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2 ENJOYING APRS (by BOB BRUNINGA, WB4APR)
2 ENJOYING APRS (by BOB BRUNINGA, WB4APR)
2.1 APRS Overview
The TH-D74A/E APRS / D-STAR handheld transceiver is the latest in the long series of
KENWOOD APRS radios and it brings the whole new dimension of digital voice (D-STAR)
that not only allows the internal global data and messaging by callsign (APRS) but now
global Voice by callsign through D-STAR networks. It is hard to fully grasp what this power
can bring to Amateur Radio operation once these radios are in the hands of the motivated
operator and experimenter. The radio continues the evolution of the fundamental principles
of APRS as a common information resource channel for facilitating human-to-human
communication and now voice. To see how this fits in, it is first necessary to understand
the history of APRS and packet radio.
2.2 Packet Radio History
The roots of the Automatic Packet Reporting System (APRS) go back to the late 1970s as
the AMRAD (Amateur Radio Research and development) Group was excitedly beginning to
experiment with AX.25 packet radio. This was before the Internet, and as we spent our
free time in our shacks, we were in fact all socially-networked by the AMRAD voice repeater.
On evenings and weekends, someone was working on something or developing something
new and sharing the excitement with the others on the repeater channel. We hung onto
our handheld transceivers everywhere we went like kids these days hang onto their iPads
and smartphones to keep up with the excitement.
Since only RTTY was legal in the USA at the time, we developed a RTTY chat channel to
augment our repeater communications. We wanted a digital channel that worked just like a
voice repeater. That is, anyone who had info transmitted it, and everyone monitoring
captured it. Advancing from RTTY, AMRAD developed the AX.25 spec and as soon as it
was legal, we were on the air as a chat group using real-time Unconnected Information (UI)
packet messaging. One field activity of this technical group was the annual
The History of APRS from VIC-20 to TH-D74A/E
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