"D Peter Maus" wrote in message
...



BPL has not been of checkered success in other countries. But FCC has
made a commitment to it. Short of a sudden burst of good sense, they're
not likely to back down, especially with the enormous commercial money
being poured into it.

..
BPL has mostly flopped in real world tests in the US, as well. However, I
don't think the FCC has actually made any commitment to BPL. By allowing
BPL, they've put themselves in a win-win position. If it works, millions of
voters get a broadband internet access choice they otherwise wouldn't have.
If BPL falls flat, no politician gets to point his finger at the FCC and
claim "The DSL, cable and satellite interests are running the FCC!!"

The second scenerio would be particularly attractive if the folks at the FCC
were convinced that BPL doesn't really work.



My question is: How does BPL perform with electrical noise on the
same line. The further out a line runs from the hub, the more noise it
can pick up from switching, appliances, other electronic devices. We're
all familiar with the huge noise output of an SCR dimmer. That's because
of the enormous switching generated by the On/Off switching of the SCR.
Since BPL is targeting rural users, where Edison can run on very long
lines which are more susceptible to picking up, and radiating noise from
high current transients, transients of surprisingly rich harmonic
content, how's this going to affect digital devices taking down data
bursts which may contain harmonics from these switching transients? Even
modems are affected by low level noise on the line, which can create
errors, and eventually disconnections. AC lines can be dramatically
more noisy.

Absolutely. And you don't need imagine anything as high tech as a light
dimmer or a switchmode power supply. How about a sparky 'ol vacuum cleaner?
How would BPL perform in a thunderstorm?

And that isn't even considering all the changes in RF reflections as
circuits get switched. Lights go on and off. The neighbor's washing
machine cycles. And the bigger the digital party line, the bigger the
potential problems.


I don't hold out a great deal of hope for the commercial success of
BPL, but I don't suspect anyone in a position to change things will
admit that until the damage HF usage has been compromised.



I don't think the worst case scenerio, thousands of miles of HV power
distribution wires carrying high speed digital signals, was ever practical.
There's interference, there's unpredictable reflections and, even in the
most optimistic case, the available bandwidth won't split among alot of
users and still be high speed.

There are other approaches which promise to cause much less interference,
although I think the real motovation is to minimize BPL's vunerabilities:

http://www.arrl.org/news/stories/2005/05/23/1/

Frank Dresser