Why does no one seem to use over-damping
to obtain a velocity response from their geophones?


-----Original Message----- 
From: Christopher Chapman
Sent: Tuesday, May 17, 2011 7:55 AM
To: psnlist@.............. ; shammon1@.............
Subject: Re: Photos of your station





From: Stephen Hammond 
To: psnlist 
Sent: Mon, 16 May 2011 16:16
Subject: RE: Photos of your station


Hi Larry, here is the PSN San Jose hardware link http://pw2.netcom.com/~shammon1/AptosStn.htm Steve  Hi Steve, It would be most 
helpful if you could give the period of your Lehman and also the period to which the vertical is extended from 3 seconds. It is 
usually possible to extend the period below resonance with a 1/f^2 filter by x10 without running into noise problems. You can also 
do this for geophones, turning 4.5 Hz geopones into 0.45 Hz ones!  Regards, Chris Chapman


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