On 7/18/02 8:35, Bill Tippett at btippett@alum.mit.edu wrote:
>K4OJ:
>In a low power environment nobody can argue successfully with me that CW
>isn't a better node!
Technically, you're incorrect. Human-read CW signals are limited by being
audible above the noise. Certain digital modes can greatly exceed that
capability.
N4HY and W3IWI did experiments back in the mid-80's where they did
MOONBOUNCE with weak 432 MHz signals. (They actually read the CW off the
FFT displays from their transceivers.) Once you bring signal processing
to the problem, new types of communications are possible -- ones that are
not limited by the human ear.
> This is also true on the low bands. Proof - compare alltime
>SOSB records for CW vs SSB on 160-40 in the CQ WW records here:
Bill, this is so fallacious an argument, it is almost ludicrious to
reply. Not only does one have to contend with the different bandwidth
requirements of SSB over CW, but the world-wide frequency allocations are
so varied that simplex communication, the mainstay of high-speed contest
operation, are not possible on SSB -- but are common for CW.
> In the extreme conditions on the low bands, CW rules!
Over SSB, sure. CW requires almost 100th of the bandwidth of SSB. It's
information rate is much lower.
Dr. Shannon has a well-known theory about information transmission.
Sending information and lower rates requires less bandwidth, and can
therefore be done at lower signal levels.
By that rule along, modes like PSK31, whose information rates are lower
than some CW signals, ought to be superior with weak signals.
--
PS -- does NASA use CW on its deep-space network?
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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