[aprssig] APRS CSMA Settings

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Tue May 20 11:14:29 CDT 2014


On 5/19/2014 3:53 PM, Kenneth Finnegan wrote:
> the competing CSMA
> behaviors are:
>
> 1. None. Transmit as soon as you have traffic
> 1a. Time slotting. Transmit during your allocated time slot (seconds
> since top of hour modulus beacon interval).
> 2. DWait. Wait for a specific period of quiet time before transmitting
> any pending traffic
> 3. P-persistent. Randomly transmit during a quiet time slot.
>
> Deaf trackers obviously must follow the first algorithm.
>
> Reading the archives, it seems that Bob, et. al usually promotes no
> CSMA (algorithm 1) for digipeaters as well, due to:

I used to think this as well because of some confusion in the words.  
Bob says that digipeaters should not wait before repeating a packet, but 
I have had him clarify that statement to mean that they should have a 
DWAIT of ZERO, but SHOULD wait for a clear channel before transmitting 
anything.

Bob, if I still have the worng (sic) please correct me.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32



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