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[aprssig] Dead Reckoning in APRS

Robert Bruninga bruninga at usna.edu
Sun Jun 18 01:09:17 UTC 2006

>> 1) There is always a small circle at the exact reported position.
>> 2) Then a bright line connects to the estimated "present position"
>> 3) Then the estimated DeadReckoned symbol is BLUE instead of 
>>     the normal color attribute.
>OK... it sounds like it is well implemented, better than I was visualizing 
>it. I would probably disable dead reckoning if it was possible, but 
>it might be nice to have it as an option.

Yes, in APRSdos it defaults to ON, but one can turn it off, though it 
always comes back on when you restart the program since it is 
considered sovaluable for letting viewers instantly assess the latency of 
their displays.  For example when the radio trips off line, then ALL the
DR'ed positions start extending all over, and you instanly know that
almost everytiing is growing stale and something is wrong.

Those of us that are used to seeing this multi-dimensional represetation
of the passage of time, space and distance on each mobile symbol or
weather object feel very blind when we dont have it.  When I see a 
fixed-color-ICON on a map for a mobile or WX object without Dead 
Reckoning, I always wonder how old that posit is, a minuite? 30 minutes? 
a Day?, A week?

Though at least most programs fade them to gray after the
recommended 80 minutes I hope.


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