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[aprssig] A/N Footbal Run is underway!

Robert Bruninga bruninga at usna.edu
Fri Dec 5 18:22:37 UTC 2008


Army/Navy Football 128 mile Run is underway (Annapolis MD to
Philly, PA) and using APRS networking for situational awareness:
www.aprs.org/football.html

There are 3 Vehicles: CHASE-1,2,3 but the one doing TAIL duty
with the football changes his call to FBALL.  In the past 16
years, one van is FBALL all the way to minimize TNC coordination
issues, and at each shuttle update, all 12 mids or so have to do
a chinaese fire-drill from the shuttle van to the tail van so
the callsigns don't have to change.

This year, they wanted to try changing callsigns on the fly
(which I am sure will lead to problems!).  But we are going to
try it.  Using D700's we loaded CHASE-1,2,3 into PM's 1,2,3 and
FBALL into PM 4.  So each vehicle can change to FBALL easily,
and then back to his own CHASE-N number.  (you can see the
potential for confusing the tactical picture!)

Anyway, the potential issues will be:

1) two FBALLs, if someone forgets to change back

2) CHASE-N will become a dead SYMBOL at point X when he takes
over FBALL tailing duties and remain on the map to confuse
everyone until he is relieved later by another FBALL, then
CHASE-N will instantly jump to new mobile position.  

3) Of course, clients that display SYMBOL color attributes or
proper dead-reckoning will instantly recognize a non moving
stuck object after one minute without an update, but without
these visual clues, many PC and WEB clients do not distinguish
"live, moving, fresh" symbols from "old-stale-wrong" symbols to
the casual observer an dso casual map viewers often get a
completely wrong picture.

4) To change this abandoned callsign issue from a disadvantage
to an advantage, I briefed the students that this is a way of
MARKING on the map the position of the last vehicle change...
Also, we use client software with color and DR symbology
attributes at our key locations (not fixed icons) so they can
instantly recognize an abandoned symbol.

Here are some things to consider:

A) The POSITION-TEXT of all vehicles has the actual club W3ADO-N
callsign so that looking at the real call in the TEXT we can
still see which vehicle-N is actually acting as FBALL.  We can
also see if any CHASE-N's are using the wrong N.

B) If someone had time, the ideal thing to do would be to have
an APRS base station operator, to SELECT the abandoned CHASE-N
callsign and TAKE-it-OVER as an object.  THen do the KILL OBJECT
command to eliminate it from all maps.  When that vehicle again
resumes its callsign, then it will again appear on the map with
no further intervention.

This was a primary reason back in the early 90's when APRS was
designed, so that any operator can take over ANY station/object
symbol regardless of whether it is an object or station or item.
Unfortunately, some client software treats STATION and OBJECTS
differently, and will not let you take over an abandoned
"station" call and therefore have lost this powerful tactical
maintenance feature.

I'll be watching APRS prettly closely the next 10 hours.  The
run goes all the way to Philly to arrive at the game Saturday
Morning.

Bob, Wb4APR




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