MARATHON.txt 7.6b       APRS at the Marine Corps Marathon 1993,4 & 5

1995:  Had fewer GPS trackers and relied almost entirely on the DReckoning 
in APRSDR.EXE to move the LEAD, PACK and TAIL objects along the marathon 
route without operator intervention except when needed to correct for long 
term drift between the runner and the Dead Reckoned object. The LEAD runner 
goes about 9 Knots and the Tail goes about 4 Knots.  Also, these tracks DO 
follow the exact course, (this is in contrast to actual GPS vehicles which 
often cannot follow everywhere that a runner can go.  We also DR'ed the 
lead Handicapped, Woman, Special-Olympics and PACK.  See DR.txt.

MASTER-SLAVE.  This year we also operated three 486 color laptops
and two larger VGA displays all connected to the single APRS TNC.  Only one
laptop was operated by the APRS operator as MASTER, and all other laptops
were placed in SLAVE mode in front of the other voice net controllers, so 
they could independently zoom in to areas of their immediate interest.  If
we had had more VGA monitors, each laptop could have also driven an extra
large display.  The small size of the laptops fit unobtrusively at the
operating positions.  See OPS.txt.


APRS LESSONS LEARNED @ MC Marathon, 1994!
14,000 runners, LOTS of hams, and our second year with APRS!  In 93 we put
GPS on the LEAD, LEAD Handicapped, & TAIL chase cars. It was great, but 
predictible.  This year we let APRS dead-reckon the predictible movements
of the chase cars and built 11 Trackers for the ambulances.  Lessons:
 * Completely "sealed" GPS/TNC/Radio boxes should have drain holes!
 * Maritime GPS units withstand immersion in water. TNC's don't
 * You can't duct-tape GPS trackers to vehicles in the pouring rain
 * New Marine Corps Tents (made by lowest bidder) leaked everywhere!
 * 14,000 runners, vehicles, etc + RAIN = MUD
 * Mag-mount GPS trackers wont stick to aluminum HUM-VEES.
 * Tracking ambulances, which are parked for 99% of the event is BORING!
 * Ambulances with emergencies are under such close control by the ambulance
   direction net control, that he knows EXACTLY where they are anyway.
Of 11 units, 2 never quite got finished, one just couldn't be attached in the
rain, one leaked, flooded and died, the tinyest (running on AA cells) lasted
6 hours.  It rained from 5 AM until 1400.  Now for the good news:
 + We got double milage out of most APRS mobiles.  They put their GPS's in
   stand alone trackers for the ambulances, but kept their LAPTOPS and used
   the INPUT-MY command to manually report their position.
 + The alt-SETUP-MODES-sPecial command let the entire event operate on 
   145.79 while ignoring ALL other non-participating stations.  THis keeps 
   all APRS pages free of non-participants.   Many stand-alone trackers 
   are XTAL controlled, so you MUST plan on using the normal APRS freq 
   for special events.

CONCLUSIONS:  Next year, we will probably go back to tracking the high-
profile chase vehicles and HAM mobiles that are always moving, rather than 
ambulances.  

SUMMARY OF 1993 MARATHON!

     REPLAY MARATHON.hst to see how it went.  To make sense out of it all, 
try playing back only one mobile at a time, and turning Callsigns off.  
WB4APR-9 was the lead Handicapped vehicle (started 15 minutes early, 
W3ADO-9 was the lead runner, and MOBILE-9 was the Tail.  Statistically, 
we did very well.  W3ADO-9 was turned on at 0827 but did not move until 
0902.  It was removed from the vehicle at about 1127.  Transmitting at 
once a minute, there should have been 145 posits transmitted.  We counted 
about 115 in the file.  (many could have been filtered out by APRS as
duplicates).  The result computes to almost an 80% success rate!