December 17th, 2010
Since I got my amateur radio license back in July, I’ve had a lot of fun with it. It’s a great hobby for anyone technically-inclined or anyone socially-inclined, and between those categories that includes a lot of people. I’ve learned quite a bit over the last few months and really enjoyed it all.
I passed my extra class exam back this fall, and thus got my new callsign, KR0L. So long, KD0MJT. I’ve enjoyed some contesting, as well as general conversations on the system. I’ve also done some work with the keyboard-to-keyboard digital modes on HF. Debian includes a very nice program called fldigi for this.
Of late, I have developed an interest in packet radio. Packet radio uses a networking protocol called AX.25 over RF links. AX.25 bears a familial resemblance to TCP/IP, and in fact, you can run TCP/IP over AX.25 and AX.25 over TCP/IP. My learning curve on packet was somewhat steep. It has declined in popularity significantly since the growth of generally-available Internet access, though seems to be once again growing now. So a lot of information about it is 10 years old.
As I was learning about packet, I of course was using my Debian system. The Linux kernel has long had AX.25 support integrated as a first-class networking protocol. You can open AX.25 sockets, monitor AX.25 traffic, etc. from the Linux kernel. You can use soundmodem to make a software-defined packet modem (called a TNC), or you can use kissattach to hook up to a traditional TNC via a serial port and a protocol strongly similar to SLIP (which, for those of you with shorter memories, is a predecessor to PPP). Linux can do what you’d expect out of a modern networking system: multiplexing with AX.25, handling lots of simultaneous users, etc.
So I was a bit surprised and baffled to keep running into systems that only supported 1 user at a time, couldn’t easily do some things I was taking for granted, etc. Until I realized that Linux is the only major operating system with integrated AX.25 support in the kernel. Things started to make a bit more sense. I hadn’t realized just how awesome a setup I had until I started learning about the hoops some other people went through. It is pretty easy to run a basic client on Windows, but to run the “server” side of things as I am doing — well some of the features just aren’t there or are really kludgy.
Anyhow, I have decided to start documenting things I learn as I go. Beyond amateur radio, I also have sometimes wanted places to stick bits of information. Things that other people might benefit from if they Google, but that maybe aren’t the best blog fodder or website material. So I have set up a wiki, openly editable of course, at http://wiki.complete.org/. To date, only the amateur radio section has much content in it.
I’m also sending in patches and bug reports to the various projects involved in amateur radio in Linux, and am glad to see development has resumed on several of those.