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From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
Date: Sat, 16 Sep 2006 00:47:37 +0100
MIME-Version: 1.0
Subject: LF: Simple path-loss calculation
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Status: O

After kicking this idea around for over a year privately with various
members of the group, I have decided to hoist it up the flag-pole to be shot
at !

I have read many attempts at calculating the LF field strengths expected
from a distant LF transmitter, and they all seem to have been over
complicated or give wildly inaccurate answers compared with our (amateur)
measurements. This included John Adcock's article which I think derives
figures from the CCIR recommendations. I am not greatly interested in paths
of less that 1500km, this is intended to assess DX paths.

After a lot of staring at my daily data plots, gallantly collected by Brian
CT1DRP, I derived a simple proceedure which will give a rough estimate of
the expected signal level. The calculation is ludicrous, in fact I called it
"Silly.htm" originally, and it was a bit of a joke.  It does however give a
useful figure which is, by my reckoning, not that far out. You must consider
that signal levels can vary by up to + / -6dB in daytime and around + / -
12dB at night due to fading and geomagnetic activity, so there is not too
much point in trying to be more accurate than that.

Shoot holes in it ......tell me where its wrong, but give the data to back
up your assertions. If it doesnt sink, riddled with holes, we might be able
to refine it to give better agreement with results. Do bear in mind it is
based on three years observations ! Thanks again Brian ! Find the
explanation at

http://www.btinternet.com/~alan.melia/simple.htm

Cheers de Alan G3NYK