In my teens I spent many enjoyable hours tinkering with radio equipment and communicating with other “hams” around the world through the medium of amateur radio. Moving away to attend a university and start a career and family meant that my hobby had to go on temporary hiatus for a number of years. Recently, I came back to the hobby and decided to explore an area of amateur radio that didn't exist in my teen years—digital packet radio. As an avid Linuxer, I was intrigued to see how I could use my Linux system for packet radio. I was on a limited budget, and wanted to get started without investing in a lot of hardware and software.

Amateur radio is a pursuit enjoyed by millions of “hams” around the world. By international agreement, most countries have allocated a portion of the radio spectrum for amateurs to experiment with radio technology. The hobby goes back to the early days of radio and is popular with people of all ages. Operating an amateur radio station requires an operator's license, which can be obtained by passing an examination that covers radio theory, regulations, operating practices and basic electronics. Full privileges also require a knowledge of the International Morse Code (yes, it is still used) although some countries now offer no-code licenses that typically include restrictions in operating modes and frequencies.

Hams are known for building their own equipment and accessories, experimenting with new technologies and helping each other and the public. This is close to the spirit of Linux, so it is not surprising that many hams are also Linux users.

As personal computers became increasingly powerful and affordable, amateurs looked at using radio for digital communications. Packet radio is one such method in which text is encoded as binary data and transmitted via radio in groups of data, called <span