Hello Tamati;

Whats the frequency of the noise ?

If it is greater than 1.5Hz closer to 3Hz
it most probably relates to human activity.

If the noise is longer than one second
I might seriously consider expansion
and contraction or some other
form of non-man made noise.

I have this problem with my refrigerator
being on the same circuit as my electronics.

I have never been able to keep the
voltage spike that happens when the
refer cuts off from invading my electronics.

You might want to dummy load the input to your
electronics totally eliminating the sensor
to see if the noise is still there then
you can isolate the noise to electrical
or mechanical. While "dummied" You should have zero or only tiny
low freq. noise relating to temp changes of the
electronics and nothing more.

If the noise is asymmetrical you might consider
RFI as a concern and see if someone is operating
a transmitter close by. Police and fire and government
and public services (utility workers) will swamp my
amp when they are in the area and cause asymmetrical
noises. (lopsided waveforms more positive than negative)
A cell phone or CB radio does not seem to do this
I think the officials are transmitting with inputs in excess of 5Watt
of power.

Good luck,
Chris knows more than I do about this stuff.

regards;
geoff


----- Original Message ----- 
From: "chief.cook.nz" 
To: 
Sent: Thursday, November 23, 2006 3:01 PM
Subject: Re: Noise


Hi Ted
Which country are you in

Cheers Tamati
From the Castle of Tamati, Hinemoa and Karauwa the Dog
From the Castle of Tom, Robyn and the Dog

I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195
                              Bush Telegragh:- chief.cook.nz@............
                       My Regular Pitstop:- Tamati
                                                                  P.O.BOX 19-356 CENTRAL
                                                                  HAMILTON
                                                                  NEW ZEALAND
  ----- Original Message ----- 
  From: tchannel
  To: psn-l@..............
  Sent: Friday, November 24, 2006 7:08 AM
  Subject: Noise


  Hi Folks,  A while back I asked for help in determining the source of some noise showing up on my Helicorder.   This is an update 
to that question.
  I have excluded auto traffic, as the noise happens weather it is weekends or work days, at about the same time.
  I have excluded the schools in the area for the same reasons
  I have excluded construction for the same reason.

  I am not 100 percent sure of these exclusions, but for the most part, I think it is something else.

  I have gone back several days on the Helicorder to see if I could find patterns, and I have found that all is quiet starting about 
5:00 pm local time, 00 UTC.  Things remain quiet until 08:35 am, 15:35 UTC.   During the hours 8:00 am to 5:00 pm the noise comes 
and goes sometimes lasting less than one mins and sometimes lasting 5 to 10 mins.

  The sensor, a Lehman, is in my basement.  It is on a concrete floor next to a concrete wall, and the house above is wood and 
brick.
  Could this noise be the sun?  At about the time the noise begins the sun rises above the trees and shines on the east side of our 
house, which is also the wall near the sensor.
  Could this warming of the wood and bricks, above the basement, and their expansion cause the noise.  As the clouds block the sun 
during the day, might this cause the intermittent noise during the day?   The noise stops about the time the sun no longer hit the 
house.

  I could test this theory on a overcast day and I will do so, but I just wanted to get your input.

  Thanks, Ted 

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