ALTNETS.TXT ALTERNATE NETS USING APRS RESOURCES =========================================================================== Document version: 8.4.3 Document dated: 23 FEB 1999 Author(s): Bob Bruninga, WB4APR 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.