ALTNETS.TXT ALTERNATE NETS USING APRS RESOURCES Document version: 8.4.3 23 FEB 1999 Author(s): Bob Bruninga, WB4APR ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ APRS normally ignores non APRS packets by looking only for 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. This is front end filtering helps minimize processing unwanted 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.