PSN-L Email List Message
Subject: Re: Metods for Improving SNR for events ??
From: "Connie and Jim Lehman" lehmancj@...........
Date: Sun, 17 Sep 2006 19:41:13 -0400
Jerry--improving SNR is always an ongoing effort in amateur as well as =
professional seismology. In my day of recording we worked with passive =
filters to take out 60 hz and mechanical noise from climate control =
chillers, etc. As long as microseisms were evident, we knew the system =
was working. Here in Virginia we are entertained by variations in =
microseisms from day to day, sometimes hour to hour--hurricanes hitting =
Florida and moving up the coast. Winter storms coming from Tennessee =
eastward to the coast, highs & lows in barometic readings, etc. For =
some unexplained reason, microseismic amplitudes were generally low in =
May to August--we could almost double the gain of amplification--
You speak of your systems on a concrete floor of a garage. I do not =
know your location, but here in VA we ran a long period system under =
those conditions where temperatures varied as much as 30 degrees F. from =
day to night. Not only do componets of the sensor respond, but concrete =
has an amazing way of microscopic shrinking and expanding, and these =
appeared as periodic peaks or snaps on the record. Winds are frequently =
with us, and if trees are within several hundred feet of your sensor, =
the crowns are stressed by wind and this stress is transferred to the =
root systems and propagated to the sensor.
I know there are active filters out there now that work wonders in =
minimizing noise--but I still find myself looking at the microseisms =
before and after an event to give me a frame of reference on the event.
A good day to all Jim Lehman
----- Original Message -----=20
From: Jerry Payton=20
To: PSN-L=20
Sent: Sunday, September 17, 2006 11:00 AM
Subject: Metods for Improving SNR for events ??
Is there a way or ways to improve the SNR (signal to noise ratio) of =
an incoming event? =20
I realize that if the incoming rays are not strong enough, they will =
not overcome the ambient noise of the system.
I would further assume that lowering the ambient noise is the best =
solution, but I understand that can be a real challenge. Personally, I =
live in a wooded area, remote from vehicle travel and most man-made =
noises. But, weather and wind will affect my noise =
significantly......something I have to live with.
My vertical and horizontal sensors are simply laying on a concrete =
floor in an unattached garage with proper covers over each. Any gain =
adjustments raise or lower the noise factor directly. I guess that =
finding a "happy level" and living with it is my only solution. But, if =
there are any suggestions or remedies out there, I'd appreciate knowing =
about it..
Best Regards,
Jerry Payton=20
Jerry--improving SNR is always =
an ongoing=20
effort in amateur as well as professional seismology. In my day of =
recording we worked with passive filters to take out 60 hz and =
mechanical=20
noise from climate control chillers, etc. As long as microseisms =
were=20
evident, we knew the system was working. Here in Virginia we are=20
entertained by variations in microseisms from day to day, sometimes hour =
to=20
hour--hurricanes hitting Florida and moving up the coast. Winter =
storms=20
coming from Tennessee eastward to the coast, highs & lows in =
barometic=20
readings, etc. For some unexplained reason, microseismic =
amplitudes were=20
generally low in May to August--we could almost double the gain of=20
amplification--
You speak of your =
systems on a=20
concrete floor of a garage. I do not know your location, but here =
in VA we=20
ran a long period system under those conditions where temperatures =
varied as=20
much as 30 degrees F. from day to night. Not only do componets of =
the=20
sensor respond, but concrete has an amazing way of microscopic shrinking =
and=20
expanding, and these appeared as periodic peaks or snaps on the =
record. =20
Winds are frequently with us, and if trees are within several =
hundred feet=20
of your sensor, the crowns are stressed by wind and this stress is =
transferred=20
to the root systems and propagated to the sensor.
I know there are =
active=20
filters out there now that work wonders in minimizing noise--but I still =
find=20
myself looking at the microseisms before and after an event to give me a =
frame=20
of reference on the event.
A good day to=20
all &nbs=
p; =20
Jim Lehman
----- Original Message -----
Sent: Sunday, September 17, =
2006 11:00=20
AM
Subject: Metods for Improving =
SNR for=20
events ??
Is there a way or ways to improve the SNR (signal to noise ratio) =
of an=20
incoming event?
I realize that if the incoming rays are not strong enough, they =
will not=20
overcome the ambient noise of the system.
I would further assume that lowering the ambient noise is the =
best=20
solution, but I understand that can be a real challenge. =
Personally, I=20
live in a wooded area, remote from vehicle travel and most man-made=20
noises. But, weather and wind will affect my noise=20
significantly......something I have to live with.
My vertical and horizontal sensors are simply laying on a =
concrete floor=20
in an unattached garage with proper covers over each. Any gain=20
adjustments raise or lower the noise factor directly. I guess =
that=20
finding a "happy level" and living with it is my only solution. =
But, if=20
there are any suggestions or remedies out there, I'd appreciate =
knowing about=20
it..
Best Regards,
Jerry Payton
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