[aprssig] Improving Messaging and dytnamic Object management

[Robert Bruninga]

Doubling the throughput of Messages or dynamically managed
objects...

The original RETRY rate for APRS was 8 seconds for the first
RETRY, then 16, then 30, then 1 minute and so forth, doubling
the  period as the information got older.  But making the rate
HIGH for NEW info.

Many of the follow-on clones ignored this fundamental principal
and used brain-dead fixed rate retries, thus making messaging
and dynamic OBJECT management abismally slow and unresponsive.

This was compounded by overly conservative settings on
DIGIpeaters to block out ANY retries under 28 or 30 seconds.
Thus assuring slow response.

Finally some clients are starting to be re-written to include
the above original DECAY algorithm so that messages can move
more easily, so it is time to fix the digipeater network.  Hams
lead by John Ronan in Ireland have been experimenting with
setting the DIGI DUPE filter to 7 seconds instead of the usual
28 or 30 and have indicated no ill effects.

I Encourage hams in areas that want to improve the
responsiveness of APRS messaging and OBJECT management to
consider trying this setting and monitoring the channel to make
sure that it is still a sufficient dupe filter.  If long delayed
dupes are still a problem, then the next threshold would be at
14 seconds.

Bob, WB4APR