PSN-L Email List Message
Subject: Re: L15B 4.5 Geophone, detecting teleseismic earthquake
From: Stephen & Kathy skmort@..........
Date: Fri, 31 Mar 2006 10:15:32 -0800
Count me in,,, I'd like to see your circuit!!!!
PSN Station #55
> In a message dated 31/03/2006, system98765@............. writes:
> Hi Chris (& everyone else),
> Where can one get more information about the 'Roberts Amplifier'?
> Hi Kareem,
> Go to http://psn.quake.net/bibliography.html
> Roberts, PM "A Versatile Equilization Circuit for Increasing
> Seismometer Velocity Response Below the Natural Frequency." (for 4.5Hz
> geophones) BSSA, vol 79, pp 1607-1617 Oct. 1989
> Your local library should be able to get you a photocopy.
> I made some simple circuit changes which reduced the very low
> frequency noise, if anyone is interested. The modified circuit seems to
> work fine. Lennartz use geophone compensators of this general type on
> their professional range. You get about a factor of 10 reduction in the
> minimum frequency - e.g. a 4.5Hz geophone will reproduce ~flat down to
> 0.45Hz. This enables you to pick up teleseismic quakes as well as local
> and regional ones.
> Chris Chapman
Public Seismic Network Mailing List (PSN-L)
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