APRS

APRS is a system developed by Bob Bruninga, WB4APR, which uses amateur radio equipment along with a Terminal Node Controller (TNC) or similar device to transmit position reports, weather station data, National Weather Service Watches and Warnings, and short text messages between users.

It operates similarly to standard 1200 baud packet but has extended and specialized functionality depending on the TNC type and version and/or the software used. The national APRS frequency is 144.390 on the 2 meter amateur band.

The system is comprised of home users, mobile and portable users, and standalone digipeaters. Digis and home users that are immobile do not require a GPS unit to operate, rather the latitude and longitude coordinates can be manually imputed into either the TNC or the APRS software. Mobile stations operate using a GPS unit that can constantly update location coordinates, altitude, and speed to be transmitted into the APRS network. Standalone digipeaters operate on mountaintop locations and serve as the major supporters of the APRS network and are assigned the WIDE alias. All other stations regardless of altitude or location are assigned the RELAY alias.