RE: Raspberry Pi 2 Road Test Application Accepted - the Way Forward

DAB — Tue, 11 Aug 2015 19:40:57 GMT

HI Austin,

I too have a great interest in Geophysics, so I will be watching your progress and probably ask some strange questions, but I have a lot of out of the box issues I would like to explore about geology.

DAB

RE: Raspberry Pi 2 Road Test Application Accepted - the Way Forward

chuck_young — Tue, 11 Aug 2015 14:15:49 GMT

HI Austin:

I hope you will be able to spend some time with an engineering seismograph (e.g. something from Geometrics),

'cause then you will have a much better idea of where you are headed. I think that trying to image a buried pipe or tunnel

is difficult, even with commercial seismic equipment. You may be better off pursuing simple layered earth refraction or reflection results.

I have been interested in seismic reflection work using a hammer ever since I first heard of it.

You might be interested in the work of Pullan and Hunter, such as

ftp://geom.geometrics.com/pub/seismic/Literature/S-TR94.pdf

"Optimum window" is essentially a single channel approach. They were using an 8 bit ADC and an Apple II computer to do this in 1984!!!

This fellow devised a basic refraction seismic system using an ADC for his notebook computer. You might do well to start with his design.

Journal of Water Resource and Protection, 2011, 3, 768-780
doi:10.4236/jwarp.2011.310087 Published Online October 2011 (http://www.SciRP.org/journal/jwarp)

Inexpensive Geophysical Instruments Supporting Groundwater Exploration in Developing Nations

James A. Clark1, Richard Page2

1Department of Geology and Environmental Science, Wheaton College, Wheaton, Illinois, USA 2Design Engineer, Wheaton, Illinois, USA
E-mail: james.clark@wheaton.edu

Are you planning to use the Element14 Cirrus or Wolfson audio card? The good news is that they have good dynamic range and

high sampling rate, but the bad news is that they are only two channels. My thought is that you should also look at the

AdaFruit ADS1015, (12 bits, 4 channels, 3300 samples per sec rate).

Another good way to go might be to use Audacity (freeware!) and a USB audio adapter

(16 bit stereo, cost around $5). I tested this for another application. I think this would work well for Clark and Page's project (above).

A regular geophone is going to cost you about $50 each.

I have been experimenting with low cost geophone replacement, some kind of piezo element.

I can give you more details if you are interested.

I have had some luck displaying waveform cross sections with matlab (or octave). Actually, I was using radar data, but it's the same idea as seismic. In modern times, it looks like Python would work just as well.

If you get Seismic Unix running , I would like to hear more about it, especially if you get it running on the RPi.

I used SU on a Sun computer, and then on a notebook running Linux. It doesn't take all that much memory, but my thought is that

SU is WAY OVERKILL, for hammer seismic.

My current personal choice for small scale hammer seismic is a pocket sized digital recorder.

I have a Tascam DR-05 that I purchased for about $60 on EBay. I think would do just fine.

I hope you will post information on your progress here.

Chuck

(Yes. I am a retired professor of geophysics.)