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[aprssig] A/N Football Run APRS Usage

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Mon Dec 8 18:23:20 UTC 2008


I've attached a .JPG of the APRS infrastructure used by the FBALL 
callsign across the Army/Navy Football run for 2008.  This JPG is very 
large, so you'll have to zoom in to see details.  There are definite 
gaps in the coverage of the run, and Bob's prediction (duplicate FBALLs) 
was true at several points early in the run, but dramatically messed up 
the picture late in the run.  The 2 FBALLs bouncing back and forth 
completely obscure the wonderfully detailed points of the run as it 
entered Philadelphia.

Black dots are the position reports from FBALL.  Black lines join these 
dots in time-order.

Red lines are direct reception of the FBALL call.

Green lines are are relay traffic from Digis to IGates.

Note that my graph generator only supports a direct or single-digi path 
at the current time.  If additional digis were involved, they will not 
be relfected in this map.

Lynn (D) - KJ4ERJ - Playing with alternate realizations of APRS data!

PS.  Background map supplied by http://openstreetmaps.org - Click the 
Export tab to pull a LAT/LON delimited section of map.  Excellent for 
UI-View use as well!

PPS.  Maybe if I rejected impossibly fast location changes, I could 
clean up the overlapping ping-pongs, but would it be the ping or the 
pong that should be retained?...

Robert Bruninga wrote:
> 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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>
>   

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