INTRO -- Introduction to using N2YGK's street-level detail maps with APRSdos.

Introducing tig2aprs
--------------------
The DOS version of APRS (APRSdos) is a fairly complicated program to
use.  It is extensively documented.  Please spend a few hours reading
through the APRS\README\ directory if you haven't already.  Even
better, find a local elmer and have him show you the ropes.  Also,
check out the various APRS pages on the Internet (start at
www.tapr.org) or the new book, Getting on Track with APRS, by Stan
Horzepa, WA1LOU.

If you are somewhat familiar with APRSdos, it is possible that you've only
ever used the default MAPLIST, MAPLIST.USA, which gives a kind of overview
of the entire USA with not much low-level detail with the exception
of one or two areas like around WB4APR's QTH.  You may also have looked
at street-level detail maps produced from US Geological Survey 100K
Digital Line Graph (DLG) data using the MK100Kxx.EXE program.

The maps you have now are similar to the DLG 100K maps, but have been
generated using a different process from slightly different data.
A program called tig2aprs (by N2YGK) is used to process data from
the US Census TIGER/Line files (1995 version).  These are based on
USGS 100K DLG maps but have been augmented with names of places, landmarks,
and so on.

The big difference between maps generated by MK100Kxx.EXE and tig2aprs
is that tig2aprs comes close to fully automating generating a series
of hundreds of maps that give detailed street-level coverage of an
entire county.

Getting to Know Your Maps
-------------------------
The following is a step-by-step tutorial "tour" of a county's map files.
The sample county is Duval County, FL (one of the counties around 
Jacksonville).

Install the map files:

If you are lucky, you've already got the map files installed, or you've
obtained the NOFARS map distribution.  Please follow the instructions
with whatever map distribution you get.  I supply the maps to the person
who ordered them as 1.44 megabyte ZIP files.  You need the UNZIP utility
program to unpack these files.  Assuming you have UNZIP and it is in your
PATH, 

  a. connect to wherever you've installed APRS:

        cd \aprs                        

  b. unzip the maps, which are one one or more floppies:

        unzip a:fldumap1.zip maps/* maplists/*

     insert the next floppy,

        unzip a:fldumap2.zip maps/* maplists/*

Hopefully you've not run out of disk space and you now have a Duval
County map distribution installed.

Run APRS and explore:

   a. Fire up APRS in the usual way (the name changes each version):

        aprs77f

   b. If you haven't selected compressed text already, do so by hitting F7.

   c. Change your MAPLIST, using the "Map Change" APRS command. Type:

        M C du 

      Make sure to hit ENTER and then HOME.  You will now be centered
      on Duval County, zoomed out to the 16 mile range.

   d. Take a look at the borders of the maps in the "DU" maplist:
      Use the "Map Plot Borders" command:

        M P B

      and then hit F3 about 10 times you will see smaller and smaller
      "picture frames" drawn until they all dissappear.  Now hit F4
      about 10 times and all the frames will reappear, nested inside
      each other.  Each of those frames represents a single MAP file.

      Notice how heavily built-up areas like near the center of Jax
      are represented by many small maps, some as small as 1/2 mile
      range.  Other areas may be represented by 1 or 2 mile maps.
      This is because APRSdos limits a particular map to 3000 data
      points.  tig2aprs automatically tiles an area so that 3000 points
      can fit in a map.

   e. Zoom in a bit by hitting PgDn several times.  At a certain point,
      you will see one or more crosshairs.  If you center the "sight"
      (the round cursor) on one of these crosshairs (use the mouse or
      arrow keys) and then hit HOME, possibly followed by PgDn once more,
      you will be zoomed in to a more detailed map.  

   f. Repeat this, trying PgUp, PgDn, moving the sight, and hitting home 
      to get a feel for the maps.  Notice the various labels of places,
      shopping centers, water bodies, etc.  Also note the various symbols
      such as green buildings for schools, blue buildings for churches, etc.
            

The Fully-Overlapped Maplists
-----------------------------
The "DU" maplist has full coverage of the county, but you have to center
the sight on each map, or be zoomed in and pretty near the center or the
detail map won't display.  This is because the map is not displayed until
it completely covers the screen.

There are four additional maplists, DU1, DU2, DU3, and DU4 that cover
the NW, NE, SW, and SE quadrants of the county.  The reason four maplists
are needed is that APRSdos imposes a limit of about 170 maps per maplist.
Each of these quadrant maplists has fully-overlapped detail maps.

With fully-overlapped maps, if you are zoomed in to a range that is
1/2 the map range (to .5 mile in most cases), then you can center the
sight anywhere and you will always see the same level of detail.  As
needed, a new map will be loaded.  This comes in handy when you are
tracking a moving vehicle, for example.  Try this:

   a. Select the NE quadrant with the "Map Change" command:

        M C DU1

   b. Move the sight over to the vicinity of the St. Johns River, using
      the mouse or arrow keys and zoom in with PgDn until you get to
      street level detail.

   c. Pretend you are tracking a car by picking a road, move the sight
      along it, and hit Home every now and then.  Notice how every few
      times you do this APRS loads a new map.

   d. Get someone with an APRS tracker in a vehicle to drive around.
      Use the "P" screen, "hook" the callsign of the vehicle you want to
      track (by hitting ENTER when the site is on the row containing the
      callsign) and then select track with "T".  If you can't do this live,
      you can always replay an existing track history.  See "Files Replay."

