An Amateur Radio Survival Guide for Linux Users

APRS (Automatic Packet Reporting System): location-aware services are starting to emerge as our mobile telephones gain the hardware, connectivity and software required to support them. As with many things, Amateur Radio operators are ahead of the curve here as well. For more than two decades, operators have been pairing radios and modems with GPS receivers to transmit their positions to others. Initially used for local-area positional awareness during public events, the system now is interfaced to the Internet, providing a way to track people from a Web browser using Google Maps. APRS is easy and inexpensive to use, and it provides features and functionality above even some so-called modern services. On a recent trip, I was more than 100 miles away from cellular coverage, but my friends were able to track my position through the APRS system.

Satellite communications: did you know that Amateur Radio operators have satellites in space for the sole purpose of facilitating communications? With an inexpensive radio and some creative antenna work, you can communicate with an amateur satellite for the purposes of digital exchange or even analog voice calls. Linux users are not excluded from this activity. If your distribution provides the gpredict package, take a moment to install and run it. You might be surprised to see an amateur satellite passing overhead as you read this (Figure 2).

SDR (Software Defined Radio): historically, radios have been complex purpose-built analog devices that depend on a lot of filters, resonant circuits and other components. Increasing performance of these devices often means adding additional filter stages and, recently, embedding Digital Signal Processors (DSPs) to cut noise and block unwanted interference. A new generation of radio technology recently has emerged that uses very simple, wideband, general-purpose radio components and relies on the high performance of a modern PC to do all the hard work. The result is what is called a Software Defined Radio or SDR. These systems have incredible sensitivity and are extremely flexible. Several projects exist that are working to push the envelope of this new technology, but the most interesting to Linux users probably is the GNU Radio Project (see Resources).