We were discussing sound cards and I was reject= ing=20 this as impractical for seismic purposes. The data files are massive and I=20 haven't found a way of using the 24 bit soundcard ADC for 20 sps sampling.

Chuck a bit of cash at it and get rid of the yo= ur=20 problems? Larry sells a fairly good 8 channel serial board, which you can us= e=20 with a GPS receiver.

If you want to play, fine. If you want to work,= get=20 rid of problems that you do not need to have.

Just what rate of water rise do you get al= ong=20 the Red river?? Even for marine waves, 20 sps is adequate and most geologica= l=20 systems will go to 100sps, some even more.

>> A GPS will give you the best time s= tamp=20 you could ask for some even have a 100 kHz clock as well a 1 second pulse th= at=20 are linked to GPS clocks. They can be used to phase lock frequency sources t= o=20 for super accurate osillators.

I am NOT asking for the best system, just one t= hat=20 relatively inexpensive, low power and ADEQUATE for my purposes.

I use VLF timing signals. You can get relativel= y=20 inexpensive receiver boards with a ferrite aerial: or gut a radio clock. You= get=20 about 10 mS + the transit time. The only folks who need it more accurate mon= itor=20 volcanoes of do reflection seismometry. I have been all along this road. I w= ould=20 be great if Larry would fit the software to decode WWVB directly, but he=20 seems concentrate on GPS. GPS is power hungry and needs a clear l= ine=20 of sight to satellites; 60 KHz VLF radio is low power and can be used most=20 anywere. I can use it where I can't get MW radio, even underground. Just kee= p it=20 away from striplights, radio transmitters, TVs and computer monitors. I have= =20 used it underground near radio and TV transmitters - find a nice hole and bu= ry=20 it to screen it! It is no accident that submarine communications use=20 the VLF range of frequencies.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If you=20 are not interested in 1 to 20 Hz signals sound cards are pretty good tools= .. If=20 you are really serious about low frequencies and accurate timing Windows p= oses=20 a lot of problems.

0 to 10 Hz is my range of interest. I want abou= t=20 +/-0.1 sec accuracy, 24 hrs / day. This is why I use an ADC which has it's o= wn=20 on board timing and correction. The data goes to the hard disk with a time s= tamp=20 regardless of the rubbish timing on the operating system.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>First=20 Windows is an event driven operating system and there is no assurance when= a=20 program will run. The sound card gets around that but you have to put a ch= irp=20 on the signal to synchronize it with time you can depend on the computer c= lock=20 or the RS232 port.

Can you say that again please? I don't quite=20 understand.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Having=20 worked with embedded systems for the last 20 years I would choose a real t= ime=20 computer. There are real time versions of Linux but I think that's over ki= ll=20 for dataloging geophones.

You have the real and the software clocks on=20 computer boards. You used to be able to get 4.194 MHz AT crystal clocks on=20 computers, which could be made moderately reliable. All the boards that I ha= ve=20 seen recently use 32 KHz crystals which appear to be rejects from clock=20 manufacturers. A random error of 20 sec to 2 min a day is what I call utter=20 ****. If you had a quartz watch which was that bad, you would take it back t= o=20 the shop and demand your money back.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>A GPS=20 for a time base, a good a/d converter and fast microcontroler would be the= way=20 I would do it. I am working with a very fast board 60 MHz with 4 10 bit A/= D=20 channels

Does 10 bits give you enough resolution, taking= =20 into account sensor noise? The Dataq $25 starter ADCs give you 4 Channels at= 240=20 sps total - 60 sps / channel.

I can't figure out at the moment why you wo= uld=20 need a high monitoring rate for looking at water levels?

Regards,

Chris Chapman

Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Thu, 21 Jul 2005 01:03:18 -0500 ChrisAtUpw@....... wrote: > In a message dated 20/07/2005, gcouger@.......... writes: > > Chris, > > Out of sequence and possible not on subject but it has some thoughts > on timing that are important. I must have come in the middle and > don't understand your set up. I thought you were recording data to > disk with a computer sound card. > > I am working on a seismometer that records several seismometers at > one time in the 0-50 HZ range on the two channels of a sound card > for imaging shallow aquifers looking for larger gravel to find > better water well in a shallow aquifer along Red River > between Oklahoma and Texas so I can afford to put in irrigation. > > I have probably imposed my project on yours without realizing it. > > Hi Gordon, > > We were discussing sound cards and I was rejecting this as > impractical for seismic purposes. The data files are massive and I > haven't found a way of using the 24 bit soundcard ADC for 20 sps sampling. > > Chuck a bit of cash at it and get rid of the your problems? Larry > sells a fairly good 8 channel serial board, which you can use with a GPS > receiver. > If you want to play, fine. If you want to work, get rid of problems > that you do not need to have. > Just what rate of water rise do you get along the Red river?? Even > for marine waves, 20 sps is adequate and most geological systems will go > to 100sps, some even more. > > >> A GPS will give you the best time stamp you could ask for some > even have a 100 kHz clock as well a 1 second pulse that are linked to > GPS clocks. They can be used to phase lock frequency sources to for > super accurate osillators. > > I am NOT asking for the best system, just one that relatively > inexpensive, low power and ADEQUATE for my purposes. > I use VLF timing signals. You can get relatively inexpensive > receiver boards with a ferrite aerial: or gut a radio clock. You get > about 10 mS + the transit time. The only folks who need it more accurate > monitor volcanoes of do reflection seismometry. I have been all along > this road. I would be great if Larry would fit the software to decode > WWVB directly, but he seems concentrate on GPS. GPS is power hungry and > needs a clear line of sight to satellites; 60 KHz VLF radio is low power > and can be used most anywere. I can use it where I can't get MW radio, > even underground. Just keep it away from striplights, radio > transmitters, TVs and computer monitors. I have used it underground near > radio and TV transmitters - find a nice hole and bury it to screen it! > It is no accident that submarine communications use the VLF range of > frequencies. > > If you are not interested in 1 to 20 Hz signals sound cards are > pretty good tools. If you are really serious about low frequencies > and accurate timing Windows poses a lot of problems. > > 0 to 10 Hz is my range of interest. I want about +/-0.1 sec > accuracy, 24 hrs / day. This is why I use an ADC which has it's own on > board timing and correction. The data goes to the hard disk with a time > stamp regardless of the rubbish timing on the operating system. > > First Windows is an event driven operating system and there is no > assurance when a program will run. The sound card gets around that > but you have to put a chirp on the signal to synchronize it with > time you can depend on the computer clock or the RS232 port. > > Can you say that again please? I don't quite understand. > > Having worked with embedded systems for the last 20 years I would > choose a real time computer. There are real time versions of Linux > but I think that's over kill for dataloging geophones. > > You have the real and the software clocks on computer boards. You > used to be able to get 4.194 MHz AT crystal clocks on computers, which > could be made moderately reliable. All the boards that I have seen > recently use 32 KHz crystals which appear to be rejects from clock > manufacturers. A random error of 20 sec to 2 min a day is what I call > utter ****. If you had a quartz watch which was that bad, you would take > it back to the shop and demand your money back. > > A GPS for a time base, a good a/d converter and fast microcontroler > would be the way I would do it. I am working with a very fast board > 60 MHz with 4 10 bit A/D channels > > Does 10 bits give you enough resolution, taking into account sensor > noise? The Dataq $25 starter ADCs give you 4 Channels at 240 sps total - > 60 sps / channel. > I can't figure out at the moment why you would need a high > monitoring rate for looking at water levels? > > Regards, > > Chris Chapman > Chris, I am not looking for water levels I putting out sensors and making a shock moving over and making another shock ...... and another shock and resetting the sensors and doing it over again to do a seismic study of the aquifer of the water bearing sand and 30 feet down. I need a post process GPS signal to know where I am I might as well use the time spruce on it. Almost everything I work with has a GPS. I did the first vehicle units for www.ipsolutionsinc.com and all the software for spryer in http://www.ppi-far.org/ppiweb/bcrops.nsf/$webindex/6041B8CEFFC83068852568F10056A8F7/$file/97-4p15.pdf!open I agree they are power hogs and take a lot of resources for time for seismic senors that VLF will do just as well as GPS. I have seen jitter on VLF from WWV in a really bad magnetic storm but not as often as I have lost lock with the GPS. If you want to time sync a signal on a sound card you can depend on windows for time. It is too uncertain when the windows routine will time stamp it. Windows can't be made work in real time. If you want to record 0 to 20 Hz signals on a sound card a mixer and local oscillator at 500 Hz will move the 0 to 20 Hz to 500 to 520 and the inverse of it to 480 to 500. You can use DSP to get the signal back from either one. Ten bits is enough for most situations in vehicles any more is lost in the noise of the vehicle. In the case of seismometer in an open field a more sensitive A/D could be used. Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 08:33:42 EDT In a message dated 21/07/2005, gcouger@.......... writes: Chris, I am not looking for water levels I putting out sensors and making a shock moving over and making another shock ....I need a post process GPS signal to know where I am I might as well use the time spruce on it. Hi Gordon, I understand now. We used chains of hf geophones and a pneumatic hammer.... Sure you need te position accurately as well. Do you use relative GPS to give you accuracies down to a few cm? Almost everything I work with has a GPS. I did the first vehicle units for www.ipsolutionsinc.com and all the software for spryer in http://www.ppi-far.org/ppiweb/bcrops.nsf/$webindex/6041B8CEFFC83068852568F1005 6A8F7/$file/97-4p15.pdf!open Interesting, but availablily depends on the roots being able to find nutrients and hence on the rainfall & intensity. It probably would not work too well for things like moss and poor land grasses. The grab every nutrient molecule going and store them. This was the problem in Finland after the Chernobyl nuclear disaster. The grasses and moss which fed the reindeer heards soaked up most of the radioactivity. I agree they are power hogs and take a lot of resources for time for seismic senors that VLF will do just as well as GPS. I have seen jitter on VLF from WWV in a really bad magnetic storm but not as often as I have lost lock with the GPS. I don't get this problem at all often. The computer looks for an interference free minute every half hour and then adjusts the precision crystal oscillator offset on the 59 mean pulses. The drift is initially set at less than 5 ppm and can be maintained down parts in 10^8 If you want to time sync a signal on a sound card you can depend on windows for time. It is too uncertain when the windows routine will time stamp it. Windows can't be made work in real time. Where are you getting your time stamp from? I definitely can't rely on either the software or the hardware clocks on the board. If you want to record 0 to 20 Hz signals on a sound card a mixer and local oscillator at 500 Hz will move the 0 to 20 Hz to 500 to 520 and the inverse of it to 480 to 500. You can use DSP to get the signal back from either one. Ten bits is enough for most situations in vehicles any more is lost in the noise of the vehicle. In the case of seismometer in an open field a more sensitive A/D could be used. Regards, Chris Chapman

In a message dated 21/07/2005, gcouger@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Chris,

I am not looking for water levels I putting out sen= sors=20 and making a shock moving over and making another shock ....I need a post=20 process GPS signal to know where
I am I might as well use the time spr= uce=20 on it.

Hi Gordon,

I understand now. We used chains of hf geophone= s=20 and a pneumatic hammer.... Sure you need te position accurately as well. Do=20= you=20 use relative GPS to give you accuracies down to a few cm?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Almost=20 everything I work with has a GPS. I did the first vehicle units for=20 www.ipsolutionsinc.com and all the software for spryer in=20
http://www.ppi-far.org/ppiweb/bcrops.nsf/$webindex/6041B8CEFFC83068852= 568F10056A8F7/$file/97-4p15.pdf!open

Interesting, but availablily depends on the roo= ts=20 being able to find nutrients and hence on the rainfall & intensity. It=20 probably would not work too well for things like moss and poor land grasses.= The=20 grab every nutrient molecule going and store them. This was the problem in=20 Finland after the Chernobyl nuclear disaster. The grasses and moss which fed= the=20 reindeer heards soaked up most of the radioactivity.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I agree=20 they are power hogs and take a lot of resources for time
for seismic=20 senors that VLF will do just as well as GPS. I have
seen jitter on VLF= =20 from WWV in a really bad magnetic storm but
not as often as I have los= t=20 lock with the GPS.

I don't get this problem at all often. The comp= uter=20 looks for an interference free minute every half hour and then adjusts the=20 precision crystal oscillator offset on the 59 mean pulses. The drift is=20 initially set at less than 5 ppm and can be maintained down parts in 10^8 <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If you=20 want to time sync a signal on a sound card you can depend
on windows f= or=20 time. It is too uncertain when the windows
routine will time stamp it.= =20 Windows can't be made work in real time.

Where are you getting your time stamp from? = I=20 definitely can't rely on either the software or the hardware clocks on the=20 board.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If you=20 want to record 0 to 20 Hz signals on a sound card a mixer and local oscill= ator=20 at 500 Hz will move the 0 to 20 Hz to 500 to 520 and the inverse of it to=20= 480=20 to 500. You can use DSP to get the signal back from either one.

Ten= =20 bits is enough for most situations in vehicles any more is lost in the noi= se=20 of the vehicle. In the case of seismometer in an open field a more sensiti= ve=20 A/D could be used.

Regards,

Chris Chapman

Subject: RE: Modified sound card and datalogging and geophones From: "Doug Crice" dcrice@............ Date: Thu, 21 Jul 2005 05:48:51 -0700 Snip I am not looking for water levels I putting out sensors and making a shock moving over and making another shock ...... and another shock and resetting the sensors and doing it over again to do a seismic study of the aquifer of the water bearing sand and 30 feet down. I need a post process GPS signal to know where I am I might as well use the time spruce on it. UnSnip This is not earthquake recording, this is exploration seismic. The frequencies you care about will be between 10 and 500 Hz and a perfectly normal sound card will handle these signals. You may need some preamps like you would with a dynamic phonograph cartridge, because the signals from geophones are small. You will need zero time from your shock source (a sledge hammer should be adequate). The best choice is a small, cheap crystal phonograph cartridge taped near the head connected to the second channel. You don't care about absolute time, just time relative to the impact, so forget GPS timing. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 10:06:54 EDT In a message dated 21/07/2005, dcrice@............ writes: This is not earthquake recording, this is exploration seismic. You will need zero time from your shock source (a sledge hammer should be adequate). The best choice is a small, cheap crystal phonograph cartridge taped near the head connected to the second channel. You don't care about absolute time, just time relative to the impact, so forget GPS timing. I have used ordinary 13 mm piezo disks for the hammer sensor, but you do need some sort of voltage limitation to prevent input amplifier protection. The 'glass break' sensors sold for window protection work fine and are maybe less than 1/10 the price of a phono cartridge. You can use biassed current differencing amplifiers to give a ramped gain / time relationship to maintain the reflected signal strength. Regards, Chris Chapman

In a message dated 21/07/2005, dcrice@............ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>This is=20 not earthquake recording, this is exploration seismic.
You will n= eed=20 zero time from your shock source (a sledge hammer should be
adequate).=20= The=20 best choice is a small, cheap crystal phonograph cartridge
taped near t= he=20 head connected to the second channel. You don't care about
absolute tim= e,=20 just time relative to the impact, so forget GPS=20 timing.

I have used ordinary 13 mm piezo disks for the=20 hammer sensor, but you do need some sort of voltage limitation to=20 prevent input amplifier protection. The 'glass break' sensors sold= for=20 window protection work fine and are maybe less than 1/10 the price of a= =20 phono cartridge. You can use biassed current differencing amplifiers to give= a=20 ramped gain / time relationship to maintain the reflected signal strength.

Regards,

Chris Chapman

Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Thu, 21 Jul 2005 13:21:01 -0500 Hi Chris, > > I understand now. We used chains of hf geophones and a pneumatic > hammer.... Sure you need te position accurately as well. Do you use > relative GPS to give you accuracies down to a few cm? I haven't so far. The precision of the seismic data is not that good. But I will leave temporary bench marks I can find. Since it is being farmed no till I can bury a piece of tinfoil and put up a PVC post. If the post gets knocked down a GPS and metal detector will get me back on the spot. The PVC won't hurt any equipment it happens to go through. > > Almost everything I work with has a GPS. I did the first vehicle > units for www.ipsolutionsinc.com and all the software for spryer in > http://www.ppi-far.org/ppiweb/bcrops.nsf/$webindex/6041B8CEFFC83068852568F10056A8F7/$file/97-4p15.pdf!open > > Interesting, but availablily depends on the roots being able to find > nutrients and hence on the rainfall & intensity. It probably would not > work too well for things like moss and poor land grasses. The grab every > nutrient molecule going and store them. This was the problem in Finland > after the Chernobyl nuclear disaster. The grasses and moss which fed the > reindeer heards soaked up most of the radioactivity. It works for anything we have tried it on. It measures the nitrogen in the leaves of the wheat by looking at the ratio of narrow band of red and near infrared light in late winter just before it starts the process of going from vegetative state to a fruiting or grain producing stage. In this case we are adding fertilizer to the soil in the late winter because in the vegetative state wheat uses nitrogen to grow large lush leaves and in the grain producing stage it uses much more of it to make grain and much less to make leaves. Also nitrogen is some what perishable and can leach down below the root zone if there is too much rain or turn into ammonia and escape in atmosphere if water stands on the ground. So it takes less nitrogen to produce a bushel of wheat if it put one in February than if it is put on in the previous September. By putting it down in February or March we can assure that the nitrogen in the root zone where the plant can get it when it can make the most use of it. The fertilizer could just as well be foliar fertilizer that is taken up trough the leaves. In the case of most farm crops that is not an economic option because until you get rain the plant can't benefit from the fertilizer unless the ground is wet enough to take up the fertilizer. We found several strategies that gave more return on the dollar spent on fertilizer, First was to make the nitrogen level in the wheat as near the same everywhere in the field as we could. The generally cut the fertilizer use in half and the dyed didn't change. The next was leave the areas high in nitrogen alone and double up on the low spots. That used the same amount of fertilizer and increased yields 7%. If we added in the historical yield data and added fertilizer to the point that each area had enough nitrogen to yield it full potential we got about 10% increase. I would be surprised it the system if half as could as it could be with smaller sample sizes and more experience. This only works with nutrients such as nitrogen, zinc and few others that can be applied to a growing plant and still benefit it. Other nutrients phosphorus being the most important one need to be applied before the plant spouts and immediately available to the roots. In the case of Chernobyl strontium 90 is metabolized much like phosphorus and cesium is handled like potassium. So after the rain washed the fall out off the worst problme weren't probably seen until the next year and they did make an effort in some areas to deep plow the fall out under below the root zone of the grasses and fertilize with P and K to prevent the grasses from taking up as many radioactive isotopes as they could. That only worked on land that could be plowed and that is not were reindeer generally graze. > > I agree they are power hogs and take a lot of resources for time > for seismic senors that VLF will do just as well as GPS. I have > seen jitter on VLF from WWV in a really bad magnetic storm but > not as often as I have lost lock with the GPS. > > I don't get this problem at all often. The computer looks for an > interference free minute every half hour and then adjusts the precision > crystal oscillator offset on the 59 mean pulses. The drift is initially > set at less than 5 ppm and can be maintained down parts in 10^8 The problem is not very common it takes a really big magnetic storm to cause it an they don't happen often. The 5 volt one Hz signal off a Rockwell Jupiter or many other GPS receivers makes an ideal heart beat for a clock for an microcomputer. If you need finer granularity a divider or phased locked loop on the 100 kHz output is a bit harder to build but is easier than a VLF radio. Both your way with WWV VLF and a GPS have their place. But with GPS receivers with one second clock pins selling for 25 to 50 bucks new in the box it is hard to see why any one would go to the effort to use VLF unless there were problems that precluded using a GPS. Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Thu, 21 Jul 2005 13:52:05 -0500 Hi Doug > Snip > UnSnip > > This is not earthquake recording, this is exploration seismic. The > frequencies you care about will be between 10 and 500 Hz and a perfectly > normal sound card will handle these signals. You may need some preamps like > you would with a dynamic phonograph cartridge, because the signals from > geophones are small. > > You will need zero time from your shock source (a sledge hammer should be > adequate). The best choice is a small, cheap crystal phonograph cartridge > taped near the head connected to the second channel. You don't care about > absolute time, just time relative to the impact, so forget GPS timing. > I am using standard seismic sensors and I will probably use a ..22 or .38 fired into the ground or a slide hammer lifted up by a blank cartridge. My sledge hammer swinging days have been over for 20 years due to multiple sclerosis. I think I need a better clock than the computer has for relative measuring and I plan to divide down the 100 KHZ clock on the GPS to 1000 HZ and put on each channel of the sound card for a time base and reference. Each sensor will modulate an oscillator at a different frequency and all will be mixed together and recorded on the sound card and the 1000 HZ signal will be used to lock on to decoded the others as well as a time base that is automatically generated in the decoding process for each sensor. There is just too much jitter in everthing I have tested in windows to trust it to keep time even on a the sound card that is supposed to run in real time. There also has to be some point to referenced everthing from in both time and frequency. Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Modified sound card and datalogging and geophones From: "Doug Crice" dcrice@............ Date: Thu, 21 Jul 2005 12:21:30 -0700 > Snip I am using standard seismic sensors and I will probably use a .22 or .38 fired into the ground or a slide hammer lifted up by a blank cartridge. = My sledge hammer swinging days have been over for 20 years due to multiple sclerosis. > unsnip Shooting bullets into the ground is not the best energy source; most of = the energy goes into plastic deformation instead of elastic waves. There = was a source made with an 8-gague kiln gun some years ago that generated a lot = of sound and fury, but barely kept up with a sledgehammer except when fired into saturated material.=20 The best gun-like source is the buffalo gun aka "in hole shotgun". You = take a 3/4-inch pipe about 4 feet long and screw a coupling on the end big = enough to hold a shotgun shell. You auger a hole in the ground and stick the = end with the shell down a foot or more. Then you drop a pointed rod down = the pipe to detonate the shell. The shell goes off underground and much = more of the energy is coupled to the soil. It works about as well with blanks = as with loaded shells. Search for in-hole shotgun source on the web and you will find some papers. The most descriptive here http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=3Dnormal&id=3D= GPYSA70 00052000007000985000001&idtype=3Dcvips&gifs=3Dyes There is a commercial version called the Betsy Seisgun, if you search = there you can see pictures of it, but the pipe version works just as well.=20 Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 =20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Thu, 21 Jul 2005 17:39:27 -0500 Doug Crice wrote: >>Snip > > > I am using standard seismic sensors and I will probably use a .22 or .38 > fired into the ground or a slide hammer lifted up by a blank cartridge. My > sledge hammer swinging days have been over for 20 years due to multiple > sclerosis. > > >>unsnip > > > Shooting bullets into the ground is not the best energy source; most of the > energy goes into plastic deformation instead of elastic waves. There was a > source made with an 8-gague kiln gun some years ago that generated a lot of > sound and fury, but barely kept up with a sledgehammer except when fired > into saturated material. > > The best gun-like source is the buffalo gun aka "in hole shotgun". You take > a 3/4-inch pipe about 4 feet long and screw a coupling on the end big enough > to hold a shotgun shell. You auger a hole in the ground and stick the end > with the shell down a foot or more. Then you drop a pointed rod down the > pipe to detonate the shell. The shell goes off underground and much more of > the energy is coupled to the soil. It works about as well with blanks as > with loaded shells. Search for in-hole shotgun source on the web and you > will find some papers. The most descriptive here > http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=GPYSA70 > 00052000007000985000001&idtype=cvips&gifs=yes > > There is a commercial version called the Betsy Seisgun, if you search there > you can see pictures of it, but the pipe version works just as well. > > Doug Crice http://www.geostuff.com > Wireless Seismic http://www.wirelessSeismic.com > 12996 Somerset Drive phone 1-530-274-4445 > Grass Valley, CA 95945 USA fax 1-530-274-4446 > Doug, I know a gun fired in the ground is not a good source and that's why I included a drop hammer lifted by a bank and dropped back on the rod that is attached to a steel plate that sets on the ground. I may have to use a propane to lift the slide over the piston instead of a blank shot gun shell, This fall when it cools off I will see what kind of hammer I need. Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Modified sound card and datalogging and geophones From: "Doug Crice" dcrice@............ Date: Thu, 21 Jul 2005 16:01:54 -0700 For as long as I have been in seismic, people have been trying to build = a good energy source for engineering seismic studies. Let me define such = a device for you experimenters out there. 1) A person ought to be able to carry it around 2) It needs reasonably high frequency output (ping instead of thunk) 3) Build it for $1000 or even $2000 in lots of 10 units, using new commercially available and machined parts. 4) It should be safe, even when used by students 5) There should be no significant regulatory issues (a problem with dynamite, the perfect source) 6) Operating supplies available in third world countries. 7) And last but not least, it needs to work better than a sledgehammer = used with a seismograph that can stack multiple impacts. The in-hole shotgun comes close, but it is possible to shoot yourself in = the foot, blow your hand off, and in one case, blow your brains out. The associated liability prevents any real company from producing the = device. Even if you made it impossible to accidentally hurt yourself, under our = tort system, you would still be liable for intentional injuries. Geostuff will be happy to sell the device using our worldwide network of contacts, assuming it works and is reliable. Mechanical things tend to = self destruct. =20 Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 =20 I know a gun fired in the ground is not a good source and that's=20 why I included a drop hammer lifted by a bank and dropped back=20 on the rod that is attached to a steel plate that sets on the=20 ground. I may have to use a propane to lift the slide over the=20 piston instead of a blank shot gun shell, __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 19:22:06 EDT In a message dated 22/07/2005, dcrice@............ writes: 7) And last but not least, it needs to work better than a sledgehammer used with a seismograph that can stack multiple impacts. Hi Doug, This may be a bit ''off the wall'', but there is another way of looking at the problem. Can we design a better type of sledge hammer + plate / falling weight? Regards, Chris Chapman

In a message dated 22/07/2005, dcrice@............ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>7) And=20 last but not least, it needs to work better than a sledgehammer used
wi= th a=20 seismograph that can stack multiple impacts.

Hi Doug,

This may be a bit ''off the wall'', but there i= s=20 another way of looking at the problem.

Can we design a better type of sledge hammer +=20 plate / falling weight?

Regards,

Chris Chapman

Subject: RE: Modified sound card and datalogging and geophones From: "Doug Crice" dcrice@............ Date: Thu, 21 Jul 2005 16:47:11 -0700 A sledgehammer is operated by swinging it through about a 250 degree = arc, presumably by a muscular associate. If you were to replace it with a = weight drop, you would need to drop it many meters to approximate this amount = of energy. Thus, your weight needs to be accelerated somehow. There are = units that attach to vehicles with large rubber bands. They are cocked by electric or hydraulic devices. See photos on http://www.giscogeo.com/pages/giscosei.html=20 =20 We would like to make a significant improvement in energy output. You = could make a better hammer and plate, but probably not twice as good. =20 I have considered flywheel operated devices. You could spin up a = flywheel with a battery operated drill and then couple the energy into the ground somehow, though there are strange forces going in strange directions = when you suddenly stop a spinning flywheel. =20 Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of ChrisAtUpw@....... Sent: Thursday, July 21, 2005 4:22 PM To: psn-l@.............. Subject: Re: Modified sound card and datalogging and geophones =20 In a message dated 22/07/2005, dcrice@............ writes: 7) And last but not least, it needs to work better than a sledgehammer = used with a seismograph that can stack multiple impacts. Hi Doug, =20 This may be a bit ''off the wall'', but there is another way of = looking at the problem.=20 =20 Can we design a better type of sledge hammer + plate / falling = weight?=20 =20 Regards, =20 Chris Chapman

A sledgehammer = is operated by swinging it through about a 250 degree arc, presumably by a muscular associate. If you were to replace it with a weight drop, = you would need to drop it many meters to approximate this amount of energy. = Thus, your weight needs to be accelerated somehow. There are units that = attach to vehicles with large rubber bands. They are cocked by electric = or hydraulic devices. See photos on http://www.giscogeo.= com/pages/giscosei.html

We would like to make a significant = improvement in energy output. You could make a better hammer and plate, but = probably not twice = as good.

I have considered flywheel = operated devices. You could spin up a flywheel with a battery operated drill and = then couple the energy into the ground somehow, though there are strange = forces going in strange directions when you suddenly stop a spinning = flywheel.

Doug Crice = ; http://www.geostuff.com

Wireless Seismic = http://www.wirelessSeismic.com

12996 Somerset Drive &n= bsp; phone 1-530-274-4445

Grass Valley, CA = 95945 USA fax 1-530-274-4446

-----Original = Message-----
From: = psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@.......
Sent: Thursday, July 21, = 2005 4:22 PM
To: = psn-l@..............
Subject: Re: Modified = sound card and datalogging and geophones

In a message dated 22/07/2005, dcrice@............ writes:

7) And last but not least, it needs to work better than a sledgehammer used
with a seismograph that can stack multiple impacts.

Hi = Doug,

&nbs= p; This may be a bit ''off the wall'', but there is another way of looking at = the problem.

&nbs= p; Can we design a better type of sledge hammer + plate / falling weight? =

&nbs= p; Regards,

&nbs= p; Chris Chapman

Subject: Re: Modified sound card and datalogging and geophones From: BOB BARNS royb1@........... Date: Thu, 21 Jul 2005 20:57:23 -0400 Doug, For a "ground-pinger": make a fitting to attach a bicycle pump to the screw cap on a large plastic (one liter?) soda-pop bottle. Bury the bottle down to the neck (or deeper) and pump until the bottle fails. (I don't know how much pressure these things will stand.) It might be better to weaken (say by scoring) the bottom so the push is vertical rather than horizontal (as when the side fails). Alternatively, the sides could be reinforced by wrapping with duct tape. This scheme meets your criteria except the "multiple impact" and possibly the "ping instead of thump" but it's hard to beat for cheap. A glass bottle might be more ping-like but would leave a hazardous residue. Bottles made of a brittle plastic (e.g., polystyrene or methyl-methacralate) might be better that the usual. It would be easy to try (but not by me). I considered pumping water instead of air but air would give greater impact because the stored enrgy is much greater. That's why pressure testing of high pressure gas tanks (e.g., oxygen) uses water rather than a gas. Another scheme:introduce a standard spark plug into a pop-bottle just below the neck. Run two wires (thru a rubber stopper in the neck or a screw cap) into the borrom of the bottle into an inch or so of water. Bury the bottle. Pass current (for a predetermined time)thru the water which fill the bottle with oxygen and hydrogen (the mixture will be stoichiometric). Fire a spark thru the plug. A stoichiometric mix of oxygen and hydrogen will detonate, not just burn. This should give a "ping". I suppose that a blanket should cover the ground above the bottle to catch the spark plug. Bob Barns Doug Crice wrote: > For as long as I have been in seismic, people have been trying to build a > good energy source for engineering seismic studies. Let me define such a > device for you experimenters out there. > > 1) A person ought to be able to carry it around > 2) It needs reasonably high frequency output (ping instead of thunk) > 3) Build it for $1000 or even $2000 in lots of 10 units, using new > commercially available and machined parts. > 4) It should be safe, even when used by students > 5) There should be no significant regulatory issues (a problem with > dynamite, the perfect source) > 6) Operating supplies available in third world countries. > 7) And last but not least, it needs to work better than a sledgehammer used > with a seismograph that can stack multiple impacts. > > The in-hole shotgun comes close, but it is possible to shoot yourself in the > foot, blow your hand off, and in one case, blow your brains out. The > associated liability prevents any real company from producing the device. > Even if you made it impossible to accidentally hurt yourself, under our tort > system, you would still be liable for intentional injuries. > > Geostuff will be happy to sell the device using our worldwide network of > contacts, assuming it works and is reliable. Mechanical things tend to self > destruct. > > Doug Crice http://www.geostuff.com > Wireless Seismic http://www.wirelessSeismic.com > 12996 Somerset Drive phone 1-530-274-4445 > Grass Valley, CA 95945 USA fax 1-530-274-4446 > > > > I know a gun fired in the ground is not a good source and that's > why I included a drop hammer lifted by a bank and dropped back > on the rod that is attached to a steel plate that sets on the > ground. I may have to use a propane to lift the slide over the > piston instead of a blank shot gun shell, > > > > > __________________________________________________________ > > 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. > > __________ NOD32 1.1175 (20050721) Information __________ > > This message was checked by NOD32 antivirus system. > http://www.eset.com > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 21:11:32 EDT In a message dated 21/07/2005, gcouger@.......... writes: The 5 volt one Hz signal off a Rockwell Jupiter or many other GPS receivers makes an ideal heart beat for a clock for an microcomputer. If you need finer granularity a divider or phased locked loop on the 100 kHz output is