[RTTY] Suggestions for RTTY RU

[Kok Chen]

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