Message-ID: <2000041223543468199@zetnet.co.uk>
Date: Wed, 12 Apr 2000 23:54:34 +0100
To: rsgb_lf_group@blacksheep.org
From: "Peter Dodd" <g3ldo@zetnet.co.uk>
Subject: LF: Re:  TransAtlantic II
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> From Dave G3YMC

> I wish Larry and the VE team all the best for their forthcoming
> transatlantic tests - the choice of a period in November is excellent, and
> if there is a chance then (and December) is the optimum time.

> I think it would have given Peter Bobek a very special thrill if his aims
> were met by a normal amateur using normal CW and an average station. 

I don't recall that DJ8WL had any hang-ups about using QRSS - in fact 
all my QSOs with him used this mode

Of the modes proposed for these Transatlantic tests the extremes are 
30 or 40WPM CW and slow CW that would take several hours.  From 
experiance gained in the last couple of weeks in crossband tests on 
72kHz/137kHz, mainly with I5TGC, I feel that the following notes may 
be of some interest.

Even in good conditions a signal radiated from 1W erp is going to be 
very weak by the time it has travelled 3000km, even on a sea path. In 
periods of exceptional conditions such a signal may be audible but a 
much greater chance of success can be had by using QRSS. This can 
illustrated by a 72/137kHz cross-band I had with OH9UFO. Reino was 
using nomal CW on 137kHz. I was a comfortable 'O' on QRSS. I was 
asked to try fast CW and Reino copied his report and gave me 329 - 
then lost it. This QSO was very marginal and if it wasn't for the 
inital QRSS contact it would not have happened.

We have very little knowledge of the long distance propagation 
mechanism of weak signals at LF. All we can say is (from observing 
commercial stations) that they seem better in Winter at around 
0400UTC for this path. The greater the distance the shorter the 
openings so digging the signal out of the noise using very long 
integration times is impractical.
The openings for the I5TGC experiments lasted half an hour, which 
gave plenty of time for QRSS with a dot length of 3 or 4 seconds.

Exceptional conditions can occur any time so we should not confine 
the tests to special expeditions. We should have a plan.


-- 
Regards, Peter, G3LDO

<g3ldo@zetnet.co.uk>