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Advanced GPS/APRS Digipeating
+ Note: This section assumes you are familiar with GPS, digipeating, and APRS
(each topic is discussed elsewhere in this manual). For details about APRS
(A Packet Reporting System) developed by Bob Bruninga, WB4APR, consider
obtaining a copy of “Getting On Track with APRS,” by Stan Horzepa, 157 page
paperback, published in 1996 by the ARRL, 225 Main Street, Newington, CT
06111.
Amateurs are using GPS receivers, a packet unit, and an FM transmitter to report
the location of their vehicles or stations to others. Their broadcasts use one-way
(unproto UI) packets, reporting call sign, latitude and longitude. Packet stations
hearing these broadcasts can monitor the location of the vehicles.
A common goal of these position reporting stations is to digipeat a UI packet
over a wide area (or a long distance), while moving though areas where the local
callsigns may be unknown. An effective solution for not knowing local callsigns
is to establish standard generic callsigns for digipeating stations and then use
these names in digipeating paths. Of course, this requires the acceptance and use
of standards for naming and using digipeating stations, by both the position re-
porting stations and the digipeating stations.
+ Common standards have been established by some local APRS groups, with
names such as RELAY, WIDE, and TRACE. We encourage you to contact your
local GPS (or APRS) interest group before configuring your TNC with its new
digipeater capabilities. Usage may vary by area.
Improving Efficiencies of Advanced Digipeating
As described above, mobile location reporting stations are using digipeating
paths containing generic digipeating names (e.g., RELAY, WIDE, TRACE) to
extend their range of reporting. Using generic digipeating enables a mobile sta-
tion to use the same digipeating path as it moves around, since there will (pre-
sumably) always be nearby GPS/APRS digipeating stations with one or more of
these generic names to pick up transmissions (i.e., UI packets) and re-transmit
them to a wider area.
Using generically named digipeaters does result in wider coverage of GPS sta-
tions, but several inefficiencies may arise from this common practice (depending
upon the availability and names of the digipeaters).
Modes of Operation GPS NMEA Interfacing Capability
User’s Guide 170 KPC-9612 Plus v 8.2