On 8/5/02 11:50, Bill Tippett at btippett@alum.mit.edu wrote:
> Under extreme contest conditions on any band, CW rules!
Does it? That's an open question.
>Why
>is this so? The answer is very simple...noise bandwidth. On the
>low bands, noise tends to increase as you move down in frequency.
[ Sound reasons removed ]
>Because of noise, any mode which allows a smaller (i.e. narrower)
>noise bandwidth will be more effective in communications than a mode
>which requires larger bandwidths.
This is essentially Shannon's law. (Actually, the law takes into account
both the bandwidth and the threshold above noise -- the total area
therein defines the maximum information content that can be moved aross a
defined channel)
So, it follows that ANY mode (as you indicated) which has a narrow
bandwidth would be effective on these noisier bands.
One DISadvantage of CW is that the transmitter isn't always keyed. At
extremely low signal levels, it is hard to discern at the receiver when
the signal is present and when it is absent. For this reason, FSK and PSK
have a distinct advantage over OOK (CW) -- at least a 2 dB advantage.
> I don't believe any current digital mode has an advantage
>over either CW or SSB in contest conditions, not due to any
>bandwidth considerations, but simply due to the awkwardness of the
>human/computer/radio interface in making contacts rapidly (tuning,
>identifying, exchanging, etc.) IMHO the human brain coupled to a
>radio is a far more powerful combination under contest conditions
>than any mode which requires a computer for coding/decoding signals.
>This might change in the future but that's how I see it today.
I've never seen it in actual use, but there is an application called
RITTY, that apparently makes RTTY contesting very fast an effective.
There's also a RTTY contest application that works in concert with it.
I believe the future may have already arrived when you weren't
watching....
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
|