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[aprssig] APRSdos Dead Reckoning of a Marathon

Robert Bruninga bruninga at usna.edu
Wed Mar 9 14:40:11 UTC 2005


>>> jim at stuckinthemud.org 3/9/05 2:23:50 AM >>>
>Can an APRSdos-generated object follow a route via a 
>number of preset "waypoints"?

Actually it follows a route layed out on the map using the
mouse.  Just draw the route of the event on the map using 
a purple colored line (using the MAPFIX utility).  Then
any object can be placed on the "route" and if "Follow" is
selected, then that object will begin to be deadreckoned 
around the course at its given speed.  It will transmit its
position once a minute.

See the map of the Annapolis 10K where we use this 
technique all the time.  We only use one tracker, and it
is on the TAIL bike which is unpredictable:  All the other
runners we track are objects and with APRSdr it is mostly
automatic.

http://www.ew.usna.edu/~bruninga/aprs/aprsdr.gif

I usually give the lead runner a speed of 9 kts, the lead
female about 8 kts the main pack as 7 kts and slow
ones on down.  Then just stit back and listen.  As 
checkpoints report the passing of an "object", then 
if my DR is off, I simply click-move-click to update him
where he actually is.

Is this real?  Is this accurate?  Good-enough, you betcha.  
Since most trackers are only on 1 minute updates too, the 
displayed position of even a tracker is as much as a minute 
off which is over  1/6th of a mile.   Normally we may only 
have to update the position a few times.  The LEAD always
crosses the finish line in 2.2 hours or so which is about
9.5 kts. 10 kts for world class.

And only one station (the DR station) needs to run APRSdr.
Everone else can use any flavor of APRS they want to view
the event.

We have been using APRSdr and one tracker for the tail 
since about 1996 or so, I think...

de WB4APR, Bob





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