Simply stated, Packet Radio is digital communication between
terminals and/or computers using radio as the transmission
medium. It is usually done with small home computers such as
the IBM PC but can be anything as simple as a dumb terminal or
as complex as a 370. The only requirement is that it have an
RS-232C interface.
The terminal or computer RS-232C interface attaches to a
Terminal Node Controller (TNC). The other side of the TNC
attaches to a radio. This could be any radio, not just an FM
radio. Although I don't know of anyone who has tried it, I see
no reason that a CB radio would not work (I don't know what the
legality of this would be).
The usual mode of operation involves two stations communRadio and using a modem.
In fact, part of the TNC is a modem.
Many such conversations could be taking place on the same radio
frequency at the same time. A system involving Carrier Sensed
Multiple Access with Error Detection (CSMA/ED) is implemented in
the TNC. This keeps the stations from interfering with each
other most of the time and when they do interfere, it detects
that fact and causes re-transmission. A check-sum at the end of
each packet insures that all data exchanged is error-free.
Addressininteractively with the entire group.
Most current activity is among Amateur Radio operators using
frequencies assigned the Amateur Radio Service. At first this
was done using a Special Temporary Authorization (STA) from the
FCC. The Amateur Radio rules and regulations have since been
amended to provide for this mode of digital communication.
Small home computers such as the IBM PC but can be anything as simple as a dumb terminal or as complex as a 370. The only requirement is that it have an RS-232C interface.
The terminal or computer RS-232C interface attaches to a
Terminal Node Controller (TNC). The other side of the TNC
attaches to a radio. This could be any radio, not just an FM
radio. Although I don't know of anyone who has tried it, I see
no reason that a CB radio would not work (I don't know what the
legality of this would be).
The usual mode of operation involves two stations communicating
just as they would using modems and telephone lines. From the
users standpoint, thereon (CSMA/ED) is implemented in
the TNC. This keeps the stations from interfering with each
other most of the time and when they do interfere, it detects
that fact and causes re-transmission. A check-sum at the end of
each packet insures that ala group of stations to converse
interactively with the entire group.
Most current activity is among Amateur Radio operators using
frequ and UHF bands have also been used with similar
results. 1200 baud has been the usual data rate on these bands
using unmodified voice-grade radios.
There has recently been a substantial increase in Packet Radio
actia high altitude
where it can be used as a repeater with coverage of almost
one-half the earth. Amateur radio operators using their home
stations have been using this satellite to comn interesting way of combining two
