w5omr at satx.rr.com
Thu Jul 14 13:17:39 EDT 2005
I got a message from another Ham with a link to BPL article that claims
that BPL is apparently going to happen in the Houston area.
The link for -that- site is
On OUR side of the fence (the radio operators, that is) there is another
argument, and it deserves to be seen by all.
Google is now one of the sponsors of the BPL technology. I am sending a
copy of this message to them, along with
something I sent out a couple of days ago..
Hope you (and them!) can benifit from the enlightenment.
(opposed to BPL)
WHY THE FCC SUPPORTS AMATEUR RADIO
"When a disaster strikes...amateur systems assist with relief operations
immediately. Often, it is from an amateur...that the world first learns
of the disaster."
"Many of our engineers, scientists, astronauts, educators and
technicians took their first steps toward their careers when they became
"The concept of broadcasting began when listeners overheard amateur
stations exchanging weather reports and baseball scores. The first land
mobile systems were built by amateurs. The first hand-held radios were
built by amateurs."
"The first satellite station authorized by the FCC was an amateur
station. Today, more than 30 [amateur] satellites have been launched."
"This [Ham Radio] service is ever at the forefront of communications
Remarks by FCC official during an FCC hearing on Amateur Radio issues, 1990
My personal addition: BPL threatens to take away our ability to
communicate on the very frequencies that could bring life-saving rescue
efforts to emergency stricken areas.
Please, Contact your congress-critter, senator, local/state/national
leaders and let them know that this is a -bad- idea.
Now, the commentary.
By Peter Coffee <mailto:peter_coffee at ziffdavis.com>
The hype around broadband over power lines evades an obvious and grave
risk: radio interference.
Bad things happen when ideal IT concepts bump into the realities of
imperfect hardware. This time, I'm talking about the slow-motion train
wreck of BPL (broadband over power lines), a basically bad idea that's
now the subject of a newly launched IEEE standard process.
With lots of people wanting its benefits and few people understanding
its drawbacks, BPL seems likely to gain too much momentum to be killed.
A win for BPL, though, could be a loss for some valuable applications of
the radio spectrum--but you'd never know that there's a serious risk, or
even a controversy, if all you saw was the IEEE's cheerful July 20
announcement of IEEE P1675, "Standard for Broadband over Power Line
The IEEE announcement calls the BPL proposition "relatively
straightforward," saying "A computer-router combination and a coupler
take the signal from an optical-fiber cable as it enters a substation
and imposes it on the electric current. The signal travels over the
medium-voltage lines, with repeaters placed every 0.5 to 1 mile to keep
the signal viable. A repeater/router near a residence or business
extracts the signal off the medium voltage just before the transformer
and injects it onto the low-voltage wiring on the other side of the
transformer. The signal is now on all of the low-voltage wiring within
the structure and can be accessed at any outlet by plugging in a modem."
The elephant in the living room prompts my follow-up question: "Where
else is that signal accessible--whether it's wanted or not?" Incredibly,
the words "radio" and "interference" are not even mentioned in the IEEE
announcement, even though the risk of radio interference from BPL is
obvious and grave.
BPL proposals place data signals on carrier channels that span a broad
swath of frequencies. Those carrier frequencies overlap those used by
everything from international shortwave broadcasts to standard time
signals to CB radios (remember those?) to baby monitors to the low end
of the range of TV channels. Although not intentionally radiated, those
BPL signals will be traveling on wires that can't help but behave to
some degree as antennas.
We keep signals confined, on a small scale, by precisely tailoring
signal paths in chips and on circuit boards. We control them on a larger
scale by using shielded conductors, or twisted-pair lines that cancel
stray radiation by combining equal and opposite components. And when we
need to convey a complex signal at high power levels--for example, when
feeding a moon-bounce radio antenna array--we don't use just an ordinary
wire. We use a transmission line, a carefully tailored component that
matches voltage and current ratios between the source and destination
and that minimizes stray radiation of signals.
Electrical power lines are designed to carry power and are optimized for
efficiency and safety--not for minimum radiation of high-bandwidth energy.
The IEEE P1675 announcement speaks about traditional power-system
priorities and quotes Terrence Burns, chair of the IEEE BPL Standards
Working Group, as saying, "Power companies face a number of issues ...
for example, how to assess the performance and safety of repeaters/
routers, medium- and low-voltage coupling hardware and other equipment
before buying. Other issues include how best to put this equipment in
place and to keep the overall system operating well and prevent it from
interfering with power delivery. The new standard will help them deal
with these concerns."
Is radio interference someone else's problem?
To be fair, some BPL proposals do include active measures for detecting
and avoiding communication interference. I'm sorry to rain on proposers'
various parades, but shortwave communications are what we turn to when
other things aren't working, and I don't like that failures in a new and
complex system could put an essential backup system at risk.
"Nearly all electrical utilities are exploring BPL because the potential
benefits are so substantial," said Burns. Yes, and there would also be
"potential benefits" in breaking the second law of thermodynamics, but
no one expects to be taken seriously if he or she proposes to try.
Radio's realities deserve equal respect from the proponents of BPL.
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