Xastir—Open-Source Client for the Automatic Packet Reporting System

In the early 1990s, Bob Bruninga, an instructor at the United States Naval Academy in Annapolis, devised an interesting stunt: he wanted to track the Army/Navy game football on its travels from Annapolis to Philadelphia, about 150 miles away. To do this, Bruninga stuffed a small electronics package into a football helmet consisting of a GPS receiver, an Amateur Radio transmitter and a radio modem. At the time, GPS receivers were quite expensive (and a novelty), and cell phones still were quite new and incapable of doing data. Bruninga's real innovation, however, was to plot the received position reports on a computer map display and automatically track the position of the midshipmen carrying the game ball (see Resources).

That was one of the first uses of the Automatic Position Reporting System (APRS)—originally, Amateur Position Reporting System. APRS has evolved considerably in the decades since. The protocol has been greatly enhanced to include automated weather station reports, status messages and two-way text messaging. APRS communications systems have evolved beyond simple transmitters and receivers to sophisticated networks that encompass Amateur Radio satellites, digipeater (digital repeater) automatic relay systems and Internet gateways. APRS technology is not confined to Amateur Radio; it is used in numerous commercial applications as well.

APRS is intended to provide a situational awareness display or tactical display. Everything of note should be displayed easily on the map with additional detail and messaging available at a click. In emergency operations, a quick glance reveals what resources are available and where.

Note: APRS is a registered trademark of APRS Software and Bob Bruninga, WB4APR.

Imagine a map display on your laptop with moving symbols representing the current positions of your ham radio friends and acquaintances, while they can see your real-time position on their displays. Imagine being able to “instant message” any of them as well. These are a small subset of Xastir's capabilities, and they can be accomplished with a small amount of equipment and an entry-level Amateur Radio license (see sidebars).

Figure 1. Xastir Centered on Seattle, Washington (Maps Courtesy of US Census Bureau Tigermap Server)

Xastir is open-source software, which aims to be compliant with and interoperable with the APRS protocol. Frank Giannandrea, KC2GJS, wrote the first version of X Amateur Station Tracking and Information Reporting (XASTIR) for Linux and released it under the GPL license. As with many open-source projects, even though Frank has retired from the project, a team of developers has continued and considerably extended Frank's original work. Xastir is arguably one of the most capable APRS implementations and has an active user community.

Xastir can be compiled and run on Linux, FreeBSD, Mac OS X, Solaris, HP/UX and even Windows. Today Xastir can display objects and their associated status (and messages) in real time on Internet-based or local maps, enable two-way messaging between stations and many more functions. Some Xastir users are involved in search and rescue (SAR), others in helping out at public service events or Amateur Radio emergency organizations, but many use it just for fun.

You can get started in Xastir with Internet-based maps and data streams. Advanced users have radio interfaces connected to laptops or touchscreen trunk-mount PCs in their vehicles where it gives a tactical display of nearby stations while providing mobile mapping and letting everyone know their current position. Xastir also can speak via the Festival speech synthesizer.

Note: although Xastir is described here as Amateur Radio software, nothing specifically ties its use to Amateur Radio. There are alternative radio systems that require no licensing and allow data transmissions between stations. Networks can be deployed using such systems and Xastir; however, you would lose access to the rich set of interconnected networks that exist in the Amateur Radio APRS system.