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README.BBS
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1993-05-25
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INCLUDING APRS PROTOCOLS IN BBS and NODE SOFTWARE
This information is intended for BBS SYSOPS and the writers of BBS and NODE
software. Please consider the following advantages to including APRS protocols
in your station operation.
Since APRS allows stations to see the network topology in real-time, it is
ideal for determining the locations of all neighboring BBS's and NODES. If
BBS's and NODES simply included the 19 characters of LAT/LONG in a periodic UI
frame, all users could see geographically where the system is located. For
permanent fixed sites such as BBS's and NODES, this beacon could probably be
transmitted once every hour or so. The exact format of the UI frame should be
as follows:
BBSXX>APRS:!DDMM.xxN/DDDMM.xxW/comments as desired to end of line
For BBS code writers, this process can be enhanced by making the BBS
respond to APRS Query packets. One of these packets is transmitted whenever an
APRS station initializes his program. On receipt of an APRS Query packet, all
stations on frequency set a one minute random number timer and respond sometime
in that minute with their location. This way, any APRS station can obtain the
location of all stations on the frequency within one minute of comming on
frequency. The format of the APRS Query packet is W4XYZ>APRS:?APRS?. By
including the code in NODE and BBS software to respond to APRS Querys, the
periodicity of the APRS position beacon can easily be set quite infrequently
since stations can request the BBS position at any time.
I have one other request to BBS SYSOPS. Since APRS contains a packet
BEACON parser to display to users all BEACONS heard on frequency, this is an
excellent way for stations to capture MAIL-FOR beacons. In this way, APRS
stations simply call up their LATEST BEACONS display and see if there are any
BBS's reporting mail for them. Unfortunately, the parsing algorithm in APRS
only recognizes BText which occurs on the same line as the packet header.
MAIL-FOR which is listed on a new-line after an ID Beacon do not show up in the
APRS system. Only the ID portion of the packet is retained. For this reason I
would like to request BBS SYSOPS to modify their MAIL-FOR beacons to keep the
beginning of the MAIL-FOR list on the same line as the packet header. By
allowing APRS stations to check for mail without even logging on, you are
helping reduce congestion on the channel. Presently, most stations do not see
MAIL-FOR beacons because they scroll off the screen too rapidly. APRS grabs
all BEACONS heard and retains them.
Please play with the APRS software and load some of the backup and
demonstration files included. I'm sure you will find APRS to be an exciting
new capability for packet radio which can make packet radio much more
responsive in real-time communications.
Finally, ambitious code writers could add code in their BBS's to capture
all APRS position reports heard on frequency. These reports could be retained
in a file and be made available to local users. One of these files, if
downloaded, can be loaded by APRS users to display the locations of all
stations ever heard on the frequency!