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Re: LF: Re: Transatlantic beacon tests

To: rs[email protected]
Subject: Re: LF: Re: Transatlantic beacon tests
From: "Rik Strobbe" <[email protected]>
Date: Thu, 27 Apr 2000 13:57:45
In-reply-to: <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
I think that Andy's (G4JNT) approach to go to milli-Hz bandwidth will be
very usefull in exploring the limits of what we can do with our small
antennas and 1 Watt ERP limit. It may also give us some interesting
information on propagation.
But due to the very narrow bandwidth the 'speed' will also be extremely low. Practise has learned us that a basic QRSS QSO at 3 sec. dot length takes
about 30 minutes. As 1mHz bandwidth corresponds to a dot length of 1000
seconds a minimal QSO (exchange of calls and 'TMO' report) will take about
16 hours. The question is if we will have a 16 hours long period of
ionospheric propagation over a 4000km long path ? Otherwise we will need to
rely on the surface wave and the disadvantge of this is that it has a
'coaxial cable like' attenuation of 2 to 3 dB per 100km. This means that
you need 40 to 60dB more power (or better SNR) to cover a 4000km path
compared to a 2000km path.

My opinion is that we should try all possibilities, going from normal-speed
CW over QRSS and DFCW to the milli-Herz techniques that Andy is developing,
in our attempt to cross the pond. Even within a small community as our 'LF world' there are different groups
of interest. But I see this as a benefit, not as a problem.

73, Rik  ON7YD



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