PSN-L Email List Message
Subject: Re: Noise floor
From: "Geoffrey" gmvoeth@...........
Date: Wed, 25 Jul 2007 22:28:56 -0700
At about 0.2 Hz is what I understand to
be natural microseismic waves relating
to ocean waves striking the shores.
I have noticed a quietness at the fundamental
freq of the sensor. Like, my geophone is
about 1Hz and the noise seems quietest at 1Hz.
If the electronics is poorly built
by this I mean the components are not
proper, you can get peaks in your filters
profile that will show up as increased
noise at that freq.
If your electronics is good enough you can
dummy load the input and get a flat line
on the output of your electronics.
I have never been able to acieve this
level of quiet.
Noise is interesting because youd think
if it were truly random it would be self
The narrower the bandwidth the less the noise.
The colder the less the noise.
If there exists a specialty science of studing
Id like someone to tell me what it is.
The best way to see earthquakes is to simply
limit the bandwidth then
amplify your sensors signals till you
see the noise. These EQ waves seem to ride
just above the "grass".
----- Original Message -----
From: "Paul Cianciolo"
Sent: Wednesday, July 25, 2007 10:33
Subject: Noise floor
> Hello Folks,
> I have uploaded to The PSN events page a file called vertical noise floor.
> This is the Noise floor of my new vertical sensor that has a period of 4
> Can someone please download the file with Winquake and do an FFT on the
> What you will see is a signature waveform that seems to be part of the
> machine I built.
> There always seems to be a lot of energy at .2 HZ with a roll of toward 1 HZ
> Does this being a log scale, mean I has some noise peak, at .2 Hz ???
> Is this real? or an artifact?
> Ted TCID sent me a raw file from his machine, and the response is much
> My next test is to lock down the coil/magnet sensor and take a reading and
> see what the noise floor looks like.
> When I replace the coil with a short circuit across the input of the seismic
> amplifier, I get what looks like a flat response line.
> Any ideas comments welcome.
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