APRS

Automatic Packet/Position Reporting System

The Automatic Packet/Position Reporting System (APRS) was created by Bob Bruninga, WB4APR, of Maryland, USA. Bob Bruninga is the president of APRS Engineering LLC, which owns the trademark for APRS. Bob created the APRS protocol and developed a program called "APRSdos", which is the official name of "APRS". This program runs on the MS-DOS platform.

The idea of APRS came about in the late 1970's, and it has been constantly updated since its initial release in 1992. Today, many licensed versions have been released for many platforms. Versions include MacAPRS for the Macintosh, WinAPRS and APRSplus for Windows, javAPRS written in Java, and PocketAPRS which runs on the Palm III.

The APRS protocol uses packet communications which are Unnumbered Information (UI) frames. The packet contains the position, station data, status, and messages. The position contains the latitude and longitude, the station data contains the station's information (call sign, output power, etc.), weather information (temperature, wind speed and direction, etc.), etc. The status is like your comment and the message is like e-mail.

APRS is different from regular packet in three ways. First by adding maps and other data displays, second, by doing all communications using a one-to-many protocol so that everyone is updated in real time, and third, by using generic digipeating so that prior knowledge of the network is not required. AND FOURTH, since 1997, a worldwide transparent internet backbone, linking everyone worldwide. APRS turns packet radio into a real-time tactical communications and display system for emergencies and public service applications (and global communications). Normal packet radio has only shown usefulness in passing bulk message traffic (e-mail) from point to point. It has been difficult to apply conventional packet to real-time events where information has a very short lifetime.

Although the recent interfaces to the Internet makes APRS a global communications system for live real-time traffic, this is not the primary objective. But like all of our other radios, how we use APRS in an emergency of special event is what drives the design of the APRS protocol. Although APRS is used 99% of the time over great distances, the protocol will always be optimized for short distance real-time crisis operations.

APRS provides universal connectivity to all stations by avoiding the complexity and limitations of a connected network. It permits any number of stations to exchange data just like voice users would on a voice net. Any station that has information to contribute simply sends it, and all stations receive it and log it. Secondly, APRS recognizes that one of the greatest real-time needs at any special event or emergency is the tracking of key assets. Where is the Event Leader? Where are the emergency vehicles? What's the Weather at various points in the County? To answer these questions, APRS is a full featured automatic vehicle location and status reporting system too. It can be used over any two-way radio system including HAM, CB, Marine Band, and Cellular Phone. Now there is even a nation wide LIVE APRS tracking network on the Internet.

To enjoy APRS you require a transceiver with a Terminal Node Controller (TNC), and an APRS program that runs on a personal computer. 

APRS Display Symbols

APRS provides approximately 200 station icons which can be sent in addition to your station data. You can select and send whichever icon best suits your situation. The symbols are divided up into tables with various characters representing each symbol. In an APRS position report, the character following the latitude (North/South) is a table character and the character following the longitude (East/West) is the APRS symbol character. The table character selects one of two symbol tables or may be used as a numeric overlay over some symbols as follows:

View The Primary Symbol Table

View The Secondary Symbol Table