QUOTE (ElkGroveDan @ Jul 2 2009, 08:28 AM)

Ham radio! I remember that. It's a way to communicate with people on the other side of the world without the cost of a telephone call. Sounds intriguing.
There's some pretty cool networks HAMs have established:
-- Most cities HAMs have established
repeater networks, so your "handy" UHF/VHF can retransmit your signal at a much highter power.
-- Some repeater stations can allow you to patch into the phone network, which kinda makes it like a cellphone (except since you're also using HAM frequencies, your 'call' must follow the rules of the airways, and of the repeater.
One of the most amazing demonstrations I've seen is commanding a repeater to patch into a VoIP network, which terminates at another repeater, potentially in another country. So your cute, little VHF handy could talk from Pasedena to London. This requires coordination of computers and repeater stations.
Packet radio networks are also pretty interesting.
The tests here in the USA are fairly easy if you know a little electronics. The only thing really to memorize are the HAM frequency bands, with most of the rules being common sense. I think automated transmissions, like the telemetry of a balloon, might get classified as a Beacon signal and require some coordination to ensure nobody else gets trounced at its frequency. Most HAMs are very enthusiastic about electronics projects, so great resource to tap into.
Alas, I earned my license 10 years ago and haven't done much with it.
Cheers,
Tom - KD5MLJ