APRSNET.txt                 APRS ON LANS


     APRS can be operated in a multi-station environment so that many
PC's on a network can see the APRS tactical picture being maintained
by one MASTER APRS PC.  Typical applications would be a company where
many people throughout the organization need to see the location of 
their mobile units.  

APRSNET is the master program for running APRS on a distributed
local area network.  It is connected to your communications system
via a Terminal Node COntroller (TNC).  APRSnet parses all radio
traffic looking for position reports and other APRS formatted
data.  It builds a complete tactical picture including all of the
standard APRS displays and periodically it copies all of this data
into a master file on your network.

Throughout your organization, multiple APRSlave programs can access
this data and display it to other users.  To maintain data integrity,
APRSlaves cannot update nor modify the APRS data on the network,
although they can manipulate their own screens as needed.


INSTALLING APRSNET and APRSlave.

1)  Create an APRS directory on the PC which will serve as the master
station for APRS.  Change into that directory and use PKUNZIP -d to
unzip APRSnet.zip into that directory.  The -d option assures that
all of the APRS sub directories will be created as needed.  Next use
PKUNZIP -d again for the XmapsVV.zip file for your area.

2)  At this point, APRSnet.exe should be executable.  Set it up according
to the normal setups for APRS.  Next determine what path you will use
for storing the master file in a public access area on your network
and how often the file needs to be updated.  Typically 10 to 20 minutes
for VHF and 15 to 60 minutes for HF.  Enter this path name and
periodicity when prompted. 

3)  Have your network manager authorize WRITE access for your Master
station PC for the APRS.dat file.  All other stations should be
authorized READ ONLY access.  All stations will need READ/WRITE access
to the USER.LST file.

4)  Before any of the APRSlave stations will operate, you must first
prepare the file USER.LST using any DOS text editor and store it on the
network using the same path.  A sample USER.LST file is included on the
distribution which will permit three USERS, currently named SMITH, JONES  
and NOSEY.  This file will work with the COMPANY NAME of DEMO.  The first 
line of this file contains the USERS AUTHORIZATION number and all 
remaining lines contain the list of authorized users in the following 
format:
              Authorization#
              USER1.... 10/27/95 10:19:40
              USER2     10/27/95 10:19:40
              USER3     10/27/95 10:19:40
              ....      ....     ....
              reserved  ........ ........

You may list as many users as you like up to the number of users
registered in your APRS software license.  If you are currently using
fewer APRSlaves, then include dummy entries for future expansion.

5)  After APRSnet has run for a while and has begun saving the master
file on the network, then you may begin to run copies of APRSlaves.  You
will need to provide the following information to configure each copy of
APRSlave:
               Company Name - Same as callsign of Master station 
               User ID      - Identifies user. ie: Smith, Jones, etc
                              These names may be up to 9 characters long
                              without spaces
               NetPath      - Path to public APRS area
               Update Rate  - Periodicity for updating.  It should be
                              greater than the periodicity for APRSnet.
                             
After entering this data, be sure to use the alt-S Save command to save a
configuration file (CfigNET.apr) on this users PC.  With this file, his
copy of APRSlave will start up and load the APRS.dat file automatically.


OPERATIONS:

    The only parameter that has much effect on the system is the
periodicity.  Usually the APRSlave stations do not need instant data,
so the periodicity is a tradeoff between data latency, number of users,
and wear (if any) on the file server.  The rule of thumb is to make
the periodicity at least 5 times longer than the number of APRSlaves
TIMES the time it takes to download the file.  This assures a minimum
of collisions.  I have added an UPTIME and DOWNTIME parameter so that
the system can drop back to a minimum tracking level during off hours.
This minimum level is 20% of the normal level.

    APRSlave stations typically run APRSlave only when they need a
fresh look at the network.  After use, they automatically save a local 
copy of the BACKUP.BK file before they quit the program and go
on to other things.  If they attempt to re-run APRSlave before the
normal periodicity, the system will think that other copies of APRSlave
are running and it will just reload from the BACKUP instead of the
network.  If they leave APRSlave running, then the program
will continually get updated at the established periodicity.  After
each update, the slave station will always re-draw the map.
