Len Over 21 wrote:
Mike, the "X10" system works at only a few hundred Hz of spectrum.
I'm not familiar with the specific names. X10 is the one the power
companies use?
There was another system that was used to control clocks in schools and
other places where the clocks need to show the same time over
At no time was any part of the US electrical distribution system, home
to generating plant, EVER CHARACTERIZED OR STANDARDIZED
AS R.F. TRANSMISSION LINES OVER A 1 TO 80 MHz FREQUENCY
RANGE!
Apparently the Office of Engineering and Technology at the FCC doesn't
understand that yet...?
I can look out at my neighborhood's electrical distribution system and
see "RF transmission lines" that must vary from several hundred Ohms
to just a few Ohms within the metal conduit of my home.
That is NOT any sort of "RF transmission medium" that anyone can
expect to work at either smooth, easy, or trouble-free radio frequency
transmission. There's discontinuities up the ying-yang there and
wherever there are discontinuities, there is also the danger of even
more radiation (in addition to introducing more attenuation).
So if this was (is) such a good way to send signals, why wasn't the
internet developed this way in the first place?
For the simple reason that it does NOT work very well. :-)
I guess I was kind of knowing the answer as I asked the question. 8^)
It's intellectual dishonesty for those companies to try to sell it as
something that will work.
But even if it is a failure, some will be able to make money on it..
for while.
I've got a pair of Phonex through-the-line coupled "modems" that are
supposed to work between two rooms here. It's the second pair over the
counter, the first pair returned because they don't work well. Second
pair is no better.
One good reason why they don't work is that the AC wiring in one room
is on one side of the "double-phase" split from the pole drop and the
outliet
in the other room is on the other side. Neither Phonex or any other of the
Homeplug group explains that.
I can hear it now.........."We need to rewire your house to get your
BPL modem to work!" 8^)
I measured an attenuation from the AC outlets better than 30 db from
10 to 80 MHz, 36 db being lower limit of this setup. The attenuation is
probably greater than that. No sense in improving the test setup with
that much attenuation...it is already too great.
Interesting. As a comparison to my cable modem hookup, There was a lot
of adjusting of the line levels to get a good signal to my home office.
If the installation included boosting the power enough to overcome that,
there would be some serious RFI running around.
I believe that I am skeptical enough that even if I didn't have a
technical background, that question would pop up pretty quickly when
considering BPL.
Carl, is there any other way that we can aid this fight?
One of the first things to try is to force an explanation of how all the
vaporware BPL systems work. NONE of them explain it in enough
detail to make any electronic sense right now. They haven't done so
in any of the prominent electronic trade publications yet...other than
more generalized, non-specific-detail claims. Vaporware.
Agreed!
- Mike KB3EIA -
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