[aprssig] AX.25 Digipeating precise timing?

[Robert Bruninga]

AX.25 experts needed:

We finished the Appalachian Golden Packet event with 15 hops to Maine and
14 hops back to Georgia.

At 9600 baud each packet is 0.5 seconds and we think we can increase
throughput significantly by totally changing our beacon plan, messaging
plan and getting the 2X benefit of 9600 baud.

This means we would like to better understand the exact AX.25 packet
timing.

I just timed 9600 baud packets between three kenwoods as digipeaters and
conclude an end to end packet with no collisions woiuld take about 8
seconds.  I want to analyze the probability of success with say a packet
starting at each end and meeting in the middle, what is the chance of
anialation of one, or both.  This depends on the delay that all
digipeateers (with Dwait off) will wait before transmitting.  It is only
during this window when a given digi, could hear two packets before it
transmits.

Anyone remember this stuff?, or am I starting from scratch..

Radios are set to TXD of 200ms...  But that is after the radio is already
keyed.

Bob, Wb4APR