Wirt Atmar <[log in to unmask]> wrote:

>A few months back, there was a bit of discussion on this list regarding the
>possibility of using the AC electric power distribution network as a LAN (or
>even a WAN). If you remember, we came to the conclusion that it is quite
>possible.
>
>In that regard, the following article appeared today on the business
>newswire:
>
>=====================================
>
>LONDON -- Engineers.................................

>While the technology must still be proven on a large scale, the two companies
>have tested telephone service over power lines in about 20 U.K. households
>over the last 12 months -- with positive results, according to Alistair
>Henderson, chief of technology at Energis PLC, the telecom unit of National
>Grid Group PLC, which owns and operates the electricity-transmission system
>in England and Wales.

.......................................
>While electric lines have been used before to zap tiny amounts of data
>between computers, their capacity has always been limited, making commercial
>applications unfeasible. Now United Utilities' telecom arm, Norweb
>Communications, has found a way to transmit data at a speed of more than 384
>kilobits per second over regular electricity lines -- more than 10 times the
>speed of Internet modems used by most households with regular telephone
>lines.

For me, this article raises more questions than it answers.  384Kb/s sounds
fast, but a standard digital phone channel is 64 Kb/s, making this system
capable of handling all of six phone calls!  There are methods of squeezing
more calls into the space, but the quality deteriorates and 8Kb/s is as low
as you can go.  This amounts to all of 48 phone calls!  I also want to know
how they get this high a data rate across the transformers!

Seems to me, the power LAN has the same kind of problem that the cable
folks do - the lines are shared all the way, unlike a phone line which
heads straight back to the central office without getting mixed up with
anyone else's line.  Cable has the advantage of bandwidth however - you can
fit 600 telephone channels into one TV channel space.  Personally, I'd bet
on the phone companies rather than the cable or utility companies.

John D. Alleyn-Day
Alleyn-Day International
408-286-6421   408-286-6474 (Fax)
[log in to unmask]       http://www.Alleyn-Day.com