The idea behind allocating frequencies for amateur use is that hams could engage in a hobby with no commercial use which provides an infrastructure for emergency public service communications. To prevent any commercial use of those frequencies, to facilitate enforcement of the rules, and to facilitate the participation by anyone who obtains the proper knowledge and equipment, it is illegal to transmit in a way that "obscures the meaning" of the transmission to people who would want to listen in. So, for example, morse code and ASCII are the only exceptable digital codes, and various modulation techniques are standardized as the technologies are developed.

Actually, data compression doesn't fall under this restriction, because the primary intent is not to obscure the meaning - it is to facilitate more efficient of the spectrum. If you want to apply for an STA (which I hear the FCC is pretty liberal about) you can do pretty much what you want to do. If memory serves, this is how ASCII packet was developed and also spread spectrum. -- Ed Carp, N7EKG ecarp@netcom.com, Ed.Carp@linux.org "What's the sense of trying hard to find your dreams without someone to share it with, tell me, what does it mean?" -- Whitney Houston, "Run To You"