Dear LF Group,
we should clearly differenciate between all aspects.
A propagation study does not need any information transfer
via the radio path other than confidence on the identity of
the station in focus. In that case, observing the carrier
is best. So WSPR has no advantage over QRSS.
On the other hand, WSPR has the advantage of automatic
recording. But that is not an advantage of the mode, it
simply is the lack of a corresponding simple program that
does the same with a QRSS signal.
If the propagation is monitored with the final goal to
make a QSO at appropriate conditions, then the information
transfer gets important. In that case, WSPR may outperform
QRSS by a few dBs (at the same error rate).
Nevertheless, WSPR is not very near to the Shannon limit.
I spent nearly all my leisure time of the last year with
the design of a new digital ham radio QSO-mode HD43 that
comes as close as possible to the theoretical limit.
I will send a preprint on request.
73 de Klaus, DJ5HG
> mal hamilton wrote:
> > On LF I do not think wspr is the correct mode to study propagation
>
> Good points Mal. However CW for manual reception and QRSS, to be viewed
> on a waterfall display, are fine for all manner of uses and in extremis
> QRSS is probably more sensitive than WSPR. However QRSS requires the
> receiving station to be actively watching the screen all the time, or to
> save traces automatically and then manually review them, by eye, later.
>
> This is rather time consuming and laborious.
>
> WSPR may have it's downsides, and the problems last night with G0NBD
> aside, I've never had any problems decoding anything I can visually see,
> and also much that I could not hear and would be at the threshold of
> QRSS useabilty.
>
> I have confidence that what I see reported by the software is a
> reasonable representation of what was transmitted, and it's much easier
> to quantify changes in signal strength vs time with the WSPR data than
> estimating by eye the quality of a QRSS transmission.
>
> It may not be accurate in terms of actual reported S/N ratio, but it's
> consistent from session to session, and gives numbers to work with, if
> that's your interest.
>
> Not everyone can sit waiting for the brief propagation opening, so
> automating the process at least adds another facet this interesting hobby.
>
> If it hurts no-one then what's the harm?
>
> Regards,
>
> John
> GM4SLV
>
>
>
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