Other Suggested Ideas For Software Writers!
Don't let me have all the fun. There are lots of additional utilities and
other neat applications for APRS waiting to be written! Please consider
taking one of these on...
WIDE-N UNIVERSAL DIGIPEAT MODE!
This may be the simplest mechanism for making an order of magnitude
improvement in APRS status and position reporting networks. In a WIDE-N
network, each WIDE digi simply repeats ANY packet with the VIA address of
WIDE-N; but ONLY ONCE. It subtracts 1 from the SSID and then keeps a
copy of the last 30 seconds of packets (or just a checksum of each one),
and compares each new packet that it hears with the LAST ones that it
digipeated. This way it avoids TRANSMITting it again! This simple
algorithm could tripple APRS throughput and double the number of routine
digi hops! See DIGIS.HTM.
LEVEL FOUR UI FRAME ROUTING!
There is a real nead for LEVEL-4 distribution of APRS UI frames through
a network. A UI frame addressed VIA XXXXX should be routed by any NODE that
hears it to the final NODE named XXXX. (It should already know the path!)
There, at that final node, the UI frame is transmitted ONCE (or maybe twice
some time later) as if it had been originated locally. See DIGIS.HTM.
PRE-EMPTIVE DIGIPEATING (this idea may be OBE if the "ALL"net idea works)
Until we get level-four routing of UI frames, it shuld be possible to
modify TNC code for pre-emptive digipeating. This means that a digipeater
will look for its callsign ANYWHERE in the digi-calls list in a packet header
and if it finds itself, it will go ahead and digipeat the packet and cancel
all of the earlier digipeat bits. This way a mobile only has to provide
a list of DIGI calls in the fartherest sequence that he may travel, and his
packets will all arrive at the last one in the list, no matter where along
the string he is located!
AUTODF NETWORK
In TNC code for these special APRS nodes, there should be room to add
an A/D reading or receiver signal strnegth and then transmitting that in
an APRS OMNI-SIGNAL-STRENGTH DF format. This way, each APRS digipeater
site, could also be used as an OMNI-DF site! See the DF.HTM
CALLSIGN and POSITION DATABASE NETWORK SERVER
Since APRS includes the single station QUERY format for requesting a
station to respond with his position report, there is no reason why any PC
interfaced with the HAMCALL CD ROM could not listen for such QUERYS, and
respond with a properly formatted APRS POSITION report for that station!
APRS QUERIES
One other addition to complete the APRS
philosophy, is to have the TNC respond with both its LText and BText
randomly within one minute of seeing an APRS query; a UI frame to the
address of APRS with the text field set equal to ?APRS?. This way,
stations could drop back to a decayed beacon rate of once every 4 hours or
so, but still would pop up on an APRS map if requested.
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Bob Bruninga
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Steve Dimse