On Jan 3, 2011, at 11:52 AM, Bill, W6WRT wrote:
> Good point, but I believe the critical thing here is not how long the
> transmission is but rather how long the listening period is.
>From purely probabilistic arguments, you would want the "duty cycle" to be as
>large as possible (more transmission than dead time).
But you also want the call itself to be short to reduce the latency to the next
QSO.
Ergo, short calls, repeated often. But the dead time needs to be long enough
for a slow poke to respond (especially in the Roundup). So too short of a call
is not productive either (since the duty cycle will be low).
I have seen CQs that are repeated for three lines before the station comes up
for air. Great in terms of attracting people but poor in terms of actually
getting someone to wait long enough for the CQ to end!
In practice, you also have other factors governing a short call. Carriage
Return/Line Feed characters start reducing the "efficiency" of the short calls
(the amount of time your callsign appears per second). You also want to send a
150 msec or so steady Mark tone (many software modems already do this) at the
start of a transmission to flush any phantom start bits the receiver may have
picked up before the transmission actually begins; that too will reduce the
efficiency of calls that are too short.
I think the right balance is to first determine the "dead time" you want to use
(i.e., how slow do you think the slow pokes are), and then try for a duty cycle
that is 50% or more. Maybe. (As long as your rig/amp does not melt from
excessive duty cycle. :-)
IMHO, if you are not already the top one or two contesters, I doubt
micro-optimizing will help any.
Moreover, all the micro-optimization is ruined by someone who answers you by
sending his calls 5 times and including your call twice. Then proceed to send
you a bunch of dots and his QTH and dog's name. I think you get more of that
in the Roundup than in other contests.
With more people using waterfalls to tune, you don't need long calls. They
will find even very short calls. And when a "RTTY Skimmer" becomes public, all
this becomes more moot. (You will definitely need an SDR of some form to use
an "RTTY Skimmer." You can barely fit 4 or 5 stations in a normal rig's 2.4
kHz passband.)
73 es HNY
Chen, W7AY
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