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[RFI] 80M mystery noise

To: rfi@contesting.com
Subject: [RFI] 80M mystery noise
From: Pete Smith <n4zr@contesting.com>
Date: Tue, 13 Nov 2007 16:39:54 -0500
List-post: <mailto:rfi@contesting.com>
This thing (or rather, thingS) has appeared in the last few months.  It 
occurs at intervals across the CW band, at widely different signal 
strengths, regardless of time of day (high noon, for example), so it must 
be near field or groundwave.  The intervals appear to be roughly every 1.8 
KHz, but the signal strengths vary so much that I'm tempted to speculate 
that it may be a number of identical devices at different distances from 
me, and with slightly different frequency-determining components.  Or, 
conceivably, they are all harmonics of a 1.8 KHz source.  I can't DF it at 
all precisely, due to a lack of sufficiently directive RX antennas (a K9AY 
loop just doesn't cut it hi), but most of them appear to be north of me.

The enclosed recording was done in CW position, on my Mark 5 with 2.8 KHz 
filtering.  Looking at it on Spectran there are two distinct, fairly narrow 
alternating carriers, each of which shifts frequency slightly during its 
"on" period.  I caught one of them with the screen capture, but you can see 
from the waterfall that the other, which is slightly lower in frequency, is 
similar.  Nothing is audible in AM mode.

If you think you might be able to help ID this thing, please go to 
www.pvrc.org/n4zr/80m_mystery_noise.htm to listen to it and look at the 
Spectran signature.  Thanks!

73, Pete N4ZR
The World HF Contest Station Database
Full details on 3300 contest stations
Updated 5/5/07 http://www.pvrc.org/WCSD/WCSDsearch.htm

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