[email protected] wrote:
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!)
If you are limited to 1 watt dc input it would be interested to know what your
expectations are of crossing the Atlantic to the UK on qrss. I rate your chances
as NIL, except you have an exceptional antenna system. Please give me more
information and I will endevour to have a qso with you.
The best that I can manage is a 120 ft tower with a comprehensive top loading
system and and a good elevated radial system and 1 watt erp. One other station
to
contact is MM0ALM near Aberdeen in Scotland. He has two large towers each about
140 feet high and a good antenna system suspended between them plus an elaborate
radial system, and could possible get 1 watt erp out. One other that would be
closer to you is GI3OQR, he has two 150 feet towers separated by 500 yards and
although he is not active on 136 has the capability to listen for you. Give me
some details about your experiments.
I will also be in Tyrone (N.Ireland), which is closer to the USA in February for
2 weeks and will try to work the USA preferably on normal cw but I also have
qrss
facilities.
My antenna system there is also a 120 ft tower on a small farm similar to the
Scarborough qth system. I could possible extend the height conveniently to 140
feet, giving me a little more advantage.
Erp again about 1 watt.
Please let me have your observations.
de Mal/G3KEV
> 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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