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To: Jim Posey who wrote (1327)7/30/1998 8:25:00 PM
From: nommedeguerre  Read Replies (2) | Respond to of 7618
 
Jim,

>>"I can see how the basic premises of Shannon's limits might be bypassed to achieve better than commonly accepted performance."

Funny, this is an opinion not a proof. Other PhD's have a different opinion backed up with evidence and mathematical proofs. So far the skeptics are still ahead in the game.

>>By the way, I have all that I can handle here at home. How come you have to go all the way to Norway? Couldn't think of anything better to do with Inga than skiing?

You live with your ho? Or do you just find that you have lots of time alone with your stepdaughter? I like your retorts; makes one nostalgic for high school. I'll bet you are a riot when you start working on the second half of your twelve-pack.

Cheers,

Norm



To: Jim Posey who wrote (1327)7/30/1998 9:49:00 PM
From: paulmcg0  Read Replies (1) | Respond to of 7618
 
It's not just a matter of the Shannon-Hartley limit, although that's a big one. You will also run into real world constraints (which you have to take seriously, as an engineer, instead of a theoretician) with the existing telephone infrastructure, the so-called "plain old telephone system". Because of how the DS-0 line cards work down at your telco central office and their use of the Nyquist sampling criteria, the most you can get out of an --unmodified-- analog line that gets converted into a digital signal at the phone company is 64000 bits per second (64 Kbps). Because of things like bit stealing, and an actual audio bandwidth closer to 3.7 KHz instead of 4 KHz, realistically, the best you can hope for is 56 Kbps, which has been accomplished. The next step is to change the existing equipment at the customer end, and at the central office end, to use xDSL, and then, you can modulate a broadband, high speed carrier on the existing copper wiring. You should consult technical documents that the telephone industry uses, such as Bellcore SR-TSV-002275, "BOC Notes on the LEC Networks", 1994, which goes into hundreds of pages of technical detail about how the phone system actually works between the central office and the customer, and all the limitations. This stuff is a lot more complex than the "How Sparky makes the telephone ring" comic book that your understanding of the telephone system is based on.