PSN-L Email List Message

Subject: Re: Counts
From: "Geoffrey" gmvoeth@...........
Date: Wed, 29 Apr 2009 19:36:36 -0700

Im not sure what you guys are talking about
BUT I thought all you need to do is
to increase the gain until you see
about +/- 2 counts of background noise.
Then you shall see about anything that sticks
its head above the grass.

----- Original Message ----- 
From: "Robert McClure" 
Sent: Wednesday, April 29, 2009 10:02 AM
Subject: Re: Counts

> Hi Ted,
>  I use the 12-bit Dataq DI-154 for data acquisition. I aim for about
> 100 microns per second for full scale output. To find out what is the
> corresponding gain value to use to obtain this requires calibration of
> your sensors. Please see my web page
> for my calibration
> procedures.
>  Also, for short-period amateur vertical sensors, inverse filtering
> is very advantageous for obtaining longer period response. See my web
> pages for discussion of inverse filtering and download of  the
> WQFilter utility program for inverse filtering of WinQuake files.
> Bob
> On 4/29/09, tchannel  wrote:
>> Hi Folks,  I have two vertical sensors in test, both using Larry's one
>> channel board and DATAQ adc.   One of the boards is set for low gain and one
>> is set for high gain, using the jumper.
>> The first earthquake records was the 5.6m in Mexico April 27th.   Not
>> unexpected the counts on the one using high gain was 10x the one using low
>> gain.   Something like 70 vs 700.
>> Both traces looked fine and I could see little different, aside for the
>> counts.   My question is what should my count target be?   Someone may have
>> indicated about 100 to 300 counts during the quiet of night?
>> The reason I ask is I see data files posted with many using higher counts
>> 700 or 800, instead of smaller numbers.    I know the higher gain feature on
>> the board is for lower voltage output.   My coil and magnets are similar to
>> Chris's quad magnet arrangement, and a coil of 4000 turns, so I have plenty
>> of voltage.
>> I would like your opinions and why.
>> Thanks, Ted
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