Message-ID: <000e01c1a85d$74ff5540$682d073e@default>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: "LF-Group" <rsgb_lf_group@blacksheep.org>
Subject: LF: I.C.M or Luxembourg effect and Propagation
Date: Mon, 28 Jan 2002 23:44:43 -0000
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Hi all, I have had some more recent discussions with Vaino, OH2LX, on the
effect and have several maps of his observations, which centre mainly around
a high power Polish LF station. Victim stations seem to be located with a
bearing passing as far as 50kM from the offending station. Since BC stations
radiate from vertical masts, I naively thought there would be no effect from
a bearing straight throught the  'causing' station. This is not true, I
guess due to the disturbance at an elevation of 60 degrees or so in front
and behind.

I often hear the 'signature tune' with the two 'gong' tones that Peter G3PLX
mentioned. One more recent subjective observation (as a result of my
propagation observations) is that the Ionospheric Cross Modulation (ICM) is
always noticable (worse??) when there has been a geomagnetic storm (usually
peak radio effects are 3 to 4 days after the storm), and significant
disruption to LF propagation. I suppose this is reasonable as these events
inject high levels of ions (electrons) into the D-Layer. So there is more
material to 'work' with.  There has not been a major storm for some time but
for some reason there is a large reservoir of absorbing ions in the D-layer
which does not seem to be decaying very rapidly. One good point is that
these have led to good daytime conditions on 136 recently, though night-time
conditions have not yielded their normal high signal levels.

Cheers de Alan G3NYK
alan.melia@btinternet.com


Unfortunately Vaino is not fit enough to join in with the discussion, but I
am sure he is following it with interest.