Dear Andy, LF Group,
Should be better now - I have been playing with antennas due to the problem
that arose yesterday with the increased noise levels. Incidentally, I just
saw your frequency jump from 503870 to 503885 Hz in the middle of the 1830
transmission, but still gave 0dB and +3dB SNRs - on two frequencies!
After going out and about with a loop and portable RX, I am now pretty
certain that the QRM is being radiated from the Brookmans Park transmitter
site. I am not entirely certain, but there seems to be some correlation
between the noise and the BBC R5 909kHz transmission audio, the antenna of
which is about 500m from here. This was also the case before, but the QRM
level has risen by about 20dB in the last day or so.
As an experiment, I have lashed up an EWE-like antenna, and with suitable
tweaking this gives about 20dB of unidirectional null, which has brought me
back to more or less where I was before, at least for signals coming from a
westerly direction. It is too big to be a permanent fixture, and also
interacts with the TX antenna. But I think similar or better results will be
achievable by phasing a vertical antenna against the existing loops here.
Cheers, Jim Moritz
73 de M0BMU
----- Original Message -----
From: "Andy Talbot" <[email protected]>
To: <[email protected]>
Sent: Sunday, February 01, 2009 5:26 PM
Subject: LF: 'JNT WSPR
Why are you reporting such a low SNR, Jim ?
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