ALTNETS.TXT       ALTERNATE NETS USING APRS RESOURCES
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Document version: 8.4.3
Document dated:   23 FEB 1999
Author(s):        Bob Bruninga, WB4APR <bruninga@nadn.navy.mil>
ABSTRACT
AEA.TXT           How to operate independent nets on 144.39 without
                  having to see everyone's traffic.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

     APRS normally uses a distinct series of general generic callsigns
in the TO ADDRESS of all packets.  These are calls commonly expected for
beacon and other UI packets addressed to ALL.  These calls will be
captured by all APRS stations (See PROTOCOL.TXT for the list).  All other
TO addresses are ignored.  This is a front end filter to minimize
processing unwanted or unneeded packets.  But this also allows stations
to operate SPECIAL and ALTERNATE nets on the same frequency without
seeing or appearing on everyone else's displays.

SPECIAL MODE:  THis command, alt-S-MODES-SPECIAL, tells APRS to ignore
ALL TO calls except SPCL and it configures your TNC to transmit TO SPCL.
This allows participants in a special event to ignore all other traffic
on frequency but still all non-participants will still see the SPCL
packets.  To allow Trackers to also run SPECIAL, there is a SPCxyz
construct that is similar to GPSxyz.

ALTNETS:  The command, alt-S-MODES-altNet, sets up APRS to operate
semi-privately so that you will only see other stations with the same
ALTNET callsign and no one else on APRS will see you either.

This ALTNET capability allows you to operate many independent and semi-
private networks all sharing a common frequency and digipeater
infrastructure.  Note, however, that it is *NOT* private in the sense
that others can disable their default TOCALL filters and can capture
your packets easily.  But in most cases they will not know you are there.

