<><><><><><><><><><><><><><><><><><><><><><><><><> <> INTRODUCTION TO PACKET RADIO <> <><><><><><><><><><><><><><><><><><><><><><><><><> 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 hobbies, radio and home computers. Chuck Green - N0ADI ------------------------------------------------------------------- <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>