Suggestions for using PBBSs
and for
including APRS protocols in BBS and NODE software

One thing we have learned in maintaining an operational APRS net on 145.79, is that it is very useful for all stations to include in the comment field of their position report the address of their home BBS! Then any station on the APRS frequency immediately learns how to send that station a lengthy packet message. If your TNC supports an internal BBS, it is also useful to leave it on and include its unique address or SSID in your comment field so that others can send you messages on your PBBS even while you are running APRS! A few stations sending keyboard messages into a PBBS on the APRS frequency is not objectionable since the number of packets are small and at typing speed. Also, the PBBS owner then DOES NOT read his mail over the air! I encourage all stations to operate their own PBBS maildrops on the APRS frequency; but please do not use the PBBS's to post messages for OTHERS who must READ the message over the air. All stations should avoid any other general computer to computer exchanges which would block the frequency for large blocks of time.

The remainder of this file is intended for BBS SYSOPS and the writers of BBS and NODE software. Please consider including an APRS posit in your beacons so that everyone can see the topology of your network. The !LAT/LONG format can be placed anywhere in the BText as follows:

    BBSXX>BEACON:!DDMM.xxN/DDDMM.xxW[PHGxyz/comments as desired...
                                  [this left bracket is the APRS BBS symbol
                                   * see PROTOCOL.HTM for exact formats
    BBSXX>APRS:[GRidsq]Comments to end of line

For BBS code writers, this process can be enhanced by making the BBS respond to APRS Query packets. On receipt of an APRS Query packet, all stations on frequency set a one minute random timer and respond sometime in the next minute with their location. The format of the APRS Query packet is W4XYZ>APRS:?APRS?. For those concerned with physical security, the grid square position report can be used which is ambiguous to 3 miles or so instead of the LAT/LONG posit accurrate to 60 feet.

MAIL-FOR BEACONS: Since APRS captures all BEACONs, be sure to transmit all MAIL-FOR info on the same line as the packet HEADER. Be sure the BEACON is transmitted to one of the standard addresses that APRS parses: BEACON, APRS, ID, CQ, QST, etc..

BBS POSITION DATABASES: Finally, include APRS position files on your system for all DIGITAL assets in your area. This way, anyone can load them into APRS and see network topology. THis process is facilitated now by the TAPR Northa Americal Digital Database which includes lat/long and APRS formatted files.

BBS FORWARDED POSITION REPORTS: It could be poosible to use the BBS forwarding system to ship APRS position reports from long distance travelers back home say on a once-a-day type basis. Imagine that this mobile station simply posts a message on any nearby BBS which contains his position and the routing for his home BBS. That packet message would be forwarded via the normal BBS network and arrive at the intended destination whereupon the destination BBS would in turn send out a decaying APRS POSITION beacon reporting that unit's position even if he was thousands of miles away and on the road! The format for such a position report for WB4APR might be as follows:

Send:    SP APRS @ WB3V.MD.USA                    Send command with Routing
Subj:    APRS Posit
Msg:     !3858.11N/07629.11W/040/010/Be home at 1200 Saturday.               

On receipt of such a message, the receiving BBS (WB3V) would form an APRS station reporting UI frame and transmit it periodically as follows:

WB3V>APRS:WB4APR   @051937/3858.11N/07629.11W/040/010/Be home at 1200 Saturday

As with all APRS packets, this packet would be transmitted once, then one minute later, then 2 minutes later, then 4 minutes later and so on. This doubling of the packet period after each transmission decays very repaidly to only 4 packets in the first 10 minutes, 3 more in the next hour and only 3 more in an entire 24 hours! This is not such a load! This would only be 8 packets in the first day and only 1 in the second! When the period is greater than 24 hours, the message is deleted from the system.

BBS POSITION DATABASE: Since APRS includes an individual station query capability, a BBS that has accumulated the position of all of its users, could respond to such an APRS query with a one time position report for that station without even logging on. The APRS query is simply a one line APRS message from the querying station to the Queried station with the letters "?APRS" in the first 5 character positions. A BBS with a callsign data base seeing such a packet could respond immediately with a position report for that station! The APRS station would see the position on his map!

Return to Table Of Contents

Mail comments/corrections on content to Bob Bruninga and on HTML formatting to Steve Dimse