APRS-AT.TXT        APRS on the Appalachian Trail!
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Document version: 001
Document dated:   27 Nov 2002.
Author(s):        Bob Bruninga, WB4APR <bruninga@usna.edu>

Will need to add PHG manually to stations configuration.

APRS-AT was written to run in APRS Kiosks along the Appalachian Trail
wherever we can find power and a sheltered location for an old DOS PC.
APRS-AT runs under automatic control to report the movement of hikers
along the trial.  Hikers may either be HAMS with APRS portable gear,
or regular hikers who have placed themselves on the map at one of these
APRS Kiosks along the trail.  Their movements are dead-reckoned based
on their estimated speed and direction.

DEAD RECKONING and APRS:

Although all APRSdos programs dead reckon all moving objects to their
estimated current positions based on elapsed time since the last
position report, APRS-AT (derived from APRSdr) does this movement at
the point of transmission, not at reception.  Thus, to all other APRS
programs of any kind, they see the new estimated positions only.  This
includes the WEB FINDU.COM as well!

This is a very powerful technique which can provide the same measure of
tracking but without attaching a GPS to every hiker!  The concept is 
simple, the position of the hiker at least for the purpose of knowing 
approximaely what section of trail he is on is completely predictible 
from his last known point as long as he makes a reasonable entry of 
his estimated speed over the next section...

HIKER DATA ENTRY:  Each hiker is identified by his initials, direction
of travel and type of hiker (Day, Through, Weekend, etc).  He also
enters additional data that will show up in his object report:

  *Initials for ID     AAA
  *Direction           North or South
  *Type                Day, Section, Through, or Weekend
  Starting point       Where he entered the trail
  Destination          His ultimate destination
  ICON                 Hiker, Bike, Horse, Circle, Sqare, Triangle
  Speed                Speed in Miles per day...

The first three are used to give him his unique ID such as "AAANT"
for a north bound through hiker with the initials of AAA.

NIGHTIME OPS:  All such hikers are dead reckoned every hour or so 
between the hours of 7 AM to 7 PM.  After those hours, all objects 
are transmitted at their last predicted position and their ICON is 
converted to the "tent" icon.

Whenever an object has not been updated in a week or reaches its final
destination, it is removed from the system.

THE TRAIL:  The Appalachian Trail is added to a DOS map as a purple
line in the map file USA-AT.MAP.  This is one map that covers the
entire 2000+ mile range of the trail.  Just as in APRSdr, the trail
begins in Georgia and runs to Maine and BACK so that Hikers may be
placed on the trial going either direction.  North bound hikers use
LEG 1 and southbound hikers use LEG 2.

BEGINNING A HIKER:  The INPUT-ADD-OBJECT command in APRSdr has been
completely customized for APRS-AT.  The hiker only needs to enter the
appropriate information above, and he is placed on the map at the
present location of the APRS Kiosk he is using.  To make this work
the APRS-AT must be customized with these parameters:

  1) The location of the Kiosk
  2) The immediate direction of the first leg north and south
  3) The difficulty of the next 60 miles north and south

Whenever the destination of a hiker is reached, his SPEED is set to zero
so that no further DR occurs and his ICON remains in the system for a
day before it is deleted...

Hikers that APRS-AT is dead-reckoning will show in CYAN.  Any
other of your uplinked Objects will be the usual Yellow.


APRS-AT keeps the map USA-AT in memory at all times
4  APRS-AT will not let you zoom below 1 mile.  This is because the DR
algorithm fails due to map scale problems below that range.

See APRSdr.txt on how the USA-AT map is made using color 13 and no
leg is shorter than what a Hiker would cover in one hour (about
one mile)

REDRAW:  APRS-AT has an automatic recenter and redraw routine whenever
keyboard has been in active for 3 minutes.  This time is settable with
the alt-S-OTHER-REDRAW command.

By default, APRS-AT sets the special APRS ALT-NET of ATxxxx.  Thus this
software will only show the location of other APRS-AT systems.  But
since the Kenwood's cannot do alt-Nets, all Kenwoods showing the 
HIKER ICON will be displayed too.

VALIDATION:

APRSDR.exe must be registered to dead reackon more than one object.

