RE: [wsjtgroup] Digest Number 755
- Could it be a BPL type system, I hear something very very similar on 2m and
its part of the VLF Electric meter reading system in Macon Co. The meters
use a VLF signal at 2-20 Hz but the microprocessors run on 144-148 MHz (not
cool) there is a chance that some utilitys equipment has a microprocessor on
the 50MHz band, I have notice that around here the meters have notch filters
for the Public saftey bands, the local utility was unaware that the 144-148
band was used by anyone, might be something similar there. Good luck finding
and curing the problem. I still find 2m weaksignal very dificult and
challenging. But it makes the contacts much more satisfiying knowing I did
it over all the noise and QRM.
Matthew Chambers, KC�QEV -- MAC201
ARRL Member -- ARES -- NWS Severe Weather Spotting Network
Macon Missouri EM39ss -- Listening on 146.805, 146.520, 146.580, 144.200
SWOT #3468 Member WSJT-Group
Exploring VHF Weak Signal
On Tue, 13 Sep 2005, wsjtgroup wrote:
Date: Tue, 13 Sep 2005 09:31:45 -0500 (CDT)
From: "Jonathan L. Rosner" <rosner@...>
Subject: Re: Spurious 6 m signal
This sounds rather similar to what we have been experiencing at the
University of Chicago for the past two years. I have not tried to find
the source, figuring it was a new piece of apparatus somewhere in the
University for which there would be no remedy.
Joe, maybe you could record a short .wav file of the sound this thing
makes and send it to us on the reflector. Just a guess: Is the signal
coming from the direction of the University? (Maybe the Engineering
As a result of this signal I have had to choose my 6 meter FSK441A
frequencies VERY carefully. There is still an S5 pulsing broadband noise
all up and down the band.
Jonathan L. Rosner Phone: 773-702-7694
Enrico Fermi Inst., U. Chicago Fax: 773-702-8038
5640 S. Ellis Avenue rosner@...
Chicago, IL 60637 USA or rosner@...
On Tue, 13 Sep 2005, Joe Taylor wrote:
This is perhaps a rather odd question to post on this reflector, but
there are lot of smart people here, and someone here just might know
what I'm talking about.
Several months ago an odd spurious signal turned up here on the 6 meter
band. I have been hoping it would go away, but maybe the time has come
to track it down. I can peak my antenna on it, so I know the direction
fairly well, but so far I have no idea how far away the source may be.
The signal has the following characteristics. There is a main "carrier"
at 50.161 MHz, and many sub-carriers at intervals of about 3.7 kHz up
and down the band from there. Up the band, the same thing occurs
centered on 50.236, with many sidebands up and down from there.
Between all of these sidebands or sub-carriers there is broadband noise,
and the noise is modulated on and off with a square wave. The period of
the square wave is about 0.83 seconds.
The signal is fairly strong, so the 6 meter band is pretty well messed
up around here. Does anyone have a notion as to what this intruder on
our band may be?
-- 73, Joe, K1JT