PSN-L Email List Message

Subject: WinQuake Times
From: RSparks rsparks@..........
Date: Tue, 10 Nov 2009 06:56:51 -0800

Good Morning Geoff,

I don't quite know how to react to your posting because I am not working 
much in the area of quake timing.  However, from the posting, I can see 
that you are watching my PSN quake reports so I need to tell you more 
about my equipment.

First, my timing is not very exact.  I installed a ClockCard into my 
computer, which is controlled by the software ClockWatch.  I think I am 
accurate to within one second but I recognize that is very poor accuracy 
for seismic work.

I am using a tweaked copy of Amaseis to record the events.  Amaseis uses 
the PC time to change hours and each event is expected to be regularly 
spaced after that.  Since my sample rate is about 10.3 samples per 
second, the chance of which hour the last/first sample fell into becomes 
a probability exercise.  I have never investigated the accuracy of the 
clock in the A/D device but it is pretty good so the samples should be 
well spaced.

I am using an earlier Saum A/D device that I modified slightly to have a 
wider frequency response, with the modifications hopefully increasing 
the high pass characteristics.  I was satisfied when I could see our 
local Washington quakes which have a higher frequency than the 
teleseismic events.

The sensor is the next step from the device I posted some time ago at 
Damping is with magnetic braking.  The device does not record a strictly 
vertical motion because the mass axis is tilted (to improve the low 
frequency response) giving a response similar to the response from the 
CSpring Seismometer (which is incorrectly claimed to be a (only) 
vertical sensing device).  Both the CSpring device and my present device 
respond to horizontal motion to the extent dictated by the vector angle 
from the pivot point to the center of mass.

Your comment about wave form seems to say that the wave forms between 
your recordings and mine seem to be similar.  If that is what you intend 
to say, I am somewhat surprised because this station is located between 
some mountains which I would (I think) cause reflections that would 
change the wave form.  I have wondered if amateur seismic stations could 
utilize the interference rendering technique to actually map the surface 
and subsurface features of the earth somewhat akin to what is done with 
medical imaging?  My own knowledge of imaging is too weak to venture an 

Thanks for sharing your results. 


psn-l-digest-request@.............. wrote:
> .------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
> | Message 1                                                           |
> '------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
> Subject: WinQuake Times
> From:    "Geoffrey" 
> Date:    Mon, 9 Nov 2009 13:37:09 -0700
> Hello PSN;
> I made the changes to a conversion program
> of my own to invent a PSN4 file for my data
> and wish to announce that since I have
> placed the fractional value of the start time
> times a billion into the NANO SECOND
> area the times I now get from winquake appear
> to be proper. I have tested this using
> pulse marks made by myself then gone back
> into the program and checked the times.
> The proper way would be to use WWV minute marks
> I have not yet done this however I expect for
> amateur purposes that would be correct also.
> I now feel I can resume sending reports
> to whoever and expect the times to be correct
> or as correct as can be for my station.
> GVA teleseismic events appear very close agreement
> in form to the fellow in Washington State so I am
> guessing that phase (up is up) is proper also.
> I only do an SPZ channel so can not compare
> with those using N or E sensors.
> Roger Sparks Device seems to have a lower freq
> response so our comparisons will rarely
> be exact yet they seem very close in appearance.
> geoff
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