PSN-L Email List Message
From: rsparks rsparks@..........
Date: Thu, 30 Apr 2009 16:07:57 -0700
You raise an interesting question--What is the "grass"? =20
For some folks, it is the microseims apparently generated by ocean waves =
and maybe atmospherics. For others, it is local man made noise. For sti=
ll others, it may be the electronics of the amplifier, or noise from hing=
es or other seismometer parts.
If your hinges and electronics are reasonably quiet, you should be able t=
o see much smaller vibrations "riding" on the traces from the microseims.=
I like counts of 60 to 100 for the microseims so that I can see small l=
ocal quakes that are of higher frequency than the micoseims but much smal=
ler magnitude. Counts like this also pick up local noise but a quake loo=
ks a lot different from a car going by.
BTW, I am using the Saum system that uses a 16 bit A/D and has a peak co=
unt of +/- 32768.
Subject: Re: Counts
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 =B1 2 counts of background noise.
Then you shall see about anything that sticks
its head above the grass.
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