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[aprssig] Weather Stations and Net Neutrality

Robert Bruninga bruninga at usna.edu
Fri Aug 15 13:25:25 UTC 2008


>>> I'm surprised that smart beaconing hasn't made 
>>> its way to ...[weather]
>> 
>> MacAPRS implemented increased beaconing during 
>> rainfall... and it was in WinAPRS from the start 

And APRSdos used the fundamental decay algorithm on WX (like all
packets).  If the data was changing, then it was transmitted NOW
(the only exception was wind below some threshold).  If it was
no different than before, then the time to next beacon was
doubled.  This way, not only was traffic minimized during non
changing conditions, but as soon as something did change you got
an immediate packet and a higher update rate until it decayed
down again.

The Decay algorithm was fundamental to APRS.  New data is
refreshed quickkly, older data is refreshed less and less often.
This applies to EVERY packet, positions, status, messages,
weather, bulletins, whatever.  It was a big set back that so
many follow-on clients ignored this fundamental principal.

Fixed rates are an abomination to APRS principles.  They are
either too high and flood the network with redundant old data,
or they are too low and really-really delay new and important
information!  ARGH!!!!    And worse than that, the solution of
having the operator manually change rates from high-fixed to
low-fixed guarantees errors both ways.  Either rates too high,
or rates too low for the immediate need.

The Decay algorithm was fundamental to APRS.  The user had NO
settings!!!!  It worked for routine (decay rate decayed down to
30 minutes for old data) but then if you changed ANYTHING in
your packets, then the rate went back to an initial 8 seconds!
And doubled eery transmission after that.  Messages could really
fly..  (8 seconds to 1st retry) compared to a missed 1 minute
fixed rate which would take 2 minutes per line of text for other
clients at a fixed 1 minute rate.

Fixed rates were never intended to be part of APRS for changing
data.

Bob, WB4APR






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