"tony sayer" wrote in message
...
It was eventually determined that there were better, more efficient, and
less troublesome technologies available for broadband delivery, and
dropped,
at least here, although I believe that there may still be some places in
Europe where the tests are still happening. Bear in mind also, that the
generating and distribution companies, use this, or a similar high
frequency
technology, in-house to carry telemetry data around their grid
distribution
network.

What over the 475 kV grid?, don't you mean via the fibre optic at the
top running along the "aerial" earth wire?....

--
Tony Sayer


To Glenn. You've virtually answered your own question there about whether
the mains wiring can successfully handle HF as well as RF, although I was
not actually referring to broadband distribution around the house, rather to
its delivery from the ISP, and this technology has, at least for the time
being, been knocked on the head here, because of potential interference
issues.

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;~}

Arfa