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Old July 1st 05, 11:57 PM
John Smith
 
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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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