From: "James Moritz" <j.r.moritz@herts.ac.uk>
Organization: University of Hertfordshire
To: rsgb_lf_group@blacksheep.org
Date: Thu, 1 Nov 2001 11:27:32 +0000
Subject: LF: "Weak CW" on 136.000
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Dear LF group, 

I too can hear this - it has always been there since I started on LF, 
and does sound like very weak CW, but is never readable. I can 
hear it at any time the noise level is fairly low, and it is normally 
always visible on spectrogram displays.

I had a look at it last night using Spectrum Lab and Argo at their 
higher resolutions, and it is not actually CW at all - it consists of a 
dozen or so carriers irregularly distributed between about 135.998 
and 136.001kHz. Some of these are rock steady, others were 
drifting up or down by a fraction of a hertz over the two hours I 
observed them. The different frequencies beating together gives 
the "CW" effect

The spread in frequencies and the amount of drift would be 
consistent with an assortment of crystal oscillators on the same 
nominal frequency - perhaps it is a harmonic of some popular baud 
rate or similar?

Cheers, Jim Moritz
73 de M0BMU