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From: eric@batcomputer.tn.cornell.edu (Eric Fielding)
Newsgroups: comp.dsp
Subject: Re: Looking for Digitized Seismic Signals
Message-ID: <9795@batcomputer.tn.cornell.edu>
Date: 25 Feb 90 02:24:42 GMT
Reply-To: fielding@geology.tn.cornell.edu
Distribution: na
Organization: Department of Geological Sciences, Cornell University
Lines: 22

In a recent article lindi@watnow.waterloo.edu (Lindi Wahl and Tracey Bernath) wrote:
>I am presently working on an algorithm which locates disturbances in 
>constant frequency noise, and would REALLY appreciate it if anyone
>knows of some place I can get digitized seismic signals.  The best
>type would be low sig/noise, with constant freq background noise.

Well, I am not active in seismology now, but I can tell you that there
are many types of digital seismic data.  There are even some out on CD-ROM now.
The main differentiation is between earthquake data and seismic reflection
data where there is a human-instigated source that sends signals down into the
earth and records reflections from various layers.  I am not clear on what you
mean by 'const. freq. noise'.  There are quite effective, simple techniques
used primarily by earthquake seismologists to detect the 'first arrival' of
energy from an earthquake; the main unsolved problem is to distinguish the
various secondary arrivals from the coda of the first arrival.  The problem
is that the so-called 'source-generated' noise following the first arrival 
is not of constant frequency.  I don't know if even the background noise
before the first arrival can be considered constant frequency.

There are people here in my department that work on both earthquake and
reflection seismic data.
				++Eric Fielding