The aprs.fi web service collects information from the Automatic Packet (or Position) Reporting System Internet System (APRS-IS). APRS is used by amateur (ham) radio operators to transmit real-time position information, weather data, telemetry and messages over the radio. A vehicle equipped with a GPS receiver, a VHF transmitter or HF transceiver and a small computer device called a tracker transmits its location, speed and course in a small data packet, which is then received by a nearby iGate receiving site which forwards the packet on the Internet. Packets are also retransmitted on the radio channel by digipeaters to enhance the coverage of the system. Systems connected to the Internet can send information on the APRS-IS without a radio transmitter, or collect and display information transmitted anywhere in the world.
