ORIGINAL MESSAGE:
On Sat, 31 Oct 2009 21:19:01 -0700, Kok Chen <chen@mac.com> wrote:
>
>Bill, if you have done SNR studies that show that you do not need
>better SNR on the lower bands to print an RTTY signal when compared
>with the higher bands, or that the Watterson propagation model (used
>by the ITU 4187 and CCIR 520 standards) does not apply to lower bands,
>I am sure all of us would love to see it.
REPLY:
Chen, with all due respect, I think you spend too much time modeling propagation
and not enough time on the air actually doing it.
I have no idea what the "Watterson propagation model" is. I have no idea if you
"need a better SNR on the lower bands". I do know that RTTY works perfectly well
on 160 meters as proven by hours of actual on-the-air experience. Granted, 160
will never equal some of the higher bands in efficiency of communication. Nobody
ever said it would. But the same applies to VHF, UHF and microwaves. Are those
bands "useless" for ham operations? Of course not.
160 meters is different from the higher frequencies and that is part of its
charm, at least to me. Unlike the higher bands, 160 has essentially no "skip"
zone. Day or night, signals will be reflected. The only question is the amount
of absorption. To an extent, power will overcome absorption and that is why high
power amps are very desirable on 160. Compare this with 10 meters. When 10 is
open you only need a few watts to work the world. When it is not open, a
kilowatt will not help. Very different from 160. Groundwave coverage on 160 is
superb, much better than any other ham band. My friend Jim, AD6WL is about 80
miles from me. We can easily communicate with 100 watts of RTTY on 160, where on
10 meters with kilowatt and beam, communication is impossible. We have tried.
Hams have a tradition of experimenting and love to prove the experts wrong. It
would take pages to list the things that "couldn't be done" but hams went ahead
and did them anyway. The VHF path between California and Hawaii was long
considered impossible, but W6NLZ and KH6UK didn't believe it. The same year I
got my first license in the late 1950's they did it and I have been inspired
ever since.
See you on 1808!
73, Bill W6WRT
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