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Dee:
I don't know about how the laws cover physics in your neck of the woods, but here it goes like this: The "bandwidth" of my phoneline just happens to be about 300 hz to 5000 hz (this can vary widely with equip--but the phone company pretty well guarantees this minimum) and, my computer modem uses this "audio bandwidth" to send/recv data at speeds up to 5.7K bytes per second. Now, I just happen to know a guy with a transceiver which he put mic level jacks on to interface with a transceiver and a USRobotics external 57K modem and set to software flow control and ignore the fact there is NO DC carrier voltage on the line. Since the transceiver he hooked the modem to has a modified audio recv/xmit bandwidth of approx ~100 Hz to ~8K he has PLENTY OF BANDWIDTH. .... now really, a high school student should be able to manage this--indeed, the one I seen did... the USR modem takes care of data compaction and error control--pretty straight forward really... I expect the other hams will "discover" and present this "revolutionary" idea within the next decade. grin .... from there it was a simple matter to take/input the audio from/to the transceiver from the computer sound card and do enhanced encryption/compaction by means of software on the digital signals--basically you find very similar in cutting edge technologies--and while I am not 100% certain--I would almost bet it is done nearly 100% in a similar fashion... being a software engineer, I can almost guarantee that part--I am a little less sure about how they implement the hardware and I rather doubt it is an ancient 56K phone modem ROFLOL!!! Works equally well for data/voice/video. That is all taken care of in software, you simply need to know what type of data you are getting, if you try to interpret voice as text or the opposite--I am sure you can see there would be a problem... I might add, the first time I seen this done was over five years ago... so really, the hams may have it as quickly as another five years! innocent look John "Dee Flint" wrote in message ... "John Smith" wrote in message ... Dee: The only person talking 300 baud is you, I told you to throw away that 300 baud modem and get a decent one (or revamp an old phone modem to your needs.) Since you didn't even understand that, you certainly won't grasp the rest... John Well it just happens to be against the rules to use higher than 300 baud on HF so that is the limit that the data/video/audio signal must fit within. There is a very good reason for that limit. The higher the baud rate, the greater the bandwidth required, and the fewer users can fit on the band. And eventually you hit a baud rate where the required bandwidth is such that one signal won't stay within the upper and lower band edges. Now if you're talking VHF, it's already been done and your "bright, new minds" are a day late and a dollar short. Since you don't understand that, you certainly won't grasp the rest.... Dee D. Flint, N8UZE |
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