In article , Arfa Daily
wrote:


To Tony. You're right. In recent years, the electricity companies have
installed fibre optic links, but I'm fairly sure that when they first
started using this method of communicating amongst themselves, they did
make use of the full distribution network, including the supergrid, but
I may be wrong on that. How much power volts are on the line, shouldn't
make any difference. It's still just a piece of wire, with HF skin
effect, to the comms signal. I believe that with the PLT internet
trials, the injection points were at central substations, so I guess
that this must have been working at up to at least the local 11kV
distribution level. Just as an aside, I think that the grid and
supergrid operate at 275kV and 400kV, not 475kV. I also have a dim
recollection of reading somewhere, that the 25kV overhead lines on the
uk rail nework, were also used for HF telemetry, but again, I could be
going off on one there. Suffering from CRAFTs disease, don'tcha know
... !! d;~}

FWIW Barry Fox had an article in the current HFN. There are still companies
trying to use EM signals (not wrapped optical fiber) to send data along the
mains to houses. He was trying to warn audio makers, fans, etc, to object
to this as it might cause some problems. The reason being as others have
indicated - that it is inherently a poor route for such signals, so they
will need to 'shout' to get it to work, thus causing problems to people who
don't want it. However I suspect this will be more of a problem for radio
than for things like amplifiers or CD players *if* it actually succeeds and
is at a high enough level to be a pest.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html