From: "Jim Hampton" on Wed, Aug 17 2005 4:29 pm

wrote in message
Jim Hampton wrote:
wrote in message


Power lines were never meant to carry HF communication signals.

No kidding?!? From whom did you pick up that factoid? :-)

They're lossy at HF because they radiate! The whole concept
is deeply flawed. By allowing BPL systems, FCC is setting
a very bad precedent by saying it's OK to pollute the electro
magnetic spectrum with noise, even if there are viable
alternatives to the noise-producing technology.

A couple of points he First, the FCC does NOT "allow"
Access BPL existance. Access BPL systems are (note
carefully) UNINTENTIONAL Radiators.

Secondly, the FCC has never ever established any "radio
service" about or for any Broadband Over Power Lines
concept. BPL is a WIRED system; i.e., NOT an intentional
radiator of RF.

Thirdly, the FCC DOES CONTROL RADIATED RF LEVELS AND TO
ESTABLISHED SPECIFICATIONS NOW IN TITLE 47 C.F.R. That
radiation level HAS been quantified and put into an Order
that did appear both in the Federal Register and at the
FCC website under the Office of Engineering Technology
link. It wasn't under the Wireless Telecommunications
Bureau page nor the Amateur radio page under that (there
hasn't been any new link on the amateur page there since
2002).

The NOI (Notice Of Inquiry) of the FCC that caused this
recent flap and furor was NOT about the existance of BPL
as any service...IT WAS ABOUT MEASUREMENT METHODS TO
DETERMINE ACCEPTIBLE WAYS TO MEASURE THE RADIATION.

The OET knew damn well that BPL would radiate. But, they
could NOT LEGALLY STOP BPL from existing. All they could
do is establish a legally-acceptible MEANS OF MEASURING
THAT EXPECTED RADIATION.


Well, by limited interference, I am suggesting that BPL be limited as any
other unintentional radiator.

It IS. One has to scrounge around the FCC webiste a bit to
find it, but it IS there.

I do hear your point and it is well taken.
We do *not* need "only" a 10 dB increase in noise in general LOL

Nobody does, but it has happened. Listen to the "ISM" bands
and the DSSS and stuff there does raise the noise floor.
However, the occupancy of those ISM bands is nearly ALL that
mode and those users coexist peacefully.


Also, as we are well aware, no filter is perfect, whether a notch filter or
a bandpass filter or any other filter. Also, filters introduce distortion
into the signal.

Irrelevant. Those "notch filters" can't erase MOST of the
frequencies on HF. The "licensed users" and the UNLICENSED
listeners are spread over most of the HF spectrum.

So, it remains to be seen if the power companies can come
up with a BPL with very limited impact on licensed services. I do have my
doubts, but am only suggesting that *if* they can prove a system can produce
very low noise in the airwaves, then it might be worth a try. That is a
*big* if.

Many, many things ARE possible. The last 109 years of the total
existance of radio have shown that.

However, TRANSMISSION LINES of signals are technology that goes
back BEFORE the "birth" of radio in 1896. Lee de Forrest, the
inventor of the three-element vacuum tube, was studying
transmission lines academically before his "audion" experiments.
As far as our present-day technology knows (and that is
considerable), transmission lines with lots of discontinuities
will radiate; the TEM field won't be nicely contained. Given
that the ordinary 60 Hz power distribution lines are chock full
of discontinuities and changes in conductor size and spacing
(thus a change in characteristic impedance where that step is a
discontinuity), those power transmission lines WILL RADIATE RF.
That is inevitable.

IF and ONLY IF the electric power distribution system was
designed and REBUILT to known transmission line standards at
HF-VHF could such a wired BPL system be tried out for minimum
interference.

was not