MOBILE.TXT        TIPS FOR MOBILE APRS USERS
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Document version: 8.3.8
Document dated:   10 Mar 99
Author(s):        Bob Bruninga, WB4APR <bruninga@nadn.navy.mil>
ABSTRACT
MOBILE.TXT        Useful tips for mobile APRS users.
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NEW ITEMS:
* Ver 837 now has single finger moving maps.  Hit MAPS-arrowkey to re-
  center the map

* Ver 819 can estimate Mile Markers for most interstates in the USA.  
  Just hit MILE-MARKER-NC95-156, for example, and APRSdos will draw a
  line across the interstate 95 in North Carolina near MM 156.

* INPUT-MY-RADAR sets your airspace.  You can set ALARMS to go
  off on ANYONE, only SPECIAL stations, or only NEW stations.

OVERVIEW:  Although APRS on cars, boats and aircraft equipped with GPS
or LORAN is obvious, it is IMPORTANT TO NOTE THAT APRS IS STILL VERY
USEFUL FOR VEHICLES WITHOUT GPS TOO!  Actually, the only stations
that need GPS are the ones that are lost!  For this reason, the first
section of this file will discuss the use of APRS in a vehicle without GPS.

Note:  Be sure to do a MAPS-OVERLAY-DIGIS before going on a trip so you
can see where the digiepaters are...

MANUAL POSITION UPDATING:   Even without GPS, just use the map and the
INPUT-MY-POS command to enter yourself on the map.  If you include a course
and speed, then you will also move on everyone's screen by dead reckoning.
(unfortunately many new APRS clients overlooked the extremem importance
(of deadreckoning in APRS and objects don't move on their maps (sad)).
Depending on the speeds involved and the size of the net, updates are only 
required when there is a significant change to course or speed.  One 
station moving cross country reporting via HF set his course to 270 degrees 
and set in an average speed of about 50 MPH.  Although he only
updated his exact position once every few hours, because of the automatic
APRS dead reckoning, his van appeared to everyone to move west giving a
good approximation of his progress.

   Although we used GPS equipped bicycles during a 1993 marathon, we did 
not even bother in 1994.  We simply monitored the voice nets, and 
occasionally whenever someone mentioned where the LEAD, TAIL or
PACK runners were, the APRS operator simply updated the reported locations,
and all APRS stations along the route could see visualy where these objects
were, even without listening to the radio.  Additionally, since the course
is always known, and the speed of the runners in a marathon is very well
known, the dead-reckoned movement of these symbols between updates was
actually just as accurate as GPS!   See MARATHON.txt.  A special version
of APRS can actually deadreckon objects along a given course making all
the turns indicated on the map.  See APRSdr.txt.

MOBILE OPERATIONS:  APRS was designed to make mobile operations with one
finger relatively easy.  The following summarizes the commands that are
frequently used in the Mobile environment:

  G - GOTO:  On any screen other than the MAP, this command will redraw
      the map centered on your vehicle.  If you are already on the map,
      then GOTO puts the cursor on your station so that a single press of
      the PgUP/DN keys will allow you to zoom or home the map in one step.

  T - TRACK:  Select this on the P-list.  As a tracked station
      approaches the edge of any map, APRS will automatically re-draw the
      map in that direction.  If TRACK mode is on, then the GOTO command
      will go to the Tracked vehicle.

  A - ALARM:  Also activated on the P-list, will trigger BEEPs and cause
      your screen to be centered on the station if it moves.  Useful to
      alert me when the wife is coming home so I can go to the kitchen
      and look domestic on her return.

  IMP - INPUT-MY-POS: Use to manually update your position, or change your
       symbol, course, speed or comments.

Unless your exact location between point A and B is important, simply enter
your estimated average speed, and the straight line course to B.  This way,
other stations will be able to see your dead-reckoned progress toward B and
you will not have to make frequent updates.  Since APRS also DR's your
progress on your own screen, you will see the same thing that everyone else
sees.  You can tell whether you need to update your progress or not.  You
will notice, that on your own screen, each DR'ed position is posted at the
same time that a position report is transmitted by your station.  That is
why the reports will be close together initially and be spaced further and
further appart.  In order for this DR to work on your own screen, you must
not be in HSP or SPM modes.  See the ALT-SETUP-GPS-OFFgps command below.
If you want to see where your DR'ed position is at any time between transmis-
sions, simply hit the space bar, and a fresh DR will be displayed.


CHEAP AND PLENTIFUL 8086 LAPTOPS:  I prefer my old 8086 laptop monochrome
LCD since it works BEST in bright sun!  It only has dual flopies, but
a minimum APRS system PLUS DOS will fit on a single 720K floppy.  TO give
you some more maps, though, you might want to put only the APRS.EXE on
the system floppy in drive A and put all the rest of APRS and maps on
drive B.  Then boot with A, then change to B: and run A:APRSxxx.  This
will load APRSxxx.exe from A, but it will look on B for all its files.


AUTOMATIC GPS/LORAN INTERFACES

  See the GPS.txt file for information on the several methods for 
interfacing your PC to GPS or LORAN.  Some useful commands are:

    Alt-SETUP-GPS-TIMEsync - Synchronizes your PC clock to the GPS time
        in the next GPS posit heard.  This is important to avoid dead-
        reckoning errors on small area maps!
        NOTE that this command only synchronizes the minutes, so
        you at least have to be in the right hour....

    Alt-SETUP-POSrate - Sets both your own screen updates and the
        on-air transmission rates through the TNC.

    Alt-SETUP-GPS-OFFgps - Turns off the HSP/SPM modes without having to
        re-configure.  This is useful if you are normally configured for
        HSP or SPM modes but are going to be doing manual updating.  If
        the PC is left in HSP or SPM modes, then your local screen will
        NOT be updated on each DR.   IF HSP and SPM are off, then each
        time your position is transmitted, a new DR plot is drawn.

    OPS-COMM-GPS - Permits you to either communicate with your GPS if it
        has a bi-directional port, or to monitor the TNC.  This command
        also switches the APRS port-splitter circuit in HSP mode so that
        you could monitor the GPS.

    F6  This key is called the QRT function because it forces your speed
        to zero as you approach your destination so that your posits will
        not continue to dead reckon on everyone's screens after you
        turn your system off.

MAPLISTS:  As you enter different areas of the country, don't forget to
change to a new MAPLIST.xxx for each of the 6 major regions of the country
with the MAPS-CONFIG-CHANGEmaplist command.
