In a message dated 99-12-21 11:44:43 EST, malcolmg3kev writes:
All messages appearing recently regarding QRSS are stating the
obvious as regards the technicalities. ie signal over noise in a very
narrow bandwidth. No one mentioned the big disadvantage of the time it
takes to have a qso.
This has been mentioned quite a bit from the very first use of QRSS,
actually. It was the principal reason for the recent development of DFCW.
I suppose if one has a poor antenna, low power and a noisy qth
then maybe qrss is the only way if you must work on 136 khz.
Or, if one is attempting longer distance than the available power and
antenna would normally be capable of reaching.
Sometimes the obvious statement _is_ the best answer. Signal-to-noise
versus bandwidth is more than a technicality, given the limitations that are
just plain unavoidable in amateur LF work. One way and another, "poor
antenna, low power and noisy QTH" describe life for nearly everyone who works
LF bands; and there's only so much that can be done to improve any of those,
especially in heavily populated areas.
(One watt ERP is a pretty significant limit by itself, apart from the
practical realities which make it unrealistic for most amateurs to achieve.
On this side of the pond, where the limit is presently one watt DC input
instead of ERP, anything that helps make contact is welcome!)
The same argument could be used for using qrss on all other radio
frequencies ie 160 and 80 metres but I am not aware that such techniques
are being used.
With power limits on the order of hundreds of watts, vastly more
efficient antennas, and significantly less QRN, there is much less need at
those frequencies.
However, given that QRP operation is a popular subset of amateur
activity, it's entirely possible that we may see it tried on HF as well.
Commercial operators on LF and VLF have adopted the MSK and PSK
approach.They need speed to move the traffic and cannot spend several
hours on one QSO.
Precisely why they erect huge masts, bury vast fortunes in copper, and
pump hundreds of kilowatts into the whole system. Were we able (and
permitted) to do the same, there would be no point in QRSS for us, either.
There is a possibility that qrss could be a lazy mans cw !!
I had some thoughts on that, but I think I'll go lie down now. :-)
Merry Christmas and Happy New Year, all!
73,
John KD4IDY
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