Envelope-to: dave@picks.force9.co.uk
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Date: Tue, 17 Jan 2006 16:58:22 +0100
From: uwe-jannsen@versanet.de
To: rsgb_lf_group@blacksheep.org, Alan Melia <alan.melia@btinternet.com>
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Zitat von Alan Melia <alan.melia@btinternet.com>:

> Hi Uwe, yes it is a bit confusing as at first sight one would expect the
> signals to be present or absent on both grabbers.
>
> At night I think the main mode is a hop length of about 2000 km. See
> http://www.btinternet.com/~alan.melia/geometry.htm
>
> This is about the distance from Brian to DCF39. The night-time signals Brian
> recorded over several years were fairly consistent but did sometimes show
> severe dips in strength which I think are due to destructive interference
> (optical term) between the main mode and other paths (maybe a 2-hop path).
>
> The path to the States is roughly 6000kms which is 3 hops, but under
> conditions of low absorption it may be that a two hop signal (or a 4 hop
> signal) arrives, sometimes at a very similar strength. The result of this
> can be deep fades, but the timing does depend on the path length. It is
> interesting to watch Joe, Warren, John and Dex's signals. In particular
> although John and Warren are only about 80km apart there is a distinct
> difference in the times they fade and return....it can be as much as 15 to
> 20 minutes.
>
> The positive side to this effect is that if the phase difference is right
> you get a 6dB enhancement a short time later in the night. These are the
> "lifts" that lead to some of the first TA successes on 3 sec dot  QRSS (all
> that was available at the time using Robert Horne's Spectrogram)
>
> Interesting stuff this LF propagation !!
>
> Cheers de Alan G3NYK
>
OK. Alan, thanks. Im eager to see whether Bill/VE2IQ received any signs 
or not.
Regards
Uwe/dj8wx