Envelope-to: dave@picks.force9.co.uk
Delivery-date: Tue, 17 Jan 2006 10:39:04 +0000
Message-ID: <000a01c61b52$10796fe0$67b0fea9@lark>
From: "Alan Melia" <alan.melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <000701c61a8f$6ccf2c80$6401a8c0@JAYTERMINAL><20060116234132.jss0e6ldnj0g0880@webmail.versatel.de><001301c61af4$9db27ae0$67b0fea9@lark> <20060117110042.4fiu7hkxcquscoos@webmail.versatel.de>
Date: Tue, 17 Jan 2006 10:37:29 -0000
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Subject: Re: LF: Re: Propagation
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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

----- Original Message -----
From: <uwe-jannsen@versanet.de>
To: <rsgb_lf_group@blacksheep.org>
Sent: 17 January 2006 10:00
Subject: Re: LF: Re: Propagation

last EU nights my signs could be seen on the CT1BRT grabber in IN51QD ie
2120km/235dgr and at same times my signs where not visible on the screen of
W1VD in FN31MS ie 5943 km/293dgr.
and vv no signs on the CT1DRP grabber means the signs are visible on the
W1VD
screen.

do you have an explanation?


> Zitat von Alan Melia <alan.melia@btinternet.com>:
>
> > Hi Uwe was this one meant for me ??
> > Cheers de Alan G3NYK
> >
> >
> yes, Alan, sri for mixing up the callsigns.
>
> vy 73, Uwe
>
>
>