Date: Thu, 12 Apr 2001 

From: Bob Bruninga, WB4APR

To: TAPR APRS Special Interest Group <aprssig@lists.tapr.org>

Subject: TX-Cycle Recommendation?



> What is the recommended TX cycle (time between TX frames)?



It depends!



When we launched PCsat NO-44, the routine objective was for each

traveler or station needing satellite connectivity to get at least ONE

position/status packet via the bird per 12 hour period.  (On the NEXT pass

if the urgency is higher than routine).  With the terrestrial linked

global infrastructure this is completely sufficient for the mission.



The ISS experiment is not dedicated to APRS, but shared with other UI 

packet users worldwide.  For an automated position/status, (remote 
traveler) I see no need for more than one success per pass.  In this case
a 2 minute beacon will give youat least 4 chances at success on the 
congested channel.

For un-attended status/presence beacons, the goal should be one a day.  
With 6 passes per day, then about 1 transmission per pass is about right.
This translates to one packet every 5 minutes.





On ISS, We hope that after the initial excitement, that things will settle

down into a healty routine where everyone gets their small one second

chance to be seen... and then lets someone else have  a go...  We want to

see schools with kids watching to have a good chance at success on every

pass. Define success as ONE PACKET and your chances go way up...



By encouraging everyone of us to stay low key, then this helps assure each

of us that there may be more bandiwidth available when WE do our own

little school or public demo..  If you are doing a demo, please include it

in your status so all can see.



de WB4APR, Bob