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Subject: Re: Got it going I think
From: BOB BARNS royb1@...........
Date: Sat, 02 Apr 2005 20:46:56 -0500

   My suggestion for setting the gain is to set it for just a few counts 
from the A/D on a very quiet day.
Bob Barns

ChrisAtUpw@....... wrote:

> In a message dated 02/04/2005, 1goss@........... writes:
>> I got my Lehman Seismometer up and running I think I may have my gain 
>> set a bit high, But I think it is ok.
> HI Bryan,
>        It looks like you have a fairly high gain on the amplifier. I 
> suggest that you examine sections of the trace, do a FFT on it and check 
> to see if the ~six second ocean background is dominant or if there is a 
> lot of other noise. Try wedging the mass so that it can't move to check 
> on instrument noise? I can't tell much from the drumplot, since I don't 
> know how it was scaled. It doesn't show any waveforms or any peak 
> counts. You need to click on X-Scale at the top of the display and then 
> select 'counts'.
>        The display shows small deflections during the night, but much 
> larger ones during the 'working day'. Do you have a lot of traffic / 
> industrial noise?
>        What sort of suspensions / bearings are you using? A 12 sec plot 
> doesn't give you much 'headroom' over the 6 sec microseisms.
>        Regards,
>        Chris Chapman


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