Dear Steve, LF Group,
At 09:42 06/10/2002 +0100, you wrote:
Yesterday evening and this morning I'm getting a keyed beacon at about
136kHz, just below the level wher my ears or the computer can decode it. Can
someone tell me what it is, or is it a phantom?
Thanks,
Steve
As Mike says, this is something many of us can hear - looked at on a high
resolution spectrogram it consists of a number of weak carriers on almost
exactly 136.0kHz - these beat together to produce the "CW beacon" effect.
My favorite explanation is that these are harmonics of telecomms clock
signals on 8kHz, being radiated by phone wires, etc - there are different
signal components present in different locations. So this could well be a
form of fairly local QRM rather than a receiver problem or an intermod. I
also hear something similar on 72kHz when Rugby is QRT.
Cheers, Jim Moritz
73 de M0BMU
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