !
    
    Regards,
 
    Chris Chapman
Subject: Re: Improvements From: ChrisAtUpw@....... Date: Fri, 15 Apr 2005 22:17:31 EDT In a message dated 15/04/2005, 1goss@........... writes: Chris Chapman, Thanks for the link to the ball bearings, I have them on the way. I am going to do a total rebuild. I have in hand =BD square aluminium, will= =20 this be ok for the boom. If it is not I will buy the =BD nominal stainless =20= steel=20 water pipe you suggested. Hi Bryan, =20 How flexible is your 1/2" Al? I would rate this as a minimum size. I=20 prefer to 'do things the easy way', if there are no other disadvantages. Be= ing=20 able to buy compression ends for water pipe is an easier than making plug e= nds=20 for a square tube. Before you decide, see what pipe you can easily buy? You= =20 can mount your hard plate on the flat end and drill the other end to hold t= he=20 support plate for the coil. Check whether you can get compression Xs withou= t=20 too much trouble. They are available, but not from every supplier.=20 I also ordered 12*18*=BC inch aluminum plate for the base. If I use a boom length of 30 inches where should I put the weight I will tr= y=20 to attach the support wire the way you suggested as well. It will take me=20 some time but I want the best seismograph I can build. I would mount the weight as far along the boom as possible, just before the= =20 end stop for the sensor. I would put a tongue of damping copper horizontall= y=20 under the boom with a gap of maybe 3/4", space enough to slide a damping=20 fixing over it. The magnets are 1/4" thick and so are the backing plates. =20= The=20 tongue 'faces back' toward the pivot. Did I send you a drawing of the fixtu= re=20 that I use? Cancel this? Alternatively, put your existing damping plate right on the end, using=20 your existing magnets and mount the coil under the arm on the bearing side=20= of=20 the mass. One query - your mass looks as if it is in a tin can? Is this mad= e=20 of steel or Al? If it is steel or has a steel lip, you will have to watch o= ut=20 for interactions with the magnets. =20 ** Before you disassemble everything, I suggest that you drain your oil=20 tray and check that you can get enough damping with your existing magnets,=20 narrowing the gap as necessary. **=20 =20 What thickness is your copper damping plate?=20 I saw one seismometer which used a 3/8" thick horizontal copper plate 5= "=20 x 5" for the mass and put the damping magnets on top and bottom! But I=20 don't know what it cost!=20 =20 There is no 'perfect' way to build a seismometer, but there are=20 constructional / instumentation problems which are best avoided. Knife edge= bearings=20 and oil damping are two of them! =20 Regards, =20 Chris Chapman
In a message dated 15/04/2005, 1goss@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Chris=20 Chapman,

Thanks for the link to the ball bearings, I have them on t= he=20 way.
I am going to do a total rebuild. I have in hand =BD square alumin= ium,=20 will this be ok for the boom. If it is not I will buy the =BD nominal stai= nless=20 steel water pipe you suggested.
Hi Bryan,
 
    How flexible is your 1/2" Al? I would rate this= as=20 a minimum size. I prefer to 'do things the easy way', if there are no other=20 disadvantages. Being able to buy compression ends for water pipe is an easie= r=20 than making plug ends for a square tube. Before you decide, see what pipe yo= u=20 can easily buy? You can mount your hard plate on the flat end and drill the=20 other end to hold the support plate for the coil. Check whether you can= get=20 compression Xs without too much trouble. They are available, but not from ev= ery=20 supplier. 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I also=20 ordered 12*18*=BC inch aluminum plate for the base.
If I use a boom len= gth of=20 30 inches where should I put the weight I will try to attach the support w= ire=20 the way you suggested as well. It will take me some time but I want the be= st=20 seismograph I can build.
    I would mount the weight as far along the boom=20= as=20 possible, just before the end stop for the sensor. I would put a tongue of=20 damping copper horizontally under the boom with a gap of maybe 3/4", space=20 enough to slide a damping fixing over it. The magnets are 1/4" thick and so=20= are=20 the backing plates.  The tongue 'faces back' toward the pivot. Did I se= nd=20 you a drawing of the fixture that I use? Cancel this?
    Alternatively, put your existing damping plate=20 right on the end, using your existing magnets and mount the coil under the a= rm=20 on the bearing side of the mass. One query - your mass looks as if it is in=20= a=20 tin can? Is this made of steel or Al? If it is steel or has a steel lip, you= =20 will have to watch out for interactions with the magnets.
 
**    Before you disassemble everything, I sugge= st=20 that you drain your oil tray and check that you can get enough damping with=20= your=20 existing magnets, narrowing the gap as necessary. **
 
    What thickness is your copper damping=20 plate? 
    I saw one seismometer which used a 3/8" thick=20 horizontal copper plate 5" x 5" for the mass and put the damping=20 magnets on top and bottom!  But I don't know what it cost!
 
    There is no 'perfect' way to build a seismomete= r,=20 but there are constructional / instumentation problems which are best avoide= d.=20 Knife edge bearings and oil damping are two of them!
 
    Regards,
 
    Chris Chapman
Subject: Re: Computer Timing Problems / Solutions From: ian ian@........... Date: Sat, 16 Apr 2005 11:34:51 +0100 Regarding the standard a/d board and without knowing its details, I note that there is a crystal onboard and that the spec of the a/d is 100 samples/second. What would be the accuracy obtained for the time between the P and S wave by simply counting samples between them and multiplying that by the sample period? Would this suffice? The flip side of this question is: if that crystal isn't very good, then is all this for naught!? Thinking more about this board, is the sample data buffered (other than that provided by the uart)? Are samples lost/overwritten if the pc is temporarily busy? Also, after last week's discussion, was the conclusion that the accuracy which can be achieved by a good NTP service sufficient for absolute timing and that the emphasis should be on the relative time between the 2 waves. Again, what is a reasonable spec? Ian Smith ChrisAtUpw@....... wrote: > Hi there, > > I have inspected six new computer motherboards. They all appeared > to be using the miniature cylindrical 32,768 Hz watch crystals. You > can get AT cut crystals in these cases but watch crystals are the > commonest. 32 KHz Watch crystals have a parabolic error plot with > temperature, peaking at about 25 or 30 C, +/-5 C. The coefficient is ~ > 0.04 x (Cdiff)^2 ppm. If it is a 30 C crystal and the temperature > falls to 5 C, you can expect to get 25 ppm drift - about 2 sec per > day. > However, the time loss errors shown on my newish computers are > very considerably above this, so I suspect that this must be due to > changes / errors in the counted interrupt rate. On older computers the > disk drive R/Ws could override the regular interrupt timing. The time > update options given in Windows do NOT seem to "discipline" the rate > loss of the time system. Some other programs can do this. > > Most of the USA can receive the WWVB 60 KHz timing signals. The > coverage is shown on > http://www.boulder.nist.gov/timefreq/stations/wwvbcoverage.htm Galleon > Systems at > http://www.ntp-time-server.com/ produce a range of timing products, > from complete time server units to separate module boards. > The receivers use a 60 KHz tuned ferrite aerial, costing $2.68. > The EM2S receivers cost $10.89. They have a normal operating range > of 3 to 12 V DC. They use a crystal filter to get a high stability > narrow band response and have an AVC circuit to optimise reception for > changes in signal strength. > The MCM-RS232 Microcontroller Module costs $15.89. It operates off > 3 V DC. When combined with the EM2 Receiver Module and the Antenna, it > provides time information in standard RS232 data format via a serial > interface. External buffering to full RS232 levels is required using a > proprietary RS232 level shifter IC. The advantage of the module > compared to direct host decoding of the receiver output is the > continuous availability of exact decoded time information with no host > processing overhead. The module has a real time clock that > recalibrates itself against the Atomic Radio Time Signal. > > I have used these modules 1,800 miles from the transmitter and > they worked reliably. At ranges over about 500 miles, the ferrite > aerial should be horizontal, mounted perpendicular to the direction of > the transmitter and it can be an advantage to mount the modules high > up and external to the building, facing in the direction of the > transmitter. I tried a variety of situations to try to make the system > fail. Failures were all due to the presence of strong interfering > radio signals and not to signal strength / internal noise problems. > The decoder modules need about 4 mins of clear signal to synchronise > initially, but can update hourly in less than 90 sec. I connected a > piezo earpiece to the receiver output and listened for any interfering > signals or changes in the output pulse rate. I also measured the > voltage on the AVC capacitor, min 0.7 V up to the normal range of 0.9 > to 1 V, as a logarithmic indication of the signal strength when > selecting reception sites. > > The receiver + aerial need to be >6 ft away from CRT computer > monitors and TV sets. It didn't work well very close to radio and TV > transmitters. Steel framed buildings and Al foil / corrugated iron > covered roof spaces showed low signal levels. Roof spaces can suffer > from very large temperature variations. The radio signal was still > received OK, but the presence of utility power wiring allowed the > pickup of RFI. Local lightning can prevent clear reception. Local > electric arc welding may also give problems. > > The EM2S receiver would work without problems in poor signal > locations where my LW AM radio was seriously effected by > internal noise. You can buy (borrow?) battery clocks which give > 'Atomic Time' eg Oregon Scientific. These work off the WWVB signal > and those with LCD displays have a radiating aerial mast display with > four levels indicating the signal strength at the last update. My > clock updates every hour. I have no financial or other connection to > Galleon Systems. > > If you look at > http://www.boulder.nist.gov/timefreq/stations/wwvbtimecode.htm you > will see that the 59th and the 1st second of WWVB signal both start > with 800 mS low pulses. It should be quite easy to set up a dual > retriggerable monostable multivibrator to detect this and to give high > precision minute timing and / or second timing pulses. > > Larry, I would like to suggest that you give consideration to > providing the 16-bit Serial Output A/D Board for WinSDR with an option > to receive and fully decode WWVB signals, or the ability to read the > output of a MCM microcontroller module. I have read your note, dated > 1998, on WWVB signal reception. > I note that the serial board can currently use WWV minute tone > decode signals, but you state that 'You will not get 24 hour reception > on any one channel, as long as you can get 4 to 6 hours per day will > be fine. At my location I get best reception on 5.0Mhz at night and > during the day 10.0Mhz or 15.0Mhz.' > Does the timing for SDR originate on the board, or is it dependant > on the computer clock, please? My computers can NOT keep time over a > timing break of maybe 12 hours, to better than about 2 sec. This is > certainly NOT good enough for seismic work! Unlike WWV, WWVB has the > potential to provide accurate timing signals over the full 24 hrs for > most places in the USA. The extreme range daytime WWVB signal is > certainly a lot weaker than the nightime signal, but with the possible > exception of Maine, it should be satisfactory > The ability to fully decode the WWVB signal could cope with the > situation of a power outage. It wasn't until I bought a 60 KHz radio > corrected digital clock that I realised just how bad my computer > timing systems were! Another reason for doing this is to provide a > timing system totally independant of the www. There are already > predictions of future communications problems on the web. > > The total cost could well be about that of just a GPS ANTENNA ! > > Regards, > > Chris Chapman Regarding the standard a/d board and without knowing its details, I note that there is a crystal onboard and that the spec of the a/d is 100 samples/second.  What would be the accuracy obtained for the time between the P and S wave by simply counting samples between them and multiplying that by the sample period?  Would this suffice?  The flip side of this question is: if that crystal isn't very good, then is all this for naught!?

Thinking more about this board, is the sample data buffered (other than that provided by the uart)?  Are samples lost/overwritten if the pc is temporarily busy?

Also, after last week's discussion, was the conclusion that the accuracy which can be achieved by a good NTP service sufficient for absolute timing and that the emphasis should be on the relative time between the 2 waves.  Again, what is a reasonable spec?

Ian Smith

ChrisAtUpw@....... wrote:
Hi there,
 
    I have inspected six new computer motherboards. They all appeared to be using the miniature cylindrical 32,768 Hz watch crystals. You can get AT cut crystals in these cases but watch crystals are the commonest. 32 KHz Watch crystals have a parabolic error plot with temperature, peaking at about 25 or 30 C, +/-5 C. The coefficient is ~ 0.04 x (Cdiff)^2 ppm. If it is a 30 C crystal and the temperature falls to 5 C, you can expect to get 25 ppm drift - about 2 sec per day.     
    However, the time loss errors shown on my newish computers are very considerably above this, so I suspect that this must be due to changes / errors in the counted interrupt rate. On older computers the disk drive R/Ws could override the regular interrupt timing. The time update options given in Windows do NOT seem to "discipline" the rate loss of the time system. Some other programs can do this.
 
    Most of the USA can receive the WWVB 60 KHz timing signals. The coverage is shown on http://www.boulder.nist.gov/timefreq/stations/wwvbcoverage.htm Galleon Systems at
http://www.ntp-time-server.com/  produce a range of timing products, from complete time server units to separate module boards.
    The receivers use a 60 KHz tuned ferrite aerial, costing $2.68.
    The EM2S receivers cost $10.89. They have a normal operating range of 3 to 12 V DC. They use a crystal filter to get a high stability narrow band response and have an AVC circuit to optimise reception for changes in signal strength.
    The MCM-RS232 Microcontroller Module costs $15.89. It operates off 3 V DC. When combined with the EM2 Receiver Module and the Antenna, it provides time information in standard RS232 data format via a serial interface. External buffering to full RS232 levels is required using a proprietary RS232 level shifter IC. The advantage of the module compared to direct host decoding of the receiver output is the continuous availability of exact decoded time information with no host processing overhead. The module has a real time clock that recalibrates itself against the Atomic Radio Time Signal.
 
    I have used these modules 1,800 miles from the transmitter and they worked reliably. At ranges over about 500 miles, the ferrite aerial should be horizontal, mounted perpendicular to the direction of the transmitter and it can be an advantage to mount the modules high up and external to the building, facing in the direction of the transmitter. I tried a variety of situations to try to make the system fail. Failures were all due to the presence of strong interfering radio signals and not to signal strength / internal noise problems. The decoder modules need about 4 mins of clear signal to synchronise initially, but can update hourly in less than 90 sec. I connected a piezo earpiece to the receiver output and listened for any interfering signals or changes in the output pulse rate. I also measured the voltage on the AVC capacitor, min 0.7 V up to the normal range of 0.9 to 1 V, as a logarithmic indication of the signal strength when selecting reception sites.
 
    The receiver + aerial need to be >6 ft away from CRT computer monitors and TV sets. It didn't work well very close to radio and TV transmitters. Steel framed buildings and Al foil / corrugated iron covered roof spaces showed low signal levels. Roof spaces can suffer from very large temperature variations. The radio signal was still received OK, but the presence of utility power wiring allowed the pickup of RFI. Local lightning can prevent clear reception. Local electric arc welding may also give problems.
 
    The EM2S receiver would work without problems in poor signal locations where my LW AM radio was seriously effected by internal noise. You can buy (borrow?) battery clocks which give 'Atomic Time' eg Oregon Scientific. These work off the WWVB signal and those with LCD displays have a radiating aerial mast display with four levels indicating the signal strength at the last update. My clock updates every hour. I have no financial or other connection to Galleon Systems.
 
    If you look at http://www.boulder.nist.gov/timefreq/stations/wwvbtimecode.htm you will see that the 59th and the 1st second of WWVB signal both start with 800 mS low pulses. It should be quite easy to set up a dual retriggerable monostable multivibrator to detect this and to give high precision minute timing and / or second timing pulses.  
 
    Larry, I would like to suggest that you give consideration to providing the 16-bit Serial Output A/D Board for WinSDR with an option to receive and fully decode WWVB signals, or the ability to read the output of a MCM microcontroller module. I have read your note, dated 1998, on WWVB signal reception.
    I note that the serial board can currently use WWV minute tone decode signals, but you state that 'You will not get 24 hour reception on any one channel, as long as you can get 4 to 6 hours per day will be fine. At my location I get best reception on 5.0Mhz at night and during the day 10.0Mhz or 15.0Mhz.'
    Does the timing for SDR originate on the board, or is it dependant on the computer clock, please? My computers can NOT keep time over a timing break of maybe 12 hours, to better than about 2 sec. This is certainly NOT good enough for seismic work! Unlike WWV, WWVB has the potential to provide accurate timing signals over the full 24 hrs for most places in the USA. The extreme range daytime WWVB signal is certainly a lot weaker than the nightime signal, but with the possible exception of Maine, it should be satisfactory
    The ability to fully decode the WWVB signal could cope with the situation of a power outage. It wasn't until I bought a 60 KHz radio corrected digital clock that I realised just how bad my computer timing systems were! Another reason for doing this is to provide a timing system totally independant of the www. There are already predictions of future communications problems on the web.
 
    The total cost could well be about that of just a GPS ANTENNA !
    
    Regards,
 
    Chris Chapman
Subject: Re: Computer Timing Problems / Solutions From: Larry Cochrane lcochrane@.............. Date: Sat, 16 Apr 2005 16:30:32 -0700 Chris, The time stamping of the data is done on the A/D board. If you have a time reference like GPS the time accuracy is one or two milliseconds. The board uses a 1 millisecond interrupt so the timing can't be any better then one ms. With WWV and WWVB the accuracy will be in the order of +-10 to +-20 ms depending on the signal quality. If you have a time reference connected to the A/D board WinSDR can use the A/D board's time to keep the PC's time accurate to +- 250 ms. Since the time stamping is done on the A/D board there is no need to keep the PC's time accurate to less then a few seconds. WinSDR does use the system's time for things like file names so the PC's time should be near the A/D board's time. If there is no timing reference available for the A/D board you can use the PC's time. In this mode the A/D board requests the current time from the PC every minute or so and uses this time for data time stamping. If the PC's time is keep accurate with a program like NTP the overall accuracy can be +- 30 or +-50 ms or about the same as WWV/WWVB. With regard to the different time references. By far GPS is the best, if you can find a location for the antenna that will allow the receiver to see two or more satellite most of the time. The cost of a OEM GPS receiver with a 1 PPS signal is now below $100.00 USD. I am now selling the Garmin GPS 18 (http://www.garmin.com/products/gps18oem/index.jsp) for this price. This is a very nice receiver that works very will with my A/D board. Given that the cost to use GPS keeps going down I not sure I see the need to support WWV/WWVB any more. The other problem is these signals are only available here in the States. Since half of my sales are overseas a lot of people will not be able to use this feature. And with most of the PSN station having a full time Internet connection now a days they always have the option to use NTP etc as a time reference. Regards, Larry Cochrane Redwood City, PSN ChrisAtUpw@....... wrote: > Larry, I would like to suggest that you give consideration to providing > the 16-bit Serial Output A/D Board for WinSDR with an option to receive and > fully decode WWVB signals, or the ability to read the output of a MCM > microcontroller module. I have read your note, dated 1998, on WWVB signal reception. > I note that the serial board can currently use WWV minute tone decode > signals, but you state that 'You will not get 24 hour reception on any one > channel, as long as you can get 4 to 6 hours per day will be fine. At my location > I get best reception on 5.0Mhz at night and during the day 10.0Mhz or > 15.0Mhz.' > Does the timing for SDR originate on the board, or is it dependant on > the computer clock, please? My computers can NOT keep time over a timing break > of maybe 12 hours, to better than about 2 sec. This is certainly NOT good > enough for seismic work! Unlike WWV, WWVB has the potential to provide accurate > timing signals over the full 24 hrs for most places in the USA. The extreme > range daytime WWVB signal is certainly a lot weaker than the nightime signal, > but with the possible exception of Maine, it should be satisfactory > The ability to fully decode the WWVB signal could cope with the > situation of a power outage. It wasn't until I bought a 60 KHz radio corrected > digital clock that I realised just how bad my computer timing systems were! Another > reason for doing this is to provide a timing system totally independant of > the www. There are already predictions of future communications problems on > the web. > > The total cost could well be about that of just a GPS ANTENNA ! __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Computer Timing Problems / Solutions From: Larry Cochrane lcochrane@.............. Date: Sat, 16 Apr 2005 17:21:07 -0700 Ian, Ian wrote: > Regarding the standard a/d board and without knowing its details, I note > that there is a crystal onboard and that the spec of the a/d is 100 > samples/second. What would be the accuracy obtained for the time > between the P and S wave by simply counting samples between them and > multiplying that by the sample period? Would this suffice? The flip > side of this question is: if that crystal isn't very good, then is all > this for naught!? I assume you are taking about my A/D board... I check the frequency of the 4 Mhz oscillator used on my A/D board before I solder it to the board. If it's over/under +-75 Hz I do not use it. With a good timing reference, the A/D board can correct for the oscillator being off frequency by adding or subtracting time to the time accumulator at some time interval. This process compensates for the oscillator running a little higher or lower in frequency. For all of this to work correctly the time reference must be stable. GPS is the best since the 1PPS signal is accurate to a few microseconds. With WWV/WWVB or using the PC's time it's harder for the board to do this correctly since the time reference can jump around a few milliseconds or more. > > Thinking more about this board, is the sample data buffered (other than > that provided by the uart)? Are samples lost/overwritten if the pc is > temporarily busy? The board buffers the data for one second and then sends it out to WinSDR. The packet is also saved in memory so WinSDR can request a retransmission if the data never gets to the PC. The A/D board can save about 30 seconds worth of data that can be resent to the host. > > Also, after last week's discussion, was the conclusion that the accuracy > which can be achieved by a good NTP service sufficient for absolute > timing and that the emphasis should be on the relative time between the > 2 waves. Again, what is a reasonable spec? Here's my .02 cents on this. If you are only going to record teleseismic events, anything under 100 milliseconds is probably an overkill. If you are going to record local events the time should be accurate to within one or two sample periods. If you are running at 100 samples per second this is 10 to 20 ms. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Improvements From: 1goss@........... Date: Sun, 17 Apr 2005 10:36:12 +0000 Hey Chris , "How flexible is your 1/2" Al? I would rate this as a minimum size. I prefer to 'do things the easy way" It is not flexible it is thick tubing, however I like the easy way also so I will try to buy the ½ nominal stainless steel water pipe you suggested. I am having problems finding what I need, But I think it is my lack of understanding. What is compression Xs. I ask the guy at the hardware store, Lowes of Corinth he said they did not carry stainless steel pipe and did not know what compression Xs was. I think I can get the pipe at another suppler here but I need to understand what I am looking for. "Alternatively, put your existing damping plate right on the end, using your existing magnets and mount the coil under the arm on the bearing side of the mass. " I like this Idea It is incorporated in the drawing I link to at the bottom of the page. I need to know how to mount the coil, under the boom? or to the side? I will mount the magnet to the AL plate. "One query - your mass looks as if it is in a tin can?" I melted the lead in a tin can then cut away the can, its now just lead that looks like a can. "What thickness is your copper damping plate?" It is currently 1/16 but 1/8 4x4 will be here this week so it will be 1/8. This is a link to a drawing I did so I could ask a few more questions. https://home.comcast.net/~bryangoss/3d.jpg 1. I think I got the ball baring and tool bit backwards in the drawing. Would this matter if I built it that way? 2.How critical is the angel of the wire? The drawing it is to scale the black pipe frame is 22 inches tall and the boom 30 inches long. 3.There is a red square about where I think the coil should go will this be ok. 4.Does the support wire attachment to the weight look like it should? like the drawing you sent me. 5. I found stainless screws. What kind of glue did you use to attach the nuts to the bottom of the AL plate? They are small Machine Screws 8-32 x 2 ss. 6.Note the flat plate, would this be better so I could adjust the position of the ball baring or flat with a bolt . The pipe union I have is not adjustable. Its late for me I hope this all makes sense Thanks for your help Bryan __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Improvements Implemented.... From: 1goss@........... Date: Sun, 24 Apr 2005 11:34:59 +0000 I now have part of Chris’s improvements to my Lehman Seismometer implemented. I have the ball bearing installed on the pipe union, and carbide bit on the boom. I extended the boom to 36 inches and got the5lb weight to 27 inches out. I did not put the coil on the boom...I left the magnet on the boom and coil on the base plate. I removed the oil dampener and added a new 1/8 copper plate, thicker than what I had , hopefully the magnets are adjusted correctly for the dampener. The Lehman now has a period of 21sec what a difference the ball bearings make!!!! I am going to build a second Lehman and I will put the coil on the boom on that one. Thanks Chris and everyone that has helped Bryan S Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Computer Timing Problems / Solutions From: ChrisAtUpw@....... Date: Wed, 27 Apr 2005 22:24:37 EDT In a message dated 17/04/2005, lcochrane@.............. writes: If there is no timing reference available for the A/D board you can use the PC's time. In this mode the A/D board requests the current time from the PC every minute or so and uses this time for data time stamping. If the PC's time is keep accurate with a program like NTP the overall accuracy can be +- 30 or +-50 ms or about the same as WWV/WWVB. With regard to the different time references. By far GPS is the best, if you can find a location for the antenna that will allow the receiver to see two or more satellite most of the time. The cost of an OEM GPS receiver with a 1 PPS signal is now below $100.00 USD. I am now selling the Garmin GPS 18 (http://www.garmin.com/products/gps18oem/index.jsp) for this price. This is a very nice receiver that works very will with my A/D board. Hi Larry, However, GPS is still the most expensive of the timing options at $140 + carriage. You need a clear path to the satellites and the power requirements of 100 to 185 mA are very high for battery / remote operation. Given that the cost to use GPS keeps going down I not sure I see the need to support WWV/WWVB any more. The other problem is these signals are only available here in the States. Since half of my sales are overseas a lot of people will not be able to use this feature. May I ask that you reconsider the situation, please? You seem to have overlooked the fact that the inexpensive WWVB type modules are available for not only the USA, much of Canada and central America, but also for Europe and Japan. Since the computer modules give a fully decoded time signal, it should be easy to make your board timing automatically fail safe for power outages and for automatic start up. The power requirements ARE designed for battery operation. Your WWV tone decoder timing is only widely available on one frequency during the day and on another during the night and only in North America / eastern Pacific. It is not a 'fit and forget' 24 hour timing solution, unlike many WWVB type systems. Commercial seismic software DOES often use VLF radio signals as alternatives to GPS and on-line timing. >> And with most of the PSN station having a full time Internet connection nowadays they always have the option to use NTP etc as a time reference. Not everyone CAN obtain a permanent network connection and from my experience, you DO NEED to have access to a time set program which MODIFIES (disciplines) your computer clock rate. A permanent line connection is an expense which your customers do not need to have. I cannot obtain a second phone line, even if I wished to pay the extra $290 / year line rental. See _http://www.ntp-time-server.com/_ (http://www.ntp-time-server.com/) and _http://www.galleon.eu.com/_ (http://www.galleon.eu.com/) for radio modules. Regards, Chris Chapman
In a message dated 17/04/2005, lcochrane@.............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If there=20 is no timing reference available for the A/D board you can use the PC's=20
time. In this mode the A/D board requests the current time from the PC= =20 every minute or so and uses this time for data time stamping. If the PC's=20= time=20 is keep accurate with a program like NTP the overall accuracy can be +- 30= or=20 +-50 ms or about the same as WWV/WWVB.

With regard to the different= =20 time references. By far GPS is the best, if you can find
a location fo= r=20 the antenna that will allow the receiver to see two or more satellite most= of=20 the time. The cost of an OEM GPS receiver with a 1 PPS signal is now below= =20 $100.00 USD. I am now selling the Garmin GPS 18=20
(http://www.garmin.com/products/gps18oem/index.jsp) for this price. Th= is=20 is a very
nice receiver that works very will with my A/D board.=20
Hi Larry,
 
    However, GPS is still the most expensive of the= =20 timing options at $140 + carriage. You need a clear path to the satellites a= nd=20 the power requirements of 100 to 185 mA are very high for battery=20= /=20 remote operation.  
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>    Given that the cost to use GPS keeps goin= g down=20 I not sure I see the need to support WWV/WWVB any more. The other problem=20= is=20 these signals are only available here in the States. Since half of my sale= s=20 are overseas a lot of people will not be able to use this feature.=20
    May I ask that you reconsider the situation,=20 please? You seem to have overlooked the fact that the inexpensive WWVB type=20 modules are available for not only the USA, much of=20 Canada and central America, but also=20= for=20 Europe and Japan. Since the compu= ter=20 modules give a fully decoded time signal, it should be easy to make y= our=20 board timing automatically fail safe for power outages and for automatic sta= rt=20 up. The power requirements ARE designed for battery operation.
    Your WWV tone decoder timing is only widely=20 available on one frequency during the day and on another during the nig= ht=20 and only in North America / eastern Pacific. It is not a 'fit and forget' 24= =20 hour timing solution, unlike many WWVB type systems. 
    Commercial seismic software DOES often use V= LF=20 radio signals as alternatives to GPS and on-line timing.
 
>>    And with most of the PSN st= ation=20 having a full time Internet connection nowadays they always have the option=20= to=20 use NTP etc as a time reference.
 
    Not everyone CAN obtain a permanent network=20 connection and from my experience, you DO NEED to have access to a time= set=20 program which MODIFIES (disciplines) your computer clock rate. A permanent l= ine=20 connection is an expense which your customers do not need to have. I cannot=20 obtain a second phone line, even if I wished to pay the extra $290 / year li= ne=20 rental.

 
    See http://www.ntp-time-server.com/=  and=20 http://www.galleon.eu.com/ f= or=20 radio modules.
 
    Regards,
 
    Chris Chapman
Subject: Re: Computer Timing Problems / Solutions From: Mark Robinson mark.robinson@............... Date: Sat, 30 Apr 2005 05:29:58 +1200 Luis Cupido is developing a new version of his Reflock board which some may find of interest as a possible part of a solution to this problem. It could be used to sync the computer's RTC oscillator, or even the instruction clock, to your favourite external reference. Lius' announcement follows, and earlier correspondence about the Reflock can be found in the microwave list archives which you can browse if you sign up at the address below. I'm not proselytising for this thing, just tossing another idea into the pot. regards Mark Luis Cupido wrote: > Hello, > > The result of a joint effort with Steve N7HPR, the Reflock II is > now a reality. > It uses the latest CPLD available from Altera the MAX II that > has room for better locking schemes and more features. > (worth mention that this device can now hold circuits 100x more > complex than a traditional National or Motorola PLL chip). > The first prototype just saw the light recently and can be seen > at my web pages. > > The major top specs are the higher frequency of operation > well above 200MHz direct to the CPLD (actual maximum depends > on what circuit it is configured to) and the on board prescaler > going to 1GHz. Plus the ability to communicate with a small > processor (PIC, Atmel, etc...) to allow loop quality analysis > long term stability log (for 1pps) changing configuration on the fly > etc, etc... > > I do expect that TAPR soon have Kits PCB parts etc, for the people > but I don't really know what are the plans. > > Take a look: > http://w3ref.cfn.ist.utl.pt/cupido/reflock.html > > Thanks > > Luis Cupido. > CT1DMK > > P.S. Please place any question cc to the list and I'll reply > also here so that I do not have to reply the same thing > many times. Thanks. > _______________________________________________ > Microwave mailing list > microwave@................. > http://www.valinet.com/mailman/listinfo/microwave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Improvements and Event !! From: 1goss@........... Date: Mon, 02 May 2005 01:17:42 +0000 Thanks to all for your input. Here are some pictures of the improvements made and the result. 1. Chris’s improvements to my Lehman Seismometer The L bracket for support. https://home.comcast.net/~bryangoss/l2.jpg 2.This is also Chris’s suggestion, however only one ball bearing did not work as well, as I wanted. I got a lot of vertical oscillation. I used 2 ball bearings, and it made a big improvement!!!!! https://home.comcast.net/~bryangoss/dual.jpg Thanks Chris.. 3.This was something I had seen in pictures on the net probably PSN seismographs. It is an aluminum rod, very small in diameter, used in place of wire (except for at each end). This also helped stop vertical oscillations. https://home.comcast.net/~bryangoss/ALrod.jpg 4. This was an improvement as a suggestion from several PSN list members. You said I needed heat, so I put a heat pad on top of the box. This was a 100% fix. I do not get the drifting noise I had. Thanks.. https://home.comcast.net/~bryangoss/heatpad.jpg THE RESULT!!!!!!!!!!!! This was a 4.1 event Manila, AR Sunday, May 1, 2005 at 12:37:32 (UTC) Look at this this, it makes it worth all the work. I just finished up about 3 am the day before. https://home.comcast.net/~bryangoss/LocalEvent.jpg file: https://home.comcast.net/~bryangoss/050501.123700.ch1.psn __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Improvements and Event !! From: Angel sismos@.............. Date: Sun, 1 May 2005 20:47:07 -0500 Bryan, Well hurray for you!! Your email made my day. What a nice seismogram and what great work. Makes me want to build something. Thanks for sharing your working with us. Warmly, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Improvements and Event !! From: "Steve Hammond" shammon1@............. Date: Mon, 2 May 2005 00:02:38 -0700 Data looks great. Regards, Steve Hammond PSN San Jose Aptos, CA -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of 1goss@........... Sent: Sunday, May 01, 2005 6:18 PM To: psn-l@.............. Cc: bryangoss@........... Subject: Improvements and Event !! Thanks to all for your input. Here are some pictures of the improvements made and the result. 1. Chris’s improvements to my Lehman Seismometer The L bracket for support. https://home.comcast.net/~bryangoss/l2.jpg 2.This is also Chris’s suggestion, however only one ball bearing did not work as well, as I wanted. I got a lot of vertical oscillation. I used 2 ball bearings, and it made a big improvement!!!!! https://home.comcast.net/~bryangoss/dual.jpg Thanks Chris.. 3.This was something I had seen in pictures on the net probably PSN seismographs. It is an aluminum rod, very small in diameter, used in place of wire (except for at each end). This also helped stop vertical oscillations. https://home.comcast.net/~bryangoss/ALrod.jpg 4. This was an improvement as a suggestion from several PSN list members. You said I needed heat, so I put a heat pad on top of the box. This was a 100% fix. I do not get the drifting noise I had. Thanks.. https://home.comcast.net/~bryangoss/heatpad.jpg THE RESULT!!!!!!!!!!!! This was a 4.1 event Manila, AR Sunday, May 1, 2005 at 12:37:32 (UTC) Look at this this, it makes it worth all the work. I just finished up about 3 am the day before. https://home.comcast.net/~bryangoss/LocalEvent.jpg file: https://home.comcast.net/~bryangoss/050501.123700.ch1.psn __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Canadian Network From: "Edward Ianni" edwianni1@........... Date: Mon, 02 May 2005 16:11:22 -0400 Some NEWS for the gang that could be be useful. I sometimes use this = Canadian site for "HOURLY PLOTS",....... incidently my homemade "1-sec = Jim Lehman Vertical" correlates to this site very closely (I live in = NJ). Thanks, Ed. http://www.seismo.nrcan.gc.ca/cgi-bin/hplot_e.html
Some NEWS for the gang that could = be be=20 useful. I sometimes use this Canadian site for "HOURLY PLOTS",....... = incidently=20 my homemade "1-sec Jim Lehman Vertical" correlates to this site very = closely (I=20 live in NJ). Thanks,  Ed.
 
http://www.se= ismo.nrcan.gc.ca/cgi-bin/hplot_e.html
Subject: Canadian Network From: "Edward Ianni" edwianni1@........... Date: Mon, 02 May 2005 17:03:02 -0400 In the previous message that I sent to PSN the address at the bottom = of the message for the Canadian link had an =3D inserted into it . I = don't know if this is some sort of protection or something else, = regardless, the =3D must be removed and the rest of the address added in = a normal contiguous manner.
In the previous message that I sent to PSN the = address at=20 the bottom of the message for the Canadian link had an  =3D = inserted into=20 it . I don't know if this is some sort of protection or something = else,=20 regardless, the =3D must be removed and the rest of the address added = in a=20 normal contiguous = manner.
Subject: Re: Canadian Network From: ChrisAtUpw@....... Date: Mon, 2 May 2005 17:42:57 EDT In a message dated 02/05/2005 22:03:31 GMT Daylight Time, edwianni1@........... writes: In the previous message that I sent to PSN the address at the bottom of the message for the Canadian link had an = inserted into it . I don't know if this is some sort of protection or something else, regardless, the = must be removed and the rest of the address added in a normal contiguous manner. Hi there, The Website reference that I received was correct and worked fine (no =). Regards, Chris Chapman
In a message dated 02/05/2005 22:03:31 GMT Daylight Time,=20 edwianni1@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
In the previous message that I sent to PSN the add= ress at=20 the bottom of the message for the Canadian link had an  =3D inserte= d into=20 it . I don't know if this is some sort of protection or something else,=20 regardless, the =3D must be removed and the rest of the address added in= a=20 normal contiguous manner.
Hi there,
 
    The Website reference that I received was corre= ct=20 and worked fine (no =3D).
 
    Regards,
 
    Chris Chapman
Subject: Re: Canadian Network From: "Edward Ianni" edwianni1@........... Date: Tue, 03 May 2005 06:12:58 -0400 =20 One very good example of using this network is the Arkansas Event which = occurred a few days ago. Set the display parameters at the site for 2005 = May 1 12:37:32 UTC=20 http://www.seismo.nrcan.gc.ca/cgi-bin/hplot_e.html ..
         =20
One very good example of using this network is the Arkansas Event = which=20 occurred a few days ago. Set the display parameters at the site = for 2005 May 1 12:37:32 UTC=20
 
http://www.seismo.nrcan.gc.ca/cgi-bin/hplot_e.html.
Subject: Time From: 1goss@........... Date: Fri, 06 May 2005 09:11:35 +0000 I am using one of Larry Cochrane,s 16-Bit Serial Output A/D Board and WinSDR with a garmin gps. How accurate is the timing? CERI ask me they are interested in some off my local data to locate very small events close to me. Also could someone please send me a screen shot of their WinSDR during a quite time set to four lines at 4 minutes each line default setting. Thanks Bryan S Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Time From: Larry Cochrane lcochrane@.............. Date: Fri, 06 May 2005 15:12:39 -0700 Bryan, With the Garmin GPS receiver your timing should be accurate to within one or two milliseconds. Regards, Larry Cochrane Redwood City, PSN 1goss@........... wrote: > I am using one of Larry Cochrane,s 16-Bit Serial Output A/D Board and WinSDR > with a garmin gps. How accurate is the timing? CERI ask me they are interested in some off my local data to locate very small events close to me. > > > Also could someone please send me a screen shot of their WinSDR during a quite time set to four lines at 4 minutes each line default setting. > > Thanks Bryan S Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Time From: ChrisAtUpw@....... Date: Fri, 6 May 2005 19:23:09 EDT In a message dated 06/05/2005, lcochrane@.............. writes: Bryan, With the Garmin GPS receiver your timing should be accurate to within one or two milliseconds. Regards, Larry Cochrane Hi Larry, Do you have any figures, or preferably measurements, for the time delay produced by the filters on your amplifier boards, please? Putting in the values for an 8th order 5 Hz Butterworth low pass filter suggest that the delay is likely to be ~160 milli sec below 2 Hz, peaking to about 280 milli sec at 5 Hz. These delays, while swamping any timing errors, are unlikely to give significant errors in general Earthquake location. However, since an 8 pole 1.5 Hz filter can produce a lag of over 1/2 second, we may sometimes need to take filter delays into account, more particularly for local events. Regards, Chris Chapman
In a message dated 06/05/2005, lcochrane@.............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Bryan,
With the Garmin GPS receiver your timing should be accu= rate=20 to within one or two
milliseconds.
Regards,
Larry=20 Cochrane
Hi Larry,
 
    Do you have any figures, or preferably=20 measurements, for the time delay produced by the filters on your amplifier=20 boards, please?
    
    Putting in the values for an 8th order 5 H= z=20 Butterworth low pass filter suggest that the delay is likely to be ~160= =20 milli sec below 2 Hz, peaking to about 280 milli sec at 5 Hz.
 
    These delays, while swamping any timing errors,= are=20 unlikely to give significant errors in general Earthquake location. However,= =20 since an 8 pole 1.5 Hz filter can produce a lag of over 1/2 second, we may=20 sometimes need to take filter delays into account, more particularly for loc= al=20 events.
 
    Regards,
 
    Chris Chapman
Subject: Re: Time From: Mauro Mariotti mariotti@......... Date: Sat, 07 May 2005 09:20:15 +0200 Hello, this brings the need to apply to the recorded signal a convolution algorythm in order to retrieve the exact ground motion that will correct the waveform also in the time domain and will put down to zero the filter delay at various frequency. Winquake should have the possibility to insert (or better to pick from the file) at least these parameters: (Example for velocity sensors) - Sensor damped sensitivity - Resonance frequency of the sensor - Filter corner frequency - Filter type - Number of Filter poles If a convolution is made over the waveform the original ground motion can be reconstrcuted. This would be a great improvement of an already good software as WinQuake is. regards mauro At 01:23 07/05/2005, you wrote: >In a message dated 06/05/2005, lcochrane@.............. writes: >Bryan, >With the Garmin GPS receiver your timing should be accurate to within one >or two >milliseconds. >Regards, >Larry Cochrane > >Hi Larry, > > Do you have any figures, or preferably measurements, for the time > delay produced by the filters on your amplifier boards, please? > > Putting in the values for an 8th order 5 Hz Butterworth low pass > filter suggest that the delay is likely to be ~160 milli sec below 2 Hz, > peaking to about 280 milli sec at 5 Hz. > > These delays, while swamping any timing errors, are unlikely to give > significant errors in general Earthquake location. However, since an 8 > pole 1.5 Hz filter can produce a lag of over 1/2 second, we may sometimes > need to take filter delays into account, more particularly for local events. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Time From: John or Jan Lahr JohnJan@........ Date: Sat, 07 May 2005 10:25:52 -0600 Hi Brian, I think that the "proof" of the timing system would be to record some time marks right along side your seismometer. This could be set up with a summing amplifier so that the time mark amplitude could be adjusted to a low but visible level. Of course the time marks must be from a very accurate source, such as a GPS receiver. The second marks could be used, as long as you are confident that the system clock is not off by more than 0.5 seconds. Cheers, John At 03:11 AM 5/6/2005, you wrote: >I am using one of Larry Cochrane,s 16-Bit Serial Output A/D Board and WinSDR >with a garmin gps. How accurate is the timing? CERI ask me they are >interested in some off my local data to locate very small events close to me. > > >Also could someone please send me a screen shot of their WinSDR during a >quite time set to four lines at 4 minutes each line default setting. > >Thanks Bryan S Goss > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Time From: Larry Cochrane lcochrane@.............. Date: Sat, 07 May 2005 18:28:04 -0700 Hi Chris, > Hi Larry, > > Do you have any figures, or preferably measurements, for the time > delay produced by the filters on your amplifier boards, please? I measured this a long time ago. The delay is about 30 to 50 ms depending on the cut-off frequency. I did the measurement by feeding in a square-wave and looking at the output with a o-scope. > > Putting in the values for an 8th order 5 Hz Butterworth low pass > filter suggest that the delay is likely to be ~160 milli sec below 2 Hz, > peaking to about 280 milli sec at 5 Hz. > > These delays, while swamping any timing errors, are unlikely to give > significant errors in general Earthquake location. However, since an 8 > pole 1.5 Hz filter can produce a lag of over 1/2 second, we may > sometimes need to take filter delays into account, more particularly for > local events. I ran into this problem when I was first setting up my system. I was using my telemetry demodulator board to record data from one of the USGS sensor sites. I noticed that there was a constant ~200 ms offset from the data I recorded and the data the USGS recorded for the same sensor. It turned out to be the two 8-pole switch capacitor filters I was using on the demodulator board. Each chip was delaying the data by about 100 ms. I did two things to correct for the delay. One was to remove one of the filter chips since there was no need for a 16 pole filter, and the other thing I did was add a delay parameter to SDR. The delay number in milliseconds was subtracted from the event file start time when the program saved an event file. Doing these two things corrected the problem. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filter Time delay From: ChrisAtUpw@....... Date: Sun, 8 May 2005 13:57:51 EDT In a message dated 08/05/2005, lcochrane@.............. writes: Hi Chris, > Hi Larry, > Do you have any figures, or preferably measurements, for the time > delay produced by the filters on your amplifier boards, please? I measured this a long time ago. The delay is about 30 to 50 ms depending on the cut-off frequency. I did the measurement by feeding in a square-wave and looking at the output with a o-scope. > Putting in the values for an 8th order 5 Hz Butterworth low pass > filter suggest that the delay is likely to be ~160 milli sec below 2 Hz, > peaking to about 280 milli sec at 5 Hz. Hi Larry, The calculated figure for your old board, which used a 10 Hz 6 pole Butterworth filter, is a bit over 50 milli sec, which agrees with your old measurements. However, your current boards for a Lehman use a 5 Hz 8 pole Butterworth filter. Reducing the frequency to 5 Hz and adding a couple of stages pushes up the calculated value to ~160 milli sec as above. The calculated value for the 10 Hz 8 pole geophone amplifier is ~75 milli sec. Is there any chance of getting approximate measurements for your current boards, please? 0.16 sec is an appreciable correction. Have you considered using Bessel filters, which give a flat response with no transient impulse peaking? Regards, Chris Chapman
 =20
In a message dated 08/05/2005, lcochrane@.............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000>Hi=20 Chris,

> Hi Larry,
>     Do you have any=20 figures, or preferably measurements, for the time
> delay produced=20= by=20 the filters on your amplifier boards, please?

I measured this a lon= g=20 time ago. The delay is about 30 to 50 ms depending on the
cut-off=20 frequency. I did the measurement by feeding in a square-wave and looking a= t=20
the output with a o-scope.
  
>    = =20 Putting in the values for an 8th order 5 Hz Butterworth low pass
>=20 filter suggest that the delay is likely to be ~160 milli sec below 2 Hz,=20
> peaking to about 280 milli sec at 5 Hz.
Hi Larry,
 
    The calculated figure for your old board, which= =20 used a 10 Hz 6 pole Butterworth filter, is a bit ove= r 50=20 milli sec, which agrees with your old measurements.
 
    However, your current boards for a Le= hman=20 use a 5 Hz 8 pole Butterworth filter. Reducing the=20 frequency to 5 Hz and adding a couple of stages pushes up the calculate= d=20 value to ~160 milli sec as above.
 
    The calculated value for the 10 Hz 8 pole geoph= one=20 amplifier is ~75 milli sec.
 
    Is there any chance of getting approximate=20 measurements for your current boards, please? 0.16 sec is an appreciabl= e=20 correction.
    Have you considered using Bessel filters, which= =20 give a flat response with no transient impulse peaking? 
 
    Regards,
 
    Chris=20 Chapman 
Subject: Time/Filtering From: 1goss@........... Date: Sun, 08 May 2005 23:22:10 +0000 Ok so what should I tell CERI I am getting a lot of different numbers from the replies? Would I be ok to say with filtering I should be within +/- 50ms also will this be good enough to accurately locate a local events with 3 stations less than 50 miles apart. This will explain why I ask is a clip from a letter from Mitch. > > Hi Bryan: > > > > You can just barely see this one on our next closest stations, OXF and > > LRAL. > > These events can be seen very well on PWLA but not on a sufficient number > > of > > other stations to reliably locate it. We only publish reliably located > > events. > > It is a bit of an enigma where the events are actually coming from (most > > likely south of PWLA, or perhaps local and shallow) and why. PWLA is an > > unusually > > sensitive stations and records well events not seen by the rest of the > > network. Mitch > > > > Center for Earthquake Research and Information (CERI) I talked with Mitch on the phone and he just ask me how accurate my timing was, And he may be interested in using it. I was trying to get access to live data from Pickwick He also said he would send me an executable to do that but it would have a five minute delay. He was very helpful to me and I thought it would be great to be able to contribute to their network…. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Time/Filtering From: John or Jan Lahr JohnJan@........ Date: Sun, 08 May 2005 18:22:32 -0600 Picking uncertainty is often in the range of 100 ms, even though the phases= =20 times are recorded to the nearest 10 ms. If your clock error 50 ms or less, your data should be quite useable for locating these events. Also, CERI=20 could use just the S minus P time at your station, combined with P (and if possible S) times at= =20 the other two stations. Of course this will only help if the S is clear and can be=20 picked. Cheers, John At 05:22 PM 5/8/2005, you wrote: >Ok so what should I tell CERI I am getting a lot of different numbers=20 >from the replies? Would I be ok to say with filtering I should be within=20 >+/- 50ms also will this be good enough to accurately locate a local events= =20 >with 3 stations less than 50 miles apart. This will explain why I ask is a= =20 >clip from a letter from Mitch. > > > > Hi Bryan: > > > > > > You can just barely see this one on our next closest stations, OXF and > > > LRAL. > > > These events can be seen very well on PWLA but not on a sufficient= number > > > of > > > other stations to reliably locate it. We only publish reliably= located > > > events. > > > It is a bit of an enigma where the events are actually coming from= (most > > > likely south of PWLA, or perhaps local and shallow) and why. PWLA is= an > > > unusually > > > sensitive stations and records well events not seen by the rest of the > > > network. >Mitch > > > > > > Center for Earthquake Research and Information (CERI) > > >I talked with Mitch on the phone and he just ask me how accurate my timing= =20 >was, >And he may be interested in using it. I was trying to get access to live=20 >data from Pickwick He also said he would send me an executable to do that= =20 >but it would have a five minute delay. He was very helpful to me and I=20 >thought it would be great to be able to contribute to their network=85. > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: My new tiltmeter detected it's first quake From: George Bush ke6pxp@....... Date: Mon, 09 May 2005 22:10:42 -0700 I am in the last stages of completing a new instrument here at Sea Ranch, CA, and a nice quake came along and I was able to see it on the tiltmeter! The quake was: M4.4 64km from Sea Ranch, CA USA, 5 km ( 3 mi) ESE of The Geysers, CA and the PSN server tiltmeter files are: 050509.223742.srt.psn left This actually shows the P and S arrivals, but the quality is terrible as the quake sloshes the mercury and this is a high-Q oscillation. Oh well, I built it to detect Earth tides primarily and any quake detection is just icing on the cake. and 050509.223011.longsrt.psn leftThis is a longer time plot of the above and I am not certain, but it looks like the ground maybe changed tilt when the quake arrived??? If this project is of interest to you, go to my website at http://ntweb.mcn.org/gbush and click on The "Tiltmeter Project" and you can see my writeup and pictures on the construction of the instrument. George Bush Sea Ranch, CA, USA 38.73775N, 123.48882W Subject: Re: Time/Filtering From: Larry Cochrane lcochrane@.............. Date: Tue, 10 May 2005 23:43:48 -0700 Hi Bryan, If your A/D board was locked to GPS time your timing accuracy is closer to +-5ms. The filter delay is more or less constant and can be factor out by placing the filter delay time in WinSDR. In the Channel Settings dialog box you will see a "Filter Delay" edit box. For now use 50 ms. When I get some time I will measure the delay of one of my Amp/Filter board channels and place this information on my Web site. Besides accurate timing you should also have an accurate location of you station. I noticed that the PSN files you placed on your web site did not have the Latitude and Longitude data filled out or the file only had the location too two decimal places. Since you have a GPS receiver you can use it to locate you station's location to a few meters. If you run the current beta version of WinSDR you can use it to average the position information from the GPS receiver connected to the A/D board. See http://www.seismicnet.com/winsdr/betarelease.html for more information. If you let WinSDR average the data for a day or two you will have a very accurate latitude and longitude number. Regards, Larry Cochrane Bryan wrote: > Ok so what should I tell CERI I am getting a lot of different numbers from the replies? Would I be ok >to say with filtering I should be within +/- 50ms also will this be good enough to accurately locate >a local events with 3 stations less than 50 miles apart. This will explain why I ask is a clip >from a letter from Mitch. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: WinQuake settings From: 1goss@........... Date: Wed, 11 May 2005 08:14:51 +0000 How do I get WinQuake to retain settings such as location, lat lon, ect... Also thanks for the replys on timing. Bryan S Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: WinQuake settings From: Larry Cochrane lcochrane@.............. Date: Wed, 11 May 2005 02:53:49 -0700 Hi Bryan, This should probably taken off-line... This information is normally entered in the datalogging program, in your case WinSDR. WinQuake can be used to modify this information if needed. See the WinSDR and WinQuake documentation for more information. Regards, Larry Cochrane Redwood City, PSN 1goss@........... wrote: > How do I get WinQuake to retain settings such as location, lat lon, ect... > Also thanks for the replys on timing. > Bryan S Goss > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My new tiltmeter detected it's first quake From: Angel sismos@.............. Date: Wed, 11 May 2005 05:28:42 -0500 George, Great Work! I'm impressed, make me want to go build something! I want to make one of those 100 meters long and bury it 100 meters down. Quite something to build don't you think. ;-) Well back to reality, I do what to build something soon. regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: New sensor from Freescale Semiconductor From: pgschmidt@............... Date: Fri, 13 May 2005 08:45:09 +0930 G'day All I'm sorry I don't contribute much at all to the group, however this new product was emailed to me and I thought it might come in handy with some sensors/projects going on out there. The email was from Freescale semiconductor and the new product is detailed as follows on their website "The first single-chip, triple-axis accelerometer of its kind." For more info see the website http://www.freescale.com/files/abstract/update/MMA7260QLP.html?tid=tsv Or search for MMA7260QLP at the Freescale website which is http://www.freescale.com Hope it is of some interest. Phil Schmidt Adelaide South Australia __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My new tiltmeter detected it's first quake From: George Bush ke6pxp@....... Date: Fri, 13 May 2005 19:45:24 -0700 Angel- Thank you for the kind words, it has been an adventure to get the tiltmeter working. And I have been impressed with the seismic work you have been doing also! At 05:28 AM 5/11/05 -0500, you wrote: >George, > >Great Work! I'm impressed, make me want to go build something! I >want to make one of those 100 meters long and bury it 100 meters down. >Quite something to build don't you think. ;-) > >Well back to reality, I do what to build something soon. > >regards, > >Angel > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > George __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: BOB BARNS royb1@........... Date: Sat, 14 May 2005 10:27:29 -0400 Hi gang, Teledyne Geotech Portacorder RV-320 Seismograph Item number: 7515956519 Starting price $249 No picture. I don't know what this is. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Doug Crice" dcrice@............ Date: Sat, 14 May 2005 20:52:12 -0700 If this guy wants to start the bidding at $250, he should have a = picture. However, I believe that the Portacorder is a portable recording = seismograph. If memory serves, it came with a small drum recorder, pen, amplifiers = and some sort of timing device, all in an aluminum suitcase. It was used for chasing microearthquakes, aftershocks, and erupting volcanoes. The seismometer was external and no doubt is not included. It's a very nice little package, but of course precedes the age of digital recording. Kinemetrics and Sprengnether had similar products. It was a good = business, because customers needed a dozen or so to surround these little events. Anybody interested in bidding should verify this information. Doug Crice =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of BOB BARNS Sent: Saturday, May 14, 2005 7:27 AM To: psn mail Subject: ebay auction Hi gang, Teledyne Geotech Portacorder RV-320 Seismograph Item number:=20 7515956519 Starting price $249 No picture. I don't know what this is. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Time/Filtering From: "Steve Hammond" shammon1@............. Date: Mon, 16 May 2005 23:41:05 -0700 Hi, I was thinking about simple ways to measure this and was able to use one of the unused channels on Larry's A/D board by splitting the unfiltered data from one of my sensors into it before it was filtered. After capturing some sample data, I picked a nice large spike from one of the datasets and was able to see an approximate 60ms delay when comparing the filtered and unfiltered datasets. I'm using the Pete Rowe filter design Amp/filter found at http://pw2.netcom.com/~shammon1/equip.htm#Electronics and this is consistent with what I expected to see. Regards, Steve Hammond PSN San Jose Aptos, CA -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Larry Cochrane Sent: Tuesday, May 10, 2005 11:44 PM To: psn-l@.............. Subject: Re: Time/Filtering Hi Bryan, If your A/D board was locked to GPS time your timing accuracy is closer to +-5ms. The filter delay is more or less constant and can be factor out by placing the filter delay time in WinSDR. In the Channel Settings dialog box you will see a "Filter Delay" edit box. For now use 50 ms. When I get some time I will measure the delay of one of my Amp/Filter board channels and place this information on my Web site. Besides accurate timing you should also have an accurate location of you station. I noticed that the PSN files you placed on your web site did not have the Latitude and Longitude data filled out or the file only had the location too two decimal places. Since you have a GPS receiver you can use it to locate you station's location to a few meters. If you run the current beta version of WinSDR you can use it to average the position information from the GPS receiver connected to the A/D board. See http://www.seismicnet.com/winsdr/betarelease.html for more information. If you let WinSDR average the data for a day or two you will have a very accurate latitude and longitude number. Regards, Larry Cochrane Bryan wrote: > Ok so what should I tell CERI I am getting a lot of different numbers from the replies? Would I be ok >to say with filtering I should be within +/- 50ms also will this be good enough to accurately locate >a local events with 3 stations less than 50 miles apart. This will explain why I ask is a clip >from a letter from Mitch. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Time/Filtering From: ChrisAtUpw@....... Date: Tue, 17 May 2005 07:33:22 EDT In a message dated 17/05/2005, shammon1@............. writes: Hi, I was thinking about simple ways to measure this and was able to use one of the unused channels on Larry's A/D board by splitting the unfiltered data from one of my sensors into it before it was filtered. After capturing some sample data, I picked a nice large spike from one of the datasets and was able to see an approximate 60ms delay when comparing the filtered and unfiltered datasets. I'm using the Pete Rowe filter design Amp/filter found at http://pw2.netcom.com/~shammon1/equip.htm#Electronics and this is consistent with what I expected to see. Regards, Steve Hammond PSN San Jose Aptos, CA Hi Steve, The component values on Pete Rowe's circuit diagrams on your Website are unfortunately almost unreadable on my computer. A three pole 10 Hz Butterworth filter should give about 30 milli sec delay, peaking to about 40 milli sec at 8 Hz. If you have a Butterworth filter and wait for a spike, you will probably be measuring the delay near the peak, rather than the low frequency delay which applies to P & S waves. Regards, Chris Chapman
In a message dated 17/05/2005, shammon1@............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Hi, I=20 was thinking about simple ways to measure this and was able to use one
= of=20 the unused channels on Larry's A/D board by splitting the unfiltered=20 data
from one of my sensors into it before it was filtered. After captu= ring=20 some
sample data,  I picked a nice large spike from one of the=20 datasets and was
able to see an approximate 60ms delay when comparing t= he=20 filtered and
unfiltered datasets. I'm using the Pete Rowe filter design= =20 Amp/filter found
at http://pw2.netcom.com/~shammon1/equip.htm#Electroni= cs=20 and this is
consistent with what I expected to see.
Regards, Steve=20 Hammond  PSN San Jose
Aptos, CA
Hi Steve,
 
    The component values on Pete Rowe's circuit=20 diagrams on your Website are unfortunately almost unreadable on my=20 computer.
    A three pole 10 Hz Butterworth filter should gi= ve=20 about 30 milli sec delay, peaking to about 40 milli sec at 8 Hz.
    If you have a Butterworth filter and wait for a= =20 spike, you will probably be measuring the delay near the peak, rather than t= he=20 low frequency delay which applies to P & S waves.
    Regards,
 
    Chris Chapman
Subject: ebay auction From: BOB BARNS royb1@........... Date: Thu, 19 May 2005 09:41:50 -0400 Teledyne Geotech Portacorder RV-320 Seismograph Item number: 7517344928 ends May 23 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Time/Filtering From: "Steve Hammond" shammon1@............. Date: Thu, 19 May 2005 10:43:46 -0700 Hi Chris, you are correct. I had a little free time today and took out my scope and my very old Preston Mod-135 Waveform Source Generator and created some test files. I'll email you and Larry the files off-line and anybody else that would like to see it. I generated test data at 1, 3, 5, 7 and 9-Hz at voltage levels of .5 .2 and 1 volt PP for each Hz range. I'm using Winquake to view the resulting datasets and with the Windquake X-scale set at one, can see that CH6 the unfiltered channel leads the filtered ATN channel by six clicks on a scale of 1 to 14 clicks which I estimate to be 57% of the scale range which should directly convert to 57MS if my calculations are correct... I guess my first question is what am I measuring? This is not just the filter, the circuit also includes, a 3-poll filter, an inverting stage with decoupling cap and then a final gain/leveling stage and whatever processing time the micro processor takes up. The three op-amps are op-27's and the A/D is Larry's 8-channel serial data collection system which is housed in another box connected via short 12-inch jumpers. Please take a look at the data and see what you think. Steve -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Tuesday, May 17, 2005 4:33 AM To: psn-l@.............. Subject: Re: Time/Filtering In a message dated 17/05/2005, shammon1@............. writes: Hi, I was thinking about simple ways to measure this and was able to use one of the unused channels on Larry's A/D board by splitting the unfiltered data from one of my sensors into it before it was filtered. After capturing some sample data, I picked a nice large spike from one of the datasets and was able to see an approximate 60ms delay when comparing the filtered and unfiltered datasets. I'm using the Pete Rowe filter design Amp/filter found at http://pw2.netcom.com/~shammon1/equip.htm#Electronics and this is consistent with what I expected to see. Regards, Steve Hammond PSN San Jose Aptos, CA Hi Steve, The component values on Pete Rowe's circuit diagrams on your Website are unfortunately almost unreadable on my computer. A three pole 10 Hz Butterworth filter should give about 30 milli sec delay, peaking to about 40 milli sec at 8 Hz. If you have a Butterworth filter and wait for a spike, you will probably be measuring the delay near the peak, rather than the low frequency delay which applies to P & S waves. Regards, Chris Chapman
Hi Chris, you are correct. I had a = little=20 free time today and took out my scope and my very old Preston Mod-135 = Waveform=20 Source Generator and created some test files. I'll email you and Larry = the files=20 off-line and anybody else that would like to see it. I generated test = data at 1,=20 3, 5, 7 and 9-Hz at voltage levels of .5 .2 and 1 volt PP for each Hz = range. I'm=20 using Winquake to view the resulting datasets and with the Windquake = X-scale set=20 at one, can see that CH6 the unfiltered channel leads the filtered ATN = channel=20 by six clicks on a scale of 1 to 14 clicks which I estimate to be  = 57% of=20 the scale range which should directly convert to 57MS if my = calculations=20 are correct...
 
I guess my first question is = what am=20 I measuring? This is not just the filter, the = circuit also=20 includes, a 3-poll filter, an inverting stage with decoupling cap and = then a=20 final gain/leveling stage and whatever processing time the micro = processor takes=20 up. The three op-amps are op-27's and the A/D is Larry's 8-channel = serial data=20 collection system which is housed in another box connected via = short=20 12-inch jumpers. Please take a look at the data and see what you=20 think.
 
Steve
-----Original Message-----
From:=20 psn-l-request@.............. = [mailto:psn-l-request@...............On Behalf=20 Of ChrisAtUpw@.......
Sent: Tuesday, May 17, 2005 4:33=20 AM
To: psn-l@..............
Subject: Re:=20 Time/Filtering

In a message dated 17/05/2005, shammon1@............. = writes:
Hi, I was = thinking about=20 simple ways to measure this and was able to use one
of the unused = channels on Larry's A/D board by splitting the unfiltered = data
from one=20 of my sensors into it before it was filtered. After capturing = some
sample=20 data,  I picked a nice large spike from one of the datasets and = was
able to see an approximate 60ms delay when comparing the = filtered=20 and
unfiltered datasets. I'm using the Pete Rowe filter design = Amp/filter=20 found
at http://pw2.netcom.com/~shammon1/equip.htm#Electronics = and this=20 is
consistent with what I expected to see.
Regards, Steve=20 Hammond  PSN San Jose
Aptos, = CA
Hi Steve,
 
    The component values on Pete Rowe's = circuit=20 diagrams on your Website are unfortunately almost unreadable on my=20 computer.
    A three pole 10 Hz Butterworth filter = should give=20 about 30 milli sec delay, peaking to about 40 milli sec at 8 Hz.
    If you have a Butterworth filter and wait = for a=20 spike, you will probably be measuring the delay near the peak, rather = than the=20 low frequency delay which applies to P & S waves.
    Regards,
 
    Chris=20 Chapman
Subject: ebay auctions From: BOB BARNS royb1@........... Date: Thu, 26 May 2005 10:21:47 -0400 Hi gang, VS-1200 Engineering Seismograph Sprengnether Co Item number: 7518967022 ends June 1 incls. the manual Teledyne Geotech Portacorder RV-320 Seismograph Item number: 7518959163 ends May 30 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auctions From: BOB BARNS royb1@........... Date: Fri, 27 May 2005 10:09:55 -0400 Hi gang, I don't normally report books on ebay but these are special: Quantitative Seismology - Aki, Keiiti/ Richards, *NEW Item number: 4547318309 Quantitative Seismology: Theory and Methods by Keiit,I Item number: 4548185179 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Phase picking From: Bobhelenmcclure@....... Date: Sat, 28 May 2005 17:24:27 EDT Hi all, I live on Long Island, New York. Local events are very rare here, so what I detect are mostly teleseisms. I consider myself pretty competent at the recording and signal processing of such events to obtain accurate broadband waveform reproduction and timing. My event waveforms correspond well with those of nearby LD network station PAL. I do not consider myself competent at P and S phase picking, and need advice. What is the criterion for judging phase arrival time? Is it the first velocity peak, emergent velocity, first displacement peak, emergent displacement, or what? Most of the S phases I record have fairly long period, and the P minus S time estimate depends greatly on the S phase time pick. Cheers, Bob (PSN station rem) Hi all,

  I live on Long Island, New York. Local events are very rare here, so=20= what I detect are mostly teleseisms.  I consider myself pretty competen= t at the recording and signal processing of such events to obtain accurate b= roadband waveform reproduction and timing. My event waveforms correspond wel= l with those of nearby LD network station PAL.

  I do not consider myself competent at P and S phase picking, and need= advice. What is the criterion for judging phase arrival time? Is it the fir= st velocity peak, emergent velocity, first displacement peak, emergent displ= acement, or what? Most of the S phases I record have fairly long period, and= the P minus S time estimate depends greatly on the S phase time pick.

Cheers,

Bob (PSN station rem)
Subject: ebay auction From: BOB BARNS royb1@........... Date: Mon, 30 May 2005 14:23:34 -0400 Electronic Micrometer, Seismograph, LVDT Transducer Item number: 6183156631 ends May 5 Handy device. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction From: ChrisAtUpw@....... Date: Mon, 30 May 2005 19:38:10 EDT In a message dated 30/05/2005, royb1@........... writes: Electronic Micrometer, Seismograph, LVDT Transducer Item number: 6183156631 ends May 5 Handy device. Bob Hi Bob, Ends June 5th! Umm? This looks like the type of LVDT which has an integral transistor square wave oscillator / diode rectifier demodulator. On the types that I have used, there was some feedthrough of the drive signal and the output / sensitivity did drift a bit with temperature. +/-0.1" is on the low end of the commercial range. I would expect it to be able to measure 1/10 thou OK. I would guess that 1/25 of this or less, 1 micron, would probably be down in the system noise. See _http://www.transtekinc.com/_ (http://www.transtekinc.com/) for more information. For the very high sensitivity low noise detectors for seismometers, you can use a sine wave drive and a FET IC phase sensitive detector, with an AC/AC sensor. Regards, Chris Chapman
In a message dated 30/05/2005, royb1@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2> =20   Electronic Micrometer, Seismograph, LVDT Transducer Item number:=20
6183156631 ends May 5
   Handy=20 device.
Bob
Hi Bob,
 
    Ends June 5th!
 
    Umm? This looks like the type of LVDT which has= an=20 integral transistor square wave oscillator / diode rectifier demodulator. On= the=20 types that I have used, there was some feedthrough of the drive signal and t= he=20 output / sensitivity did drift a bit with temperature. +/-0.1" is on the low= end=20 of the commercial range. I would expect it to be able to measure 1/10 thou O= K. I=20 would guess that 1/25 of this or less, 1 micron, would probably be down= in=20 the system noise. 
    See http://www.transtekinc.com/ fo= r more=20 information.
    For the very high sensitivity low noise detecto= rs=20 for seismometers, you can use a sine wave drive and a FET IC phase sensitive= =20 detector, with an AC/AC sensor.
 
    Regards,
 
    Chris Chapman
Subject: Missing links From: ChrisAtUpw@....... Date: Mon, 30 May 2005 19:47:56 EDT Hi Larry, The _New Manual of Seismological Observatory Practice_ (http://www.seismo.com/msop/nmsop/nmsop.html) Updated version of the link above. and _Instrumentation in Earthquake Seismology_ (http://www.geo.uib.no/seismo/SOFTWARE/DOCUMENTATION/instrument.pdf) (pdf file) by Jens Havskov and Gerardo Alguacil. are both showing as 'missing links'. Have you managed to measure the filter delays in your amplifier boards yet, please? Regards, Chris Chapman
Hi Larry,
 
    The=20
  • New Manual of=20 Seismological Observatory Practice Updated version of the link above. an= d=20
  • = Instrumentation=20 in Earthquake Seismology (pdf file) by Jens Havskov and Gerardo Alguacil= ..=20
  •      are both showing as 'missing links'.
     
        Have you managed to measure the filter delays i= n=20 your amplifier boards yet, please?
     
        Regards,
     
        Chris Chapman
    Subject: Eruption of Nevado volcano in the Calimo complex of Mexico From: meredith lamb paleoartifact@......... Date: Mon, 30 May 2005 22:37:45 -0600 Hi all, The following website has a interesting series of still shots of the=20 erupting volcano tonight. It essentially started off with a "bang". The volcano's there has a history of frequent eruptions. One has to download all the shots; and then they play back in more rapid succession. Web traffic might slow down visiting the website. http://www.ucol.mx/volcan/imagne.htm Meredith Lamb
    Hi all,
     
    The following website has a interesting series of still shots of the e= rupting
    volcano tonight.  It essentially started off with a "bang&qu= ot;.  The volcano's
    there has a history of frequent eruptions.  One has to download a= ll the
    shots; and then they play back in more rapid succession.  Web tra= ffic
    might slow down visiting the website.
     
     
    Meredith Lamb
     
    Subject: Re: Eruption of Nevado volcano in the Calimo complex of Mexico From: Canie canie@........... Date: Mon, 30 May 2005 22:31:03 -0700 Correct URL: http://www.ucol.mx/volcan/imagen.htm At 10:37 PM 5/30/2005 -0600, you wrote: >Hi all, > >The following website has a interesting series of still shots of the erupting >volcano tonight. It essentially started off with a "bang". The volcano's >there has a history of frequent eruptions. One has to download all the >shots; and then they play back in more rapid succession. Web traffic >might slow down visiting the website. > >http://www.ucol.mx/volcan/imagne.htm > >Meredith Lamb > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Eruption of Nevado volcano in the Calimo complex of Mexico From: John or Jan Lahr JohnJan@........ Date: Tue, 31 May 2005 07:52:30 -0600 I just returned from Costa Rica, where the weather cooperated and I was able to see Arenal volcano very clearly. There are some pictures and one video posted here: http://jclahr.com/science/earth_science/cientec/2005workshop/ Cheers, John At 11:31 PM 5/30/2005, Canie wrote: >Correct URL: >http://www.ucol.mx/volcan/imagen.htm __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Phase picking From: Larry Cochrane lcochrane@.............. Date: Tue, 31 May 2005 23:30:57 -0700 Hi Bob, WinQuake can be used to learn how to pick the P and S waves using known event information. To do this, the following things need to be correct: The data needs to be accurately timestamped and the location of the sensor must be known to a few meters. Nowadays, using GPS this shouldn't be a problem. The reporting agency needs to report the location, depth and event time correctly. The sensor to event distance must be under ~11000km do to the shadow effect of the earths core. If these things are correct WinQuake, using the travel time tables, can place the P and S markers very accurately on the seismogram. I'm constantly amazed at how accurate the travel-time tables can be. The waves can take over 10 minutes to get to the station and the calculated P wave arrival time is less then two or three seconds off from the actual arrival time. That's less then a 0.5% error. With a good signal to noise seismogram, the P wave should be easily picked no matter if the data is in acceleration, velocity or displacement. It's the point where you see the first out of noise signal from the event. Normally a vertical sensor will display the P wave more clearly then a horizontal sensor. Picking the S wave is much harder. A horizontal senor will display the S wave better so using this type of sensor makes it easier to pick the start of this wave. The depth of the event also makes a difference. With one seismogram it's hard to determine this parameter. One clue that the event is under 33 km is the lack of large surface waves. Regards, Larry Cochrane Redwood City, PSN Bobhelenmcclure@....... wrote: > Hi all, > > I live on Long Island, New York. Local events are very rare here, so what I > detect are mostly teleseisms. I consider myself pretty competent at the > recording and signal processing of such events to obtain accurate broadband > waveform reproduction and timing. My event waveforms correspond well with those of > nearby LD network station PAL. > > I do not consider myself competent at P and S phase picking, and need > advice. What is the criterion for judging phase arrival time? Is it the first > velocity peak, emergent velocity, first displacement peak, emergent displacement, > or what? Most of the S phases I record have fairly long period, and the P minus > S time estimate depends greatly on the S phase time pick. > > Cheers, > > Bob (PSN station rem) > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Missing HS 10 Geophone Plot From: ChrisAtUpw@....... Date: Wed, 1 Jun 2005 06:00:58 EDT Hi Larry, The _http://www.geospacelp.com/hs10.htm_ (http://www.geospacelp.com/hs10.htm) link for the characteristic curve of the HS 10 geophones on psn.quake.net seems to be broken. You can call _http://www.geospacelp.com/_ (http://www.geospacelp.com/) click on Seismology, click on HS-!0, scroll to the bottom of the page and Click _HERE_ (http://www.geospacelp.com/c_hs10.shtml) to load chart for Seismic Detector Response Curve Output VS. Frequency (HS-10 & HS-10-1B). (115 KBytes) Regards, Chris Chapman
    Hi Larry,
     
        The http://www.geospacelp.com/hs10.h= tm link=20 for the characteristic curve of the HS 10 geophones on psn.quake.net seems t= o be=20 broken.
     
        You can call http://www.geospacelp.com/  cli= ck on=20 Seismology, click on HS-!0, scroll to the bottom of the page and
    Click HERE=20 to load chart for Seismic Detector Response Curve Output VS. Frequency (HS-1= 0=20 & HS-10-1B). (115 KBytes)
     
        Regards,
     
        Chris Chapman
    Subject: national geographic web story From: meredith lamb paleoartifact@......... Date: Wed, 1 Jun 2005 11:06:38 -0600 Hi all, The National Geographic web site has a article titled: "Can the Moon Cause= =20 Earthquakes?" Their is "related" stories and websites also thereon...that are interesting= =20 light reading also.=20 http://news.nationalgeographic.com/news/2005/05/0523_050523_moonquake.html Meredith Lamb
    Hi all,
     
    The National Geographic web site has a article titled:  "Can= the Moon Cause Earthquakes?"
    Their is "related" stories and websites also thereon...that = are interesting light reading also. 
     
     
    Meredith Lamb
     
     
    Subject: 2nd seismograph From: 1goss@........... Date: Fri, 03 Jun 2005 05:41:22 +0000 I got my second seismograph running it is an East West instrument , and I recorded my first event on it. Here is the seismogram. Thanks for all the help Bryan S Goss Corinth Ms. https://home.comcast.net/~bryangoss/40.jpg Magnitude 3.9 TENNESSEE Thursday, June 02, 2005 at 11:35:11 UTC __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Eruption of Nevado volcano in the Calimo complex of Mexico From: "felipe luevanos luevanos" felicaribe5@........... Date: Fri, 03 Jun 2005 19:34:55 +0000

    Hi Meredith,

    The correct name of the Volcano is Colima.

    Felipe.




    >From: meredith lamb <paleoartifact@.........>
    >Reply-To: psn-l@..............
    >To: psn-l@..............
    >Subject: Eruption of Nevado volcano in the Calimo complex of Mexico
    >Date: Mon, 30 May 2005 22:37:45 -0600
    >
    >Hi all,
    >  The following website has a interesting series of still shots of the
    >erupting
    >volcano tonight. It essentially started off with a "bang". The volcano's
    >there has a history of frequent eruptions. One has to download all the
    >shots; and then they play back in more rapid succession. Web traffic
    >might slow down visiting the website.
    >  http://www.ucol.mx/volcan/imagne.htm
    >  Meredith Lamb


    Don't just search. Find. MSN Search Check out the new MSN Search! Subject: Re: 2nd seismograph From: George Bush ke6pxp@....... Date: Tue, 07 Jun 2005 12:37:13 -0700 Congratulations, and I am impressed on how low the noise is on your system (prior to the event). I live just a block away from the ocean and the swells give me a pretty high level of background noise. I would be curious on how you plan on processing the signals from your two axis. I also have N-S and E-W instruments and have been looking for some way to combine the two signals to create a vector of the signal. At 05:41 AM 6/3/05 +0000, you wrote: >I got my second seismograph running it is an East West instrument , >and I recorded my first event on it. Here is the seismogram. >Thanks for all the help Bryan S Goss Corinth Ms. > >https://home.comcast.net/~bryangoss/40.jpg > > >Magnitude 3.9 TENNESSEE >Thursday, June 02, 2005 at 11:35:11 UTC > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > George Bush Sea Ranch, CA, USA 38.73775N, 123.48882W __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 2nd seismograph From: 1goss@........... Date: Wed, 08 Jun 2005 18:19:53 +0000 George Thanks for the reply, I am processing the signals from the two axis separately. Larry,s boards will go up to four channels, I am using channel 1 and 2 they log independently. I don't plan on combining them I sure you can I am just starting out and am not sure how you would do that. Bryan S Goss > Congratulations, and I am impressed on how low the noise is on your system > (prior to the event). I live just a block away from the ocean and the > swells give me a pretty high level of background noise. > > I would be curious on how you plan on processing the signals from your two > axis. I also have N-S and E-W instruments and have been looking for some > way to combine the two signals to create a vector of the signal. > > At 05:41 AM 6/3/05 +0000, you wrote: > >I got my second seismograph running it is an East West instrument , > >and I recorded my first event on it. Here is the seismogram. > >Thanks for all the help Bryan S Goss Corinth Ms. > > > >https://home.comcast.net/~bryangoss/40.jpg > > > > > >Magnitude 3.9 TENNESSEE > >Thursday, June 02, 2005 at 11:35:11 UTC > > > >__________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email PSN-L-REQUEST@.............. with > >the body of the message (first line only): unsubscribe > >See http://www.seismicnet.com/maillist.html for more information. > > > > George Bush > Sea Ranch, CA, USA > 38.73775N, 123.48882W > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: news: Quake may be 'imminent' warns tsunami expert From: Mark Robinson mark.robinson@............... Date: Thu, 09 Jun 2005 16:38:41 +1200 http://www.stuff.co.nz/stuff/print/0,1478,3308084a10,00.html Quake may be 'imminent' warns tsunami expert 09 June 2005 By RICHARD MACE A scientist who predicted the second Indonesian earthquake fears a third devastating jolt, powerful enough to cause another major tsunami, is "imminent". The waves could sweep north-western Australia, reaching as far as Perth. John McCloskey, of the University of Ulster, said building the Indian Ocean tsunami warning system was "an urgent priority". "Don't take the foot off the gas. This is very urgent work." In mid March, Professor McCloskey warned that the Boxing Day quake, which triggered the tsunami that killed 300,000 people, had shifted tectonic stresses to another spot on Sumatra's geological fault line. He predicted a second strong quake, noting many did not believe lightning could strike twice. "But with earthquakes it's exactly the opposite ... I quite honestly hope we're completely wrong." He wasn't. The second quake, measuring 8.3, struck on March 28 near the Simeulue and Nias islands, killing 2000 people. In a new study, published in Nature, Professor McCloskey's team reports that "stresses imposed by the second rupture have brought closer to failure" another zone "immediately to the south, under the Batu and Mentawai islands". "The historical record and the experience of the Sumatra-Andaman and Simeulue-Nias events indicate that a tsunami could be a possibility." Professor McCloskey told the Sydney Morning Herald it would likely strike near the Mentawai islands, triggering a repeat performance of the 8.5 quake of 1833. "The 1833 earthquake is probably a reasonable model. It did trigger a tsunami and there were many casualties. That's the type of earthquake we fear it definitely could be." Professor McCloskey noted that the 1833 tsunami reached north-western Australia. Next time "the waves would be felt in Perth," he said, adding he could not say how strong they would be. It was impossible to say when it would happen, but the evidence, including historical data, showed it could be within 30 years, following the pattern of the 1833 and 1861 Sumatra quakes. "It may be sooner. We must assume it's imminent and behave accordingly. We can't bury our heads in the sand." Commenting on his last prediction, Professor McCloskey said: "I've very mixed feelings." He had "a sense of professional satisfaction that our science has started to understand well" earthquakes. "I hope I am wrong this time, but I don't think so. It's not something you get any pleasure out of ... even though with the last one we were very accurate." While a "high tech" warning system would protect people around the Indian Ocean, there would be no time to alert Sumatra. A program was needed to teach them how to save themselves. "People need to plan what to do in Sumatra when they feel the earth shake. You have 15 to 20 minutes to get yourself into a position safe from the tsunami." __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 2nd seismograph From: Bobhelenmcclure@....... Date: Sat, 11 Jun 2005 20:56:47 EDT On Tue, 07 Jun 2005, George Bush wrote: >I would be curious on how you plan on processing the signals from your two >axis. I also have N-S and E-W instruments and have been looking for some >way to combine the two signals to create a vector of the signal. Hi George, Winquake does not provide 2D plotting, but I have my own way, using Dataq's WinDaq Lite Waveform Browser, which can be downloaded from "www.dataq.com" free of charge. I have written a utility program "Headpik.exe" which, among its many other functions, can convert PSN Type 4 files to WinDaq (.WDQ) format files. "Headpik.exe" can then combine two such files into a 2-channel WinDaq file, which can be displayed in X-Y format by the WinDaq Lite Waveform Browser. You can also view a superimposed plot of X and Y, something else that WinQuake does not provide. If you have any interest, contact me at bobhelenmcclure at aol dot com. Fair warning: It will take a lot of time to learn how to use the WinDaq Browser. Since I use Dataq hardware and software for data acquisition, I had no choice in having to learn how to use their software. You may not be as motivated. Given sufficient popular demand, I could build an application for 2D viewing of PSN event files without resort to any other supporting software. However, I also note that very few PSN members record on both N and E channels. It is necessary that the sensors have the same response bandwidth and sensitivity. If they do not, I have an application, "WQFilter.exe", which can be used to make the channel responses the same. Cheers, Bob McClure On Tue, 07 Jun 2005, George Bush wr= ote:
    >I would be curious on how you plan on processing the signals from your t= wo
    >axis. I also have N-S and E-W instruments and have been looking for some=
    >way to combine the two signals to create a vector of the signal.

    Hi George,

      Winquake does not provide 2D plotting, but I have my own way, using D= ataq's
    WinDaq Lite Waveform Browser, which can be downloaded from "www.dataq.com" <= BR> free of charge. I have written a utility program "Headpik.exe" which, among=20= its
    many other functions, can convert PSN Type 4 files to WinDaq (.WDQ) format <= BR> files. "Headpik.exe" can then combine two such files into a 2-channel WinDaq=
    file, which can be displayed in X-Y format by the WinDaq Lite Waveform Brows= er.
    You can also view a superimposed plot of X and Y, something else that WinQua= ke
    does not provide. If you have any interest, contact me at
    bobhelenmcclure at aol dot com.

      Fair warning: It will take a lot of time to learn how to use the WinD= aq Browser.
    Since I use Dataq hardware and software for data acquisition, I had no choic= e
    in having to learn how to use their software. You may not be as motivated. G= iven
    sufficient popular demand, I could build an application for 2D viewing of PS= N
    event files without resort to any other supporting software. However, I also= note
    that very few PSN members record on both N and E channels. It is necessary t= hat
    the sensors have the same response bandwidth and sensitivity. If they do not= ,
    I have an application, "WQFilter.exe", which can be used to make the channel=
    responses the same.

    Cheers,

    Bob McClure
    Subject: Re: 2nd seismograph From: George Bush ke6pxp@....... Date: Mon, 13 Jun 2005 11:31:07 -0700 Subject: Re: Posting Events From: Larry Cochrane lcochrane@.............. Date: Tue, 14 Jun 2005 02:01:32 -0700 Hi Bryan, > What letters should I use I used bg1 on this I posted > > 050613.224901.bg1.psn Magnitude 7.9 - TARAPACA, CHILE (GIF Image) I checked and bg1 bg2 etc have not been used before by another PSN station, so you can use these IDs for your station. Another option is to use bgn and bge for your two sensors. If you want to do this let me know and I will change the event file you just sent in. > The "from corinth Ms" did not show up what do I need to do to correct > it. This is done at your end using WinQuake's Event Report feature. This feature can be used to add event information to your event files using a reporting agency like the USGS. See the WinQuake documentation for more information. I updated the event file you sent in with the current information for the USGS. I noticed that the P and S waves markers in WinQuake did not match up correctly with the actual start of these waves in your event file. After updating your file with the correct depth information the P and S wave locations calculated by WinQuake are much better. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Two N. Cal. quakes on June 14 From: "Keith Payea" kpayea@........... Date: Wed, 15 Jun 2005 08:56:27 -0700 Last night there was a 7+ earthquake off the California coast near Eureka at 19:50 local time. About seven minutes later, there was a 3.9 at the Geysers. On my monitor, the one from the Geysers overlaps the tail of the one from the coast. Has anyone else noticed this also? It seems that the 3.9 at the Geysers happened right around the time that the waves from the 7 in Eureka passed through the area. I hate to draw too much of a conclusion because there are so many quakes at the Geysers. However, 3.9 and bigger are much less frequent than the 1's and 2's that clutter up the maps. Does anyone else feel these two are linked? I'll post a plot in a little while. Cheers, Keith Keith Payea Bryant Labs kpayea@.............. www.bryantlabs.net (707) 566-8935 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Offshore quake... From: "Kareem at HeyJooJoo" system98765@............. Date: Wed, 15 Jun 2005 18:51:32 -0700 Well, that area has had similar events before. See what excessive TV coverage of quake disasters cause. Now the government has to contend with people griping about whether a tsunami warning should have even been issued. Hearing that EBS alert on the radio yesterday due to an earthquake and tsunami threat was quite exciting. I've heard those before but they were always attributed to amber alerts and severe weather - never heard one for a quake. Anyway.... But I really wanted to point out something else, although a bit different from Keith's contribution. I discovered that yesterday's M7 event left a smaller signature on my drum while the M7 Hector Mines event in 1999 left a more dramatic one. Both events were very similar in magnitude (the MFZ event may have been a bit larger M7.2) and both are just about similar distances from my recording station. But I'm not sure why the seismogram signatures are sooooo different. The 1999 Hector event saturated my record for about six to seven minutes while yesterday's off-shore event never saturated, although the durations were about the same. My system is a short period sensor L4 geophone. The Gain was set at 30dB during the 1999 and yesterday, it was either at 18 or 24dB. Could it be that the MFZ event was submarine and the Hector Mines event was not? I dunno. What do you think? Kareem __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Triggers From: "albert judge" martinobs@.............. Date: Thu, 16 Jun 2005 21:30:18 +0800 Hi Keith, My name is Alby I run a station just to the east of Perth, Western = Australia. Just east of my station is an area called the South West Seismic Zone = which is the most active earthquake zone in Australia. I often note what I call triggers, one event seeming to trigger another = as you mention regarding the California M7 event. I recorded a M4 event 40 minutes after the Boxing Day earthquake, this = M4 event was in the SWSZ in a new area that became active in November = last year. On Sunday night I recorded a M4.3 event at a place called Cadoux = followed 8 hours later by a M4.5 event 30km away at a siding called = Burakin. This occurs frequently. As to the mechanism, who knows? Rapid stress transfer, harmonic activation of a nearby fault primed to = go? Anyway I thought your observation interesting as it struck a chord with = my observations here. By the way for further info on this check out the Landers event of 1992 = in Southern California. Cheers, Alby. Martin Observatory
    Hi Keith,
    My name is Alby I run a station just to = the east of=20 Perth, Western Australia.
    Just east of my station is an area = called the South=20 West Seismic Zone which is the most active earthquake zone in=20 Australia.
    I often note what I call triggers, one = event=20 seeming to trigger another as you mention regarding the California M7=20 event.
    I recorded a M4 event 40 minutes after = the Boxing=20 Day earthquake, this M4 event was in the SWSZ in a new area that became = active=20 in November last year.
    On Sunday night I recorded a M4.3 event = at a place=20 called Cadoux followed 8 hours later by a M4.5 event 30km away at a = siding=20 called Burakin.
    This occurs frequently.
    As to the mechanism, who = knows?
    Rapid stress transfer, harmonic = activation of a=20 nearby fault primed to go?
    Anyway I thought your observation = interesting as it=20 struck a chord with my observations here.
    By the way for further info on this = check out the=20 Landers event of 1992 in Southern California.
    Cheers,
    Alby.
    Martin = Observatory
    Subject: Filter characteristics and signal delays From: ChrisAtUpw@....... Date: Thu, 16 Jun 2005 21:08:04 EDT Hi All, You may remember that there was a discussion a while back concerning the signal delays produced by the filter circuits used in seismic amplifiers. After waiting patiently for any figures to be produced, I eventually gave up and plugged the filter components shown on the circuit diagrams of two of Larry's amplifiers into experimenter board. I then made some approximate measurements for the characteristics and the signal delays. I have put approx. after readings of less that - 30 dB, since the signals had a significant noise component from the opamp chains. The capacitors were selected from a 5% polyester range. I used a Wayne Kerr FG3 Function Generator down to 0.01 Hz and a Philips PM3217 dual beam oscilloscope. I also checked the frequency calibration of the Function Generator with a counter timer. The test signals used were continuous wave, not 2 (or more) cycle sine wave transient signals (a signal which starts on zero, follows a sine wave pattern for two cycles and finishes on zero, followed by a zero level pause). The 'older' type of amplifier circuit used 4 off LF412 opamps in a 6 pole filter circuit, nominally rated at 10 Hz turnover with a Butterworth characteristic. This circuit is no longer in production, but I am sure that many are still in use. The measured signal delay was about 60 milli sec at 1 Hz and increased to about 70 milli sec at 10 Hz. The gains were 10 Hz -5.4 dB 15 Hz -20 dB 20 Hz -35 dB approx. The 'newer' 1 to 3 channel type amplifier uses a TL074 opamp in an 8 pole filter circuit, nominally rated at 5 Hz with a Butterworth characteristic for the Lehman configuration - see _http://psn.quake.net/eqamp.html_ (http://psn.quake.net/eqamp.html) The measured delay was 100 milli sec at 1 Hz and it was very nearly constant out to 5 Hz. The gains were 5 Hz -2.2dB 7.5 Hz -7.3 dB 10 Hz -14 dB 15 Hz -32 db approx. The 'newer' type with the geophone configuration is rated at 10 Hz with a Butterworth characteristic. The component values in the panel on the circuit diagram give a 10 Hz turnover, not the 20 Hz stated. I note that there is still considerable signal gain at 20 Hz, which may be relevant when considering environmental noise pickup at your location. The measured delay at 1 Hz was 48 milli sec and this appeared to stay constant out to 10 Hz. The gains were 10 Hz -2.2 dB 15 Hz -6.8 dB 20 Hz -14 dB 30 Hz -33 dB approx. I did not find any peaks in the delay characteristics of the TL074 opamp filter types at about 0.8 x the cut-off frequency, as shown on Texas' FilterPro design plots for Butterworth Filters. Comparing this filter output characteristic with the older 6 pole Butterworth filter suggests a more gradual 'roll off' and near constant signal delays over the passband, more characteristic of Bessel type filters. I did not test the latest 8 pole version of the 1 to 4 channel amplifier filter which uses a LF444 opamp, but I would expect them to be similar. The plots of the characteristics appear to be identical. See _http://psn.quake.net/serialamp.html_ (http://psn.quake.net/serialamp.html) If you are digitising several channels with the same A/D conveter, it may be worth measuring / calculating the delay in between the channel readings. Even if a conversion only takes ~20 micro seconds, the 'speed' of the digital link to the computer may need to be considered. These signal delays are of the same order as the errors which may be produced in estimating the start time of the signal and are probably not significant for most 'amateur' work. If, however, you apply a 'real' narrow band multi pole filter at about 0.5 or 1 Hz to the signal to dig P & S waves out of the general background, much larger timing errors can be produced. I have no information on narrow band software filters. Regards, Chris Chapman
    Hi All,
     
        You may remember that there was a discussion a=20 while back concerning the signal delays produced by the filter circuits used= in=20 seismic amplifiers.
     
        After waiting patiently for any figures to be=20 produced, I eventually gave up and plugged the filter components shown on th= e=20 circuit diagrams of two of Larry's amplifiers into experimenter board. I the= n=20 made some approximate measurements for the characteristics and the signal=20 delays. I have put approx. after readings of less that - 30 dB, since t= he=20 signals had a significant noise component from the opamp chains.
     
        The capacitors were selected from a 5% polyeste= r=20 range. I used a Wayne Kerr FG3 Function Generator down to 0.01 Hz and a Phil= ips=20 PM3217 dual beam oscilloscope. I also checked the frequency calibration of t= he=20 Function Generator with a counter timer. The test signals used were=20 continuous wave, not 2 (or more) cycle sine wave transient signals (a signal= =20 which starts on zero, follows a sine wave pattern for two cycles and finishe= s on=20 zero, followed by a zero level pause).
     
        The 'older' type of amplifier circuit used 4 of= f=20 LF412 opamps in a 6 pole filter circuit, nominally rated at 10 Hz turnover w= ith=20 a Butterworth characteristic. This circuit is no longer in production, but I= am=20 sure that many are still in use.
        The measured signal delay was about 60 milli se= c at=20 1 Hz and increased to about 70 milli sec at 10 Hz.
        The gains were
    10 Hz    -5.4 dB
    15 Hz    -20 dB
    20 Hz    -35 dB approx.
     
        The 'newer' 1 to 3 channel type amplifier uses=20= a=20 TL074 opamp in an 8 pole filter circuit, nominally rated at 5 Hz with a=20 Butterworth characteristic for the Lehman configuration - see http://psn.quake.net/eqamp.html=
        The measured delay was 100 milli sec at 1 Hz an= d it=20 was very nearly constant out to 5 Hz.
        The gains were
      5 Hz    -2.2dB
    7.5 Hz    -7.3 dB
    10 Hz    -14 dB
    15 Hz    -32 db approx.
     
        The 'newer' type with the geophone configuratio= n is=20 rated at 10 Hz with a Butterworth characteristic. The component values in=20 the panel on the circuit diagram give a 10 Hz turnover, not t= he=20 20 Hz stated. I note that there is still considerable signal gain at 20= Hz,=20 which may be relevant when considering environmental noise pickup at your=20 location.
        The measured delay at 1 Hz was 48 milli sec and= =20 this appeared to stay constant out to 10 Hz.
        The gains were
    10 Hz    -2.2 dB
    15 Hz    -6.8 dB
    20 Hz    -14 dB
    30 Hz    -33 dB approx.
     
        I did not find any peaks in the delay=20 characteristics of the TL074 opamp filter types at about 0.8 x the cut-off=20 frequency, as shown on Texas' FilterPro design plots for Butterworth=20 Filters. Comparing this filter output characteristic with the older 6 p= ole=20 Butterworth filter suggests a more gradual 'roll off' and near constant sign= al=20 delays over the passband, more characteristic of Bessel type filters.
     
        I did not test the latest 8 pole version of the= 1=20 to 4 channel amplifier filter which uses a LF444 opamp, but I would expect t= hem=20 to be similar. The plots of the characteristics appear to be identical.= See=20 http://psn.quake.net/serialamp.= html
     
        If you are digitising several channels with the= =20 same A/D conveter, it may be worth measuring / calculating the delay in betw= een=20 the channel readings. Even if a conversion only takes ~20 micro seconds, the= =20 'speed' of the digital link to the computer may need to be considered.
     
        These signal delays are of the same order as th= e=20 errors which may be produced in estimating the start time of the signal= and=20 are probably not significant for most 'amateur' work. If, however, you apply= a=20 'real' narrow band multi pole filter at about 0.5 or 1 Hz to the=20 signal to dig P & S waves out of the general background, much larger tim= ing=20 errors can be produced. I have no information on narrow band software=20 filters.
     
        Regards,
     
        Chris Chapman
    Subject: URL of Southern CA and national event reports URL's From: "Steve Hammond" shammon1@............. Date: Fri, 17 Jun 2005 13:43:39 -0700 HI- I've been having trouble again finding the IP addresses for the Southern California and world-wide event reports that will work with Winquake. Can somebody give me the IP addresses you have been using? Thanks, Steve Hammond __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: URL of Southern CA and national event reports URL's From: Larry Cochrane lcochrane@.............. Date: Fri, 17 Jun 2005 22:29:24 -0700 Hi Steve, I use this report file ftp://hazards.cr.usgs.gov/cnss/cnss_14.fing. It's a composite list maintained by the USGS of events for the past 14 days. You will need to update your Report.dat and Network.dat files in the WinQuake directory to use the service above. This zip file http://www.seismicnet.com/software/EventReportFiles.zip contains the updated files. Larry Cochrane Redwood City, PSN Steve Hammond wrote: > HI- I've been having trouble again finding the IP addresses for the Southern > California and world-wide event reports that will work with Winquake. Can > somebody give me the IP addresses you have been using? > Thanks, > Steve Hammond > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: URL of Southern CA and national event reports URL's From: "Steve Hammond" shammon1@............. Date: Sat, 18 Jun 2005 11:25:49 -0700 Thanks-- That worked great. Thanks for including the updated ZIP file. Steve -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Larry Cochrane Sent: Friday, June 17, 2005 10:29 PM To: psn-l@.............. Subject: Re: URL of Southern CA and national event reports URL's Hi Steve, I use this report file ftp://hazards.cr.usgs.gov/cnss/cnss_14.fing. It's a composite list maintained by the USGS of events for the past 14 days. You will need to update your Report.dat and Network.dat files in the WinQuake directory to use the service above. This zip file http://www.seismicnet.com/software/EventReportFiles.zip contains the updated files. Larry Cochrane Redwood City, PSN Steve Hammond wrote: > HI- I've been having trouble again finding the IP addresses for the Southern > California and world-wide event reports that will work with Winquake. Can > somebody give me the IP addresses you have been using? > Thanks, > Steve Hammond > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Problem sending event files From: Robert Laney faultshake@......... Date: Thu, 23 Jun 2005 16:33:17 -0700 (PDT) All: I have run into a problem trying to submit an email of event files via AOL. When I click on SEND in Winquake I get an error message that says “Close Socket Error.” Although it has been several weeks since I sent my last event file, there have been no changes in the entries for SMTP, SMTP server, SMTP port number, etc., and the system worked fine at that time (I am using smtp.aol.com with the port set to 587 as per Larry‘s instructions for those using AOL). I tried contacting AOL tech services, but either I couldn't explain the problem clearly enough, or they didn't have any idea what I was talking about. I tried using yahoo in the smtp slot, but this didn't work either, I guess because I have to access Yahoo using AOL. Does Yahoo have downloadable software to enable one to contact them directly and bypass AOL? I looked on their web page, but didn't find anything along these lines. To make sure the problem wasn't something I had done on my fairly new notebook computer, I tried sending the event files on my old computer and I got the same error message. Has anyone else using AOL had this problem and/or could shed some light on dealing with the error message “Close Socket Error“? Thanks. Bob Laney Salem, Oregon --------------------------------- Do you Yahoo!? Make Yahoo! your home page

    All:

    I have run into a problem trying to submit an email of event files via AOL. When I click on SEND in Winquake I get an error message that says “Close Socket Error.” Although it has been several weeks since I sent my last event file, there have been no changes in the entries for SMTP, SMTP server, SMTP port number, etc., and the system worked fine at that time (I am using smtp.aol.com with the port set to 587 as per Larry‘s instructions for those using AOL).

    I tried contacting AOL tech services, but either I couldn't explain the problem clearly enough, or they didn't have any idea what I was talking about.

    I tried using yahoo in the smtp slot, but this didn't work either, I guess because I have to access Yahoo using AOL. Does Yahoo have downloadable software to enable one to contact them directly and bypass AOL? I looked on their web page, but didn't find anything along these lines.

    To make sure the problem wasn't something I had done on my fairly new notebook computer, I tried sending the event files on my old computer and I got the same error message.

    Has anyone else using AOL had this problem and/or could shed some light on dealing with the error message “Close Socket Error“?

    Thanks.

    Bob Laney

    Salem, Oregon


    Do you Yahoo!?
    Make Yahoo! your home page Subject: test From: "Connie and Jim Lehman" lehmancj@........... Date: Fri, 24 Jun 2005 16:47:07 -0400 xxx
    xxx
    Subject: earth tide tables From: BOB BARNS royb1@........... Date: Fri, 24 Jun 2005 20:06:29 -0400 Hi gang, A friend has several high precision pendulum clocks (and has built 2 others). He asked me to inquire of this list about where to get tables of earth tide data so that he can compare changes in the local value of g to daily variations of period which he sees in his clocks. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: earth tide tables From: "Randy Kimball" randy.kimball@........... Date: Fri, 24 Jun 2005 19:40:20 -0500 No, .. yes, .... well not exactly.... This is a free URL to a FREE program that provides tide information. It gets the info somewhere and claims to provide it for 9000 locations... that can't hurt to offer along. http://www.wxtide32.com/ -randy- -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of BOB BARNS Sent: Friday, June 24, 2005 7:06 PM To: psn mail Subject: earth tide tables Hi gang, A friend has several high precision pendulum clocks (and has built 2 others). He asked me to inquire of this list about where to get tables of earth tide data so that he can compare changes in the local value of g to daily variations of period which he sees in his clocks. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: June issue of Physics Today From: "Connie and Jim Lehman" lehmancj@........... Date: Fri, 24 Jun 2005 21:51:55 -0400 PSN folks--No doubt there will be sources hashing and re-hashing for = some time, the disasterous quake-12/26/04 and resulting tsunamis. In = the current June issue of Physics Today, David Stevenson of Cal Tech = has a two page summary of the dynamics of the rupture, the tremendous = energy released, and the physics of how it played out. This is worthwhile reading for anyone who copies events, and wishes to = know more about what is happening at the source in a big oceanic event. = Jim
    PSN folks--No doubt there will = be sources=20 hashing and re-hashing for some time, the disasterous = quake-12/26/04 and=20 resulting tsunamis.  In the current June issue = of Physics=20 Today,  David Stevenson of Cal Tech has a two  page = summary of=20 the dynamics of the rupture, the tremendous energy released, and the = physics of=20 how it played out.
      This is worthwhile reading for = anyone who=20 copies events, and wishes to know more about what is happening at = the=20 source in a big  oceanic=20 event.           &= nbsp;           &n= bsp;       =20 Jim
    Subject: Re: earth tide tables From: ChrisAtUpw@....... Date: Fri, 24 Jun 2005 23:43:09 EDT In a message dated 25/06/2005, royb1@........... writes: A friend has several high precision pendulum clocks (and has built 2 others). He asked me to inquire of this list about where to get tables of earth tide data so that he can compare changes in the local value of g to daily variations of period which he sees in his clocks. Hi Bob, If my memory is correct, the tide effects are at the 0.1 ppm level and below. 1 ppm is about 1 sec every 11.57 days. You don't say what level of accuracy he is aiming at. Three serious problems are providing adequate thermal compensation, removing the effects of variations in the angle of swing and removing seismic / environmental motion changes - particularly the ocean background. Dual coupled pendulums working in antiphase can be an advantage here. The pendulums need to be in airtight casings to remove atmospheric density changes. Providing a high vacuum will show greatly increased Qs, up to maybe a million, mostly below 10^-3 torr. The ecitation and the relation of it to the timing of the swing are critical. He needs to correlate drifts with daily changes to remove solar heating, ground tilts, weather effects..... The NAWCC science chapter 161 _http://www.ubr.com/clocks/nawcc/hsc/hsc.html_ (http://www.ubr.com/clocks/nawcc/hsc/hsc.html) has a lot of worthwhile articles in their archives. Regads, Chris Chapman
    In a message dated 25/06/2005, royb1@........... writes:
    <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>  A=20 friend has several high precision pendulum clocks (and has built 2=20
    others).
       He asked me to inquire of this list about whe= re=20 to get tables of
    earth tide data so that he can compare changes in the= =20 local value of g
    to daily variations of period which he sees in his=20 clocks.
    Hi Bob,
     
        If my memory is correct, the tide effects are a= t=20 the 0.1 ppm level and below. 1 ppm is about 1 sec every 11.57 days. You don'= t=20 say what level of accuracy he is aiming at. Three serious problems are provi= ding=20 adequate thermal compensation, removing the effects of variations in the ang= le=20 of swing and removing seismic / environmental motion changes - particularly=20= the=20 ocean background. Dual coupled pendulums working in antiphase can be an=20 advantage here. The pendulums need to be in airtight casings to remove=20 atmospheric density changes. Providing a high vacuum will show greatly incre= ased=20 Qs, up to maybe a million, mostly below 10^-3 torr. The ecitation and the=20 relation of it to the timing of the swing are critical. He needs to=20 correlate drifts with daily changes to remove solar heating, ground tilts,=20 weather effects.....
     
        The NAWCC science chapter 161 http://www.ubr.com/clo= cks/nawcc/hsc/hsc.html has=20 a lot of worthwhile articles in their archives.
     
        Regads,
     
        Chris Chapman
    Subject: Re: June issue of Physics Today From: Larry Cochrane lcochrane@.............. Date: Sat, 25 Jun 2005 02:55:47 -0700 It looks like the article is online here http://www.physicstoday.org/vol-58/iss-6/p10.html Larry Cochrane Redwood City, PSN Connie and Jim Lehman wrote: > PSN folks--No doubt there will be sources hashing and re-hashing for some time, the disasterous quake-12/26/04 and resulting tsunamis. In the current June issue of Physics Today, David Stevenson of Cal Tech has a two page summary of the dynamics of the rupture, the tremendous energy released, and the physics of how it played out. > This is worthwhile reading for anyone who copies events, and wishes to know more about what is happening at the source in a big oceanic event. Jim > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Earthworm, Winston, Swarm, PAR1CH From: Angel sismos@.............. Date: Sat, 25 Jun 2005 19:35:37 -0500 Hi Everyone, One of the things I miss most since I stopped using SDR is the wonderful GUI and alarm features that it had. I just liked it and haven't found anything that even comes close until now. I stopped using SDR when the PSN format went from 3 to 4. I recently have been playing with Earthworm and Seiscomp. I have an Earthworm system that gathers data from Galapagos, Venezuela, Costa Rica, Mexico and Puerto Rico and I was training it to locate in near real time. One of the limitations to using these two free and widely used softwares locally is that the digitizers that they connect to cost more than my car. Then I stumbled across a 24 bit digitizer that had a "module" for Earthworm that cost $150.00. Coincidentally at the same time I visited the Cascade Volcano Observatory and saw a program called Swarm written in Java and the GUI was great! Not as nice as SDR and lacking many of SDR's wonderful features but certainly an approaching second. Now this is what I have on my current experimental system. I have an L4C directly into a PAR1CH 24 bit single channel digitizer (no amp needed for this even though for a Lehman or 4.5 Hz geophone you will need an amp) I get GPS time with an Oncore GT connected to one of Larry's boards to time stamp the PAR1CH data. The data goes into an Earthworm "ring" and then I use an export module to feed data to Swarm over TCP/IP. This means that the data acquisition computer and the data display computer can be joined by any internet connection, from your garage to your desk or from your garage to my desk. Swarm can take data from any earthworm server so it can display both a real data squiggle and a heliocorder for any number of TCP/IP connected stations. All this is fun in itself but what make this more exciting is that any of us that had good full time internet connections could share data real time and all the stations that had good time could be joined to make a huge virtual network that could locate in real time. The installation of Earthworm is not a snap but it is not hard. The documentation is lacking. Anyone can have very good seismic station without a seismograph. There are many many data streams available from all over the world. One of my current "BIG" projects is to join all of Central America observatories into Virtual network by getting every country to get at least one broadband to stream data in real time to anyone who want it. I would be glad to help as best I can anyone that wants to try to get an Earthworm/Swarm/Winston setup going. To start most any ole computer that runs will do. Earthworm can write data in many formats and I think that one of them can be read by WinQuake. By the end of the summer I hope that there will be a Seiscomp "plug-in" for the boards made be Mauro Mariotti so we could connect inexpensive 3 channel station to Earthworms. Joachim Saul of GFZ is getting that going. Here are some URL for what I have mentioned above. I can send anyone who want a screen shot of the Swarm GUI. Regards, Angel PARxCH digitizers available from: www.symres.com Kip there has been very helpful. Earthworm is available from: http://folkworm.ceri.memphis.edu/ew-doc/ Seiscomp is available from: http://www.gfz-potsdam.de/geofon/new/scp.html Swarm is available from: http://www.stanford.edu/~dcerv/swarm/ Winston: http://www.avo.alaska.edu/Software/ Swarm and Winston are beta and Earthworm is 6.2 with 6.3 coming out soon. Seiscomp is work in progress. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthworm, Winston, Swarm, PAR1CH From: "JAMES C. ALLEN" jcallen1@........... Date: Sat, 25 Jun 2005 18:08:42 -0700 Can you configure swarm to utilize Larry's WinSDR and/or Winquake output? Jim ----- Original Message ----- From: "Angel" To: Sent: Saturday, June 25, 2005 5:35 PM Subject: Earthworm, Winston, Swarm, PAR1CH > Hi Everyone, > > One of the things I miss most since I stopped using SDR is the > wonderful GUI and alarm features that it had. I just liked it and > haven't found anything that even comes close until now. I stopped > using SDR when the PSN format went from 3 to 4. > > I recently have been playing with Earthworm and Seiscomp. I have an > Earthworm system that gathers data from Galapagos, Venezuela, Costa > Rica, Mexico and Puerto Rico and I was training it to locate in near > real time. > > One of the limitations to using these two free and widely used > softwares locally is that the digitizers that they connect to cost > more than my car. Then I stumbled across a 24 bit digitizer that had a > "module" for Earthworm that cost $150.00. Coincidentally at the same > time I visited the Cascade Volcano Observatory and saw a program > called Swarm written in Java and the GUI was great! Not as nice as SDR > and lacking many of SDR's wonderful features but certainly an > approaching second. > > Now this is what I have on my current experimental system. I have an > L4C directly into a PAR1CH 24 bit single channel digitizer (no amp > needed for this even though for a Lehman or 4.5 Hz geophone you will > need an amp) I get GPS time with an Oncore GT connected to one of > Larry's boards to time stamp the PAR1CH data. The data goes into an > Earthworm "ring" and then I use an export module to feed data to Swarm > over TCP/IP. This means that the data acquisition computer and the > data display computer can be joined by any internet connection, from > your garage to your desk or from your garage to my desk. Swarm can > take data from any earthworm server so it can display both a real data > squiggle and a heliocorder for any number of TCP/IP connected > stations. > > All this is fun in itself but what make this more exciting is that any > of us that had good full time internet connections could share data > real time and all the stations that had good time could be joined to > make a huge virtual network that could locate in real time. > > The installation of Earthworm is not a snap but it is not hard. The > documentation is lacking. Anyone can have very good seismic station > without a seismograph. There are many many data streams available from > all over the world. > > One of my current "BIG" projects is to join all of Central America > observatories into Virtual network by getting every country to get at > least one broadband to stream data in real time to anyone who want it. > > I would be glad to help as best I can anyone that wants to try to get > an Earthworm/Swarm/Winston setup going. To start most any ole computer > that runs will do. Earthworm can write data in many formats and I > think that one of them can be read by WinQuake. > > By the end of the summer I hope that there will be a Seiscomp > "plug-in" for the boards made be Mauro Mariotti so we could connect > inexpensive 3 channel station to Earthworms. Joachim Saul of GFZ is > getting that going. > > Here are some URL for what I have mentioned above. I can send anyone > who want a screen shot of the Swarm GUI. > > Regards, > > Angel > > > > > PARxCH digitizers available from: > www.symres.com Kip there has been very helpful. > > Earthworm is available from: > http://folkworm.ceri.memphis.edu/ew-doc/ > > Seiscomp is available from: > http://www.gfz-potsdam.de/geofon/new/scp.html > > Swarm is available from: > http://www.stanford.edu/~dcerv/swarm/ > > Winston: > http://www.avo.alaska.edu/Software/ > > Swarm and Winston are beta and Earthworm is 6.2 with 6.3 coming out > soon. Seiscomp is work in progress. > > > > > > > > > > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Problem sending event files From: Bobhelenmcclure@....... Date: Sat, 25 Jun 2005 21:23:58 EDT On Thu, 23 Jun 2005, Robert Laney wrote: >I have run into a problem trying to submit an email of event files via AOL.< Hi Bob, Have you tried making up your own email with the event file attached, rather than than trying to send it via WinQuake? I am an AOL subscriber and have no problems sending that way. About a month ago, I experienced difficulties, but Larry found and fixed the problem. I have never attempted to send files from WinQuake itself. You cannot send more than one file at a time!!! AOL always makes a ZIP of multiple attachments, and seismicnet's server does not accept ZIP files. Regards, Bob McClure Locust Valley, NY, USA 40.882N 73.582W On Thu, 23 Jun 2005, Robert Laney w= rote:
    >I have run into a problem trying to submit an email of event files via A= OL.<

    Hi Bob,

      Have you tried making up your own email with the event file attached,= rather than than trying to send it via WinQuake? I am an AOL subscriber and= have no problems sending that way. About a month ago, I experienced difficu= lties, but Larry found and fixed the problem. I have never attempted to send= files from WinQuake itself.

      You cannot send more than one file at a time!!!  AOL always make= s a ZIP of multiple attachments, and seismicnet's server does not accept ZIP= files.

    Regards,

    Bob McClure
    Locust Valley, NY, USA
    40.882N  73.582W
    Subject: Re[2]: Earthworm, Winston, Swarm, PAR1CH From: Angel sismos@.............. Date: Sat, 25 Jun 2005 20:41:08 -0500 Hi Jim, That really would be great, but not at this point as far as I know. angel > Can you configure swarm to utilize Larry's WinSDR and/or Winquake output? > Jim __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: earth tide tables From: "Tom Schmitt" tschmitt@.............. Date: Sun, 26 Jun 2005 13:34:37 -0400 I think that if you go to a basic geophysics book the sections on gravimetery will have some formulas for the attraction of the moon and sun as a function of latitude, year, time of day etc. One has to correct for those when doing a gravity survey. The second order effects are harder to get and very, very small. Absolute gravity measurements used to be made with pendulums. I do not know how they do them now. I think they had to stay on station a long time, like longer than the variation due to sun moon interactions, however a good geophysics or geodesy book will have that in it also. Tom Schmitt -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of BOB BARNS Sent: Friday, June 24, 2005 8:06 PM To: psn mail Subject: earth tide tables Hi gang, A friend has several high precision pendulum clocks (and has built 2 others). He asked me to inquire of this list about where to get tables of earth tide data so that he can compare changes in the local value of g to daily variations of period which he sees in his clocks. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: earth tide tables From: ChrisAtUpw@....... Date: Sun, 26 Jun 2005 22:49:23 EDT In a message dated 26/06/2005, tschmitt@.............. writes: I think that if you go to a basic geophysics book the sections on gravimetery will have some formulas for the attraction of the moon and sun as a function of latitude, year, time of day etc. One has to correct for those when doing a gravity survey. The second order effects are harder to get and very, very small. There is quite a bit of information on gravimeters at _http://www.ecgs.lu/_ (http://www.ecgs.lu/) The Earth tides give angular changes of about 50 to 100 nano radians. Absolute gravity measurements used to be made with pendulums. I do not know how they do them now. I think they had to stay on station a long time, like longer than the variation due to sun moon interactions, however a good geophysics or geodesy book will have that in it also. The geo survey type used twin pendulums of fused quartz and optical readout. I have given a few more references at _http://www.seismicnet.com/psnlist/030520_101305_1.html_ (http://www.seismicnet.com/psnlist/030520_101305_1.html) Earth tides are more easily measured using large water tiltmeters. Nicolas d'Oreye's Thesis using measurements at Walferdange is on line at _http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-10172003-155611/_ (http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-10172003-155 611/) It is listed as a series of chapters. If your French is a bit rusty, you might want to access the sections using babelfish _http://babelfish.altavista.com/_ (http://babelfish.altavista.com/) Regards, Chris Chapman
    In a message dated 26/06/2005, tschmitt@.............. writes:
    <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I think=20 that if you go to a basic geophysics book the sections on
    gravimetery w= ill=20 have some formulas for the attraction of the moon and
    sun as a function= of=20 latitude, year,  time of day etc. One has to
    correct for thos= e=20 when doing a gravity survey. The second order
    effects are harder t= o=20 get and very, very small.
        There is quite a bit of information on gravimet= ers=20 at http://www.ecgs.lu/ The Earth ti= des=20 give angular changes of about 50 to 100 nano radians.
    <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Absolute=20 gravity measurements used to be made with pendulums.  I do not
    kno= w=20 how they do them now.  I think they had to stay on station a=20 long
    time,  like longer than the variation due to sun moon=20 interactions,
    however a good geophysics or geodesy book will have that=20= in=20 it also. 
        The geo survey type used twin pendulums of fuse= d=20 quartz and optical readout. I have given a few more references at http://www.s= eismicnet.com/psnlist/030520_101305_1.html
     
        Earth tides are more easily measured using larg= e=20 water tiltmeters. Nicolas d'Oreye's Thesis using measurements at Walferdange= is=20 on line at http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/Be= lnUcetd-10172003-155611/ It=20 is listed as a series of chapters. If your French is a bit rusty, you might=20= want=20 to access the sections using babelfish http://babelfish.altavista.com/=
     
        Regards,
     
        Chris Chapman
    Subject: RE: earth tide tables From: "Tom Schmitt" tschmitt@.............. Date: Mon, 27 Jun 2005 08:59:20 -0400 Nice link on the tiltmeter! I will try to get through the French later. Tom Schmitt -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Sunday, June 26, 2005 10:49 PM To: psn-l@.............. Subject: Re: earth tide tables In a message dated 26/06/2005, tschmitt@.............. writes: I think that if you go to a basic geophysics book the sections on gravimetery will have some formulas for the attraction of the moon and sun as a function of latitude, year, time of day etc. One has to correct for those when doing a gravity survey. The second order effects are harder to get and very, very small. There is quite a bit of information on gravimeters at http://www.ecgs.lu/ The Earth tides give angular changes of about 50 to 100 nano radians. Absolute gravity measurements used to be made with pendulums. I do not know how they do them now. I think they had to stay on station a long time, like longer than the variation due to sun moon interactions, however a good geophysics or geodesy book will have that in it also. The geo survey type used twin pendulums of fused quartz and optical readout. I have given a few more references at http://www.seismicnet.com/psnlist/030520_101305_1.html Earth tides are more easily measured using large water tiltmeters. Nicolas d'Oreye's Thesis using measurements at Walferdange is on line at http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-10172 003-155611/ It is listed as a series of chapters. If your French is a bit rusty, you might want to access the sections using babelfish http://babelfish.altavista.com/ Regards, Chris Chapman

    Nice link on the = tiltmeter!  I will try to get through the French later.

     

     

     

    Tom Schmitt

     

    -----Original = Message-----
    From: = psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@.......
    Sent: Sunday, June 26, = 2005 10:49 PM
    To: = psn-l@..............
    Subject: Re: earth tide = tables

     

    In a message dated 26/06/2005, tschmitt@.............. = writes:

    I think that if you go to a basic geophysics book the sections on
    gravimetery will have some formulas for the attraction of the moon = and
    sun as a function of latitude, year,  time of day etc. One has = to
    correct for those when doing a gravity survey. The second order
    effects are harder to get and very, very small.

      &nbs= p; There is quite a bit of information on gravimeters at http://www.ecgs.lu/ The Earth tides give angular changes of about 50 to 100 nano radians. =

    Absolute gravity measurements used to be made with pendulums.  I do not
    know how they do them now.  I think they had to stay on station a = long
    time,  like longer than the variation due to sun moon = interactions,
    however a good geophysics or geodesy book will have that in it = also. 

      &nbs= p; The geo survey type used twin pendulums of fused quartz and optical readout. = I have given a few more references at http://ww= w.seismicnet.com/psnlist/030520_101305_1.html

     

      &nbs= p; Earth tides are more easily measured using large water tiltmeters. Nicolas = d'Oreye's Thesis using measurements at Walferdange is on line at http://edoc.bib.ucl.ac.be:81/ETD-db/collection/availa= ble/BelnUcetd-10172003-155611/ It is listed as a series of chapters. If your French is a bit rusty, you = might want to access the sections using babelfish http://babelfish.altavista.com/<= /a>

     

      &nbs= p; Regards,

     

      &nbs= p; Chris Chapman

    Subject: copper weight From: ian ian@........... Date: Mon, 27 Jun 2005 22:12:27 +0100 has anyone tried copper instead of lead for the weight on a Lehman? The idea being that it could also be used for magnetic damping. Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: copper weight From: Jack Ivey ivey@.......... Date: Mon, 27 Jun 2005 19:20:01 -0400 Yep, I use a piece of 1/4"x2"x3" piece and it worked fine for both mass and damping. For a damping magnet I used a 1/2"x1" long cylindrical neodymium magnet. The seismo isn't a Lehman exactly, but a garden-gate horizontal made of aluminum angle. The Lehman would probably require a bit heavier chunk. I also used a small piece of 1/4" copper for the mass/damper in a vertical pendulum (similar to S-G). Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ian Sent: Monday, June 27, 2005 5:12 PM To: psn-l@.............. Subject: copper weight has anyone tried copper instead of lead for the weight on a Lehman? The idea being that it could also be used for magnetic damping. Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: copper weight From: John Popelish jpopelish@........ Date: Mon, 27 Jun 2005 20:21:09 -0400 ian wrote: > has anyone tried copper instead of lead for the weight on a Lehman? The > idea being that it could also be used for magnetic damping. Either can be used for magnetic damping. Lead's advantage is its density at 1.27 times copper's. It is also easier to cast into a compact lump that is the right shape to be attached to a pendulum. The higher conductivity of copper (13 times that of lead) increases its damping effect for a given magnetic field strength, but lead is no insulator. A good compromise is to use a block of lead (for mass) attached to a thin sheet of copper or aluminum (1.6 times higher resistivity than copper). The thinness of the sheet allows you to get a pair of magnets closer together on opposite sides of it, increasing the magnetic field strength. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: copper weight From: ChrisAtUpw@....... Date: Mon, 27 Jun 2005 22:52:23 EDT In a message dated 28/06/2005, jpopelish@........ writes: ian wrote: > has anyone tried copper instead of lead for the weight on a Lehman? The > idea being that it could also be used for magnetic damping. Either can be used for magnetic damping. Lead's advantage is its density at 1.27 times copper's. Hi John, You can use a flat horizontal 1/4" thick Cu plate for the mass and the damping plate quite OK. Trying to use sheet lead for damping is likely to be less successful - the resistivity is a bit too high. You need to keep the edges of the Cu plate well away from the edges of the magnetic field - to avoid small magnetic forces. Brass is another good material for making mass weights, but it is not much use for damping. Brass is about 8.6 gm / ml, Cu is 8.9, Lead is 11.3. The higher conductivity of copper (13 times that of lead) increases its damping effect for a given magnetic field strength. A good compromise is to use a block of lead (for mass) attached to a thin sheet of copper or aluminum (1.6 times higher resistivity than copper). The thinness of the sheet allows you to get a pair of magnets closer together on opposite sides of it, increasing the magnetic field strength. If you use a N + S pair of rectangular 1" x 1/2" x 1/4" NdFeB magnets on two opposed 1/4" thick soft iron backing plates, you should get ample damping. You hold the iron plates apart at a set distance using 1/4" mild steel bolts and nuts. I use 3.5" long by 2" wide by 1/4" bright rolled mild steel strip. The longer the set period of the Lehman, the less damping you need. Regards, Chris Chapman
    In a message dated 28/06/2005, jpopelish@........ writes:
    <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>ian=20 wrote:
    > has anyone tried copper instead of lead for the weight on a= =20 Lehman?  The
    > idea being that it could also be used for magne= tic=20 damping.

    Either can be used for magnetic damping.  Lead's=20 advantage is its
    density at 1.27 times=20 copper's. 
    Hi John,
     
        You can use a flat horizontal 1/4" thick Cu pla= te=20 for the mass and the damping plate quite OK. Trying to use sheet lead f= or=20 damping is likely to be less successful - the resistivity is a bit too high.= You=20 need to keep the edges of the Cu plate well away from the edges of the magne= tic=20 field - to avoid small magnetic forces.
        Brass is another good material for making mass=20 weights, but it is not much use for damping. Brass is about 8.6 gm / ml= , Cu=20 is 8.9, Lead is 11.3.=20
     
    <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 higher conductivity of copper (13 times that of lead) increases its dampin= g=20 effect for a given magnetic field strength. A good compromise is to use a=20 block of lead (for mass) attached to a thin sheet of copper or aluminum (1= ..6=20 times higher resistivity than copper).  The thinness of the sheet all= ows=20 you to get a pair of magnets closer together on opposite sides of it,=20 increasing the magnetic field strength.
        If you use a N + S pair of rectangular 1"=20= x=20 1/2" x 1/4" NdFeB magnets on two opposed 1/4" thick soft iron backing=20 plates, you should get ample damping. You hold the iron plates apart at a se= t=20 distance using 1/4" mild steel bolts and nuts. I use 3.5" long by 2" wide by= =20 1/4" bright rolled mild steel strip. The longer the set period of the Lehman= ,=20 the less damping you need.
     
          Regards,
     
        Chris Chapman
    Subject: Real time FFT From: Richard Webb dwebb002@............. Date: Tue, 28 Jun 2005 11:17:47 -0400 Hi, I was wondering if it is possible to do FFTs on the fly as a means of differentiating earthquakes from environmental noise (cars, explosions, wind, etc.). From what I have read, their FFT signatures for these items are quite different. Can it be done with WINSDR or other software that can be used in conjunction with WINSDR. Dick __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: copper weight From: John Popelish jpopelish@........ Date: Tue, 28 Jun 2005 20:06:40 -0400 ChrisAtUpw@....... wrote: (snip) > You need to keep the edges of the Cu plate well away from the edges > of the magnetic field - to avoid small magnetic forces. This is a very good point. The eddy currents circulate around the spot where the field lines pass through the surface of the metal, when there is movement. You need some metal outside the concentrated area of field to make best use of the magnetic field. You can always back the magnets away from the metal to weaken the field if you have too much damping. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Real time FFT From: Larry Cochrane lcochrane@.............. Date: Tue, 28 Jun 2005 17:52:10 -0700 Hi Dick, The current version of WinSDR (http://www.seismicnet.com/winsdr/betarelease.html) does an FFT on the incoming data from the A/D board to detect teleseismic events. It seems to work OK most of the time. Regards, Larry Cochrane Redwood City, PSN Richard Webb wrote: > Hi, > > I was wondering if it is possible to do FFTs on the fly as a means of > differentiating earthquakes from environmental noise (cars, explosions, > wind, etc.). From what I have read, their FFT signatures for these > items are quite different. Can it be done with WINSDR or other software > that can be used in conjunction with WINSDR. > > Dick > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Real time FFT From: "Timothy Carpenter" GeoDynamics@....... Date: Tue, 28 Jun 2005 23:53:28 -0400 Larry, Can you steer me to some references in the use of FFT results for identifying and triggering on teleseismic and other events? I scanned through the on-line info for WinSDR 2.0.8 B4 but couldn't find any clues about where to look next. I have not downloaded WinSDR -- if there is guidance w/r FFTs embedded in the pgm, let me know and I'll download it. = Regards, -Tim- Timothy Carpenter, P.E., Pres., GeoDynamics Consultants, Inc. 5043 Whitlow Ct. Commerce Twp., Mi 48382 248-363-4529 (voice & fax) 248-766-1629 (cell) geodynamics@........... (primary) geodynamics@....... (secondary) =A0 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Larry Cochrane Sent: Tuesday, June 28, 2005 8:52 PM To: psn-l@.............. Subject: Re: Real time FFT Hi Dick, The current version of WinSDR (http://www.seismicnet.com/winsdr/betarelease.html)=20 does an FFT on the incoming data from the A/D board to detect = teleseismic events. It=20 seems to work OK most of the time. Regards, Larry Cochrane Redwood City, PSN Richard Webb wrote: > Hi, >=20 > I was wondering if it is possible to do FFTs on the fly as a means of=20 > differentiating earthquakes from environmental noise (cars, = explosions,=20 > wind, etc.). From what I have read, their FFT signatures for these=20 > items are quite different. Can it be done with WINSDR or other = software=20 > that can be used in conjunction with WINSDR. >=20 > Dick > __________________________________________________________ >=20 > Public Seismic Network Mailing List (PSN-L) >=20 > To leave this list email PSN-L-REQUEST@.............. with=20 > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. >=20 >=20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Real time FFT From: "Timothy Carpenter" GeoDynamics@....... Date: Tue, 28 Jun 2005 23:59:54 -0400 Larry, Well, color my face red. Belay that last request -- after I sent the message, I "Googled" for "FFT Teleseismic Trigger" and got plenty of = reading material. Of course the first note was from PSN in August, 2000. -Tim- Timothy Carpenter, P.E., Pres., GeoDynamics Consultants, Inc. 5043 Whitlow Ct. Commerce Twp., Mi 48382 248-363-4529 (voice & fax) 248-766-1629 (cell) geodynamics@........... (primary) geodynamics@....... (secondary) =A0 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Larry Cochrane Sent: Tuesday, June 28, 2005 8:52 PM To: psn-l@.............. Subject: Re: Real time FFT Hi Dick, The current version of WinSDR (http://www.seismicnet.com/winsdr/betarelease.html)=20 does an FFT on the incoming data from the A/D board to detect = teleseismic events. It=20 seems to work OK most of the time. Regards, Larry Cochrane Redwood City, PSN Richard Webb wrote: > Hi, >=20 > I was wondering if it is possible to do FFTs on the fly as a means of=20 > differentiating earthquakes from environmental noise (cars, = explosions,=20 > wind, etc.). From what I have read, their FFT signatures for these=20 > items are quite different. Can it be done with WINSDR or other = software=20 > that can be used in conjunction with WINSDR. >=20 > Dick > __________________________________________________________ >=20 > Public Seismic Network Mailing List (PSN-L) >=20 > To leave this list email PSN-L-REQUEST@.............. with=20 > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. >=20 >=20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L)