Packet radio

Packet radio is a digital radio communications method used to send packets of data. Packet radio uses packet switching to transmit datagrams. This is very similar to how packets of data are transferred between nodes on the Internet. Packet radio can be used to transmit data long distances.

Terminal Node Controller 2400 packet radio modem

Packet radio is frequently used by amateur radio operators. The AX.25 (Amateur X.25) protocol was derived from the X.25 data link layer protocol and adapted for amateur radio use. Every AX.25 packet includes the sender's amateur radio callsign, which satisfies the US FCC requirements for amateur radio station identification. AX.25 allows other stations to automatically repeat packets to extend the range of transmissions. It is possible for any packet station to act as a digipeater, linking distant stations with each other through ad hoc networks. This makes packet radio especially useful for emergency communications.

Packet radio can be used in mobile communications. Some mobile packet radio stations transmit their location periodically using the Automatic Packet Reporting System (APRS). If the APRS packet is received by an "igate" station, position reports and other messages can be routed to an internet server, and made accessible on a public web page. This allows amateur radio operators to track the locations of vehicles, hikers, high-altitude balloons, etc., along with telemetry and other messages around the world.

Some packet radio implementations also use dedicated point-to-point links such as TARPN. In cases such as this, new protocols have emerged such as Improved Layer 2 Protocol (IL2P) supporting forward error correction for noisy and weak signal links.

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This article uses material from the Wikipedia article Packet radio, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.