communication

Really don't know. about the first part of your question

But second bit about modems is easy:-

 basic computing knowledge says:

MODEM = MOdulator/DEModulator

ie A modem converts digital pulses in your computer into radio frequency or telephony system compatible signals......or vice versa (for outgoing and incoming signals)

It provides and modulates a carrier signal for broadcast and then demodulates the received signal (strips out the carrier) leaving the digital information....that can then be processed by software, be it text, pictures or speech data

Whatever MODEM you use your end there has to be a compatible one the other!

For you to use Radio to transmit your data you would need a radio frequency modem and the receiver would need a modem of the same type tuned to receive the broadcast frequency....As with any radio broadcast it would not be private, anyone caple of picking up the signal (and equipped with the same type of modem) could intercept your messages, data etc.unless you employed some very sophisticated encryption software!

Hope this helps?

Well yes, in effect it is. And then it puts the analogue signal over a phone line or radio connection, exactly as Brys described. Whether you are going over a phone line or a radio chanel, you need something to take your 32-bits (or whatever) and serialise them into one stream so they can go over the channel.

If you want to use short-wave for an internet connection, yes I think there are people on uk.rec.sailing who do it. If you ask nicely, you may get a sensible answer out of them. There are some knowledgable people there and also some fairly strange ones.

It's a web Usenet forum. Sorry but since you were asking for one I assumed you'd know how to access them. Via www.dejanews.com is one simple way.

A newsreader is a better one but needs a bit of setup: for example Outlook. From Internet Explorer, Tools -> Mail and News -> Read News. You will need to know the address of your ISP's NNTP server to set it up. Use dejanews if this sounds too complicated.