BPL, what is it and why am I
hearing so much stuff about it? This Web page is dedicated to proving
information about the threat of BPL, or Broadband over Power Line, and the
threats that it poses to communications in the range of 2 to 80 MHz. We will
explain how it works and why it will be a source of interference as well as
explaining why existing services will likely interfere with it.
BPL is yet another method by
which Internet service providers and other services can be delivered to homes
and businesses. The promise is to provide alternative, low-cost, reliable
service to consumers. The concept is to use the electric utilities’ existing
power distribution grid as a massive data network. This is really nothing new,
in fact, the power companies have been doing this for years. But with far
different results.
Up until now, the power
utilities use their grid to carry data signals in the VLF spectrum, around 176
KHz. At these low frequencies, there is little or no problem with the
transmission. So, why is it a problem with BPL
The power distribution grid
consists of miles and miles of parallel conductors. Not unlike TV twin lead or
good old ladder-line, this distribution grid is a series of transmission lines.
The difference between the power grid and the feedlines that we are familiar
with is the line spacing. And herein lies the problem. At 60 Hz, the normal
power frequency in the United States, and even at 176 KHz, the spacing of the
conductors is such that it is a small percentage of the wavelength of these
frequencies. As a result, there is little “incidental emission” of RF.
Incidental emission is a term the FCC uses when regulating the operation of Part
15 devices. The power grid falls into this category.
Part 15 is meant to protect
licensed services (like the Amateur Radio Service) from incidental radiators.
Household appliances, such as televisions, computers and cordless telephones
all fall into the Part 15 realm. But, so does the power company’s distribution
grid. They are held to strict limits of incidental radiation of RF, so as not
to interfere with other services.
We are all familiar with “power
line noise.” This is intense static produced when the insulators on the power
lines becomes damaged or dirty and allow the high voltage electricity to arc
over. This produces wideband noise that will affect communications from the VLF
region clear into the VHF spectrum. It is also a source of revenues loss for
the power companies in that it represents wasted energy, energy that could be
sold to a consumer. For this reason, power utilities are generally cooperative
in dealing with trouble spots on the grid, usually identified by an amateur
radio operator in the neighborhood.
So, the power grid is good at
not radiating the low frequencies such as 60 Hz or 176 KHz. But, what happens
as the frequency increases? As you should know, as the frequency increases, the
wavelength decrease. At some point, the spacing of conductors in a transmission
line will be a large percentage of the wavelength of the signal transmitted and
the transmission line will begin to radiate more signal. If you use ladder line
or other parallel feeders, you know that they function quite well in the HF
spectrum. In fact they are usable into the UHF region for certain
applications. But the line that we use for our radios is typically a few inches
wide at the greatest. What happens if we were to use ladder line in which the
spacing was 10 feet or more?
The answer is that the
transmission line would no longer be a transmission line. Instead, it would now
be a radiator. And if it were the power grid, imagine the radiator that it
would be! Miles and miles of cable in the air! Every amateur’s dream! But,
since the power utilities are now trying to send HF radio signals down their
transmission lines, well, you can imagine the results. The power grid is not
designed to transmit these signals.
So, what do these signals look
like or sound like? At present there are demonstration systems undergoing
testing here in the United States. The American Radio Relay has done extensive
testing with mobile HF equipment, driving through the test areas and observing
the results. What they find is that when the system is operational, the entire
HF spectrum is blanketed by wide band noise. Not the familiar “line noise”
crackling and buzzing but a severe, pop-corn-like sound, that obscures any
signals below the level of the noise. And that noise level can be above S-9.
If an amateur radio operator or any other HF radio user (short wave, Citizens
Band, military or government) were in the vicinity, his radio may become useless
for communications
.
So, why is all of this
happening? Why isn’t something being done to stop it? This is happening
because the power utilities are seeking another source of revenue from their
infrastructure. The FCC has mandated that broadband services will be made
available to every household in the country. So, the power companies see this
as a easy way to get into the marketplace and provide an alternative means of
access for rural areas and areas not served by other high-speed services such as
DSL. The power grid goes virtually everywhere. So, the reasoning is that so
can broadband access. And, the FCC is strongly supporting the development of
this technology. The FCC is encouraging the power utilities and hardware
vendors to push forward in developing BPL technology. But there seems to be
little concern about the consequences. There is much being done to fight BPL.
And more is being done every day. More on this later.
We can understand how BPL can
interfere with other services, but we stated earlier that those same services
can potentially interfere with BPL. How is this so. Well, antennas (and
transmissions lines) have what are called “reciprocal properties.” That is to
say that an antenna that radiates well, will likely receive well, too. So, the
power grid, being a good radiator at HF, will also excel at picking up local
radio signals. Signals, say, from AM and shortwave broadcasting stations,
amateur radio stations, and other sites. And while these stations may be
operating legally, they can still be a source of interference with the BPL
systems
One of the beauties of Part 15 is that if an unlicensed service receives
interference from or interferes with a licensed service, it becomes incumbent on
the Part 15 service to resolve the problem. However, can you imagine
an amateur radio operator trying to explain to his neighbors that he is not at
fault with the interference they are receiving, that it is up to the
manufacturer to fix the problem? Imagine, if you will, how this will play
out across the country. Thousands of consumers, having their Internet
connection “shutdown” by that “guy with the big, ugly antenna down the street.”
Not a pretty picture. And the guy with the antenna was just operating
within his granted privileges. Privileges that are supposed to be
protected from Part 15 interference.
BPL has been tried in other
countries. It was tested in Europe and in Japan, and in both situations, was
justifiably shut down. Cost and interference issues were cited as the reasons.
Cost? In order to use BPL, the power grid will require upgrades. These
upgrades are costly. They require “repeaters” every few thousand feet because
the power grid is not an efficient transmission system for these frequencies.
(Surprised? Shouldn’t be. The fact that it radiates so well, means that not
all of the signal is making it to the destination. Most of it is lost in
radiation. No surprise, really.) Then there is a matter of all of the
transformers and other devices in the grid. Transformers are low frequency
devices and not very efficient at passing higher-frequency RF. They are very
good at passing 60 Hz and 176 KHz, though. So, all of that hardware must be
bypassed by another piece of hardware that allows the transmission of the BPL
signals. And this all costs money.
In spite of all of these
negatives, though, BPL advocates are still trying. There are new test programs
cropping up in Europe, and now here in the United States. The scary thing is
that under current Part 15 rules, they are totally within their bounds to do
this, without the FCC making any changes to the rules! But, because of the
technical reasons given above, the BPL industry is lobbying the FCC to revise
the Part 15 rules. They want to be able to run higher power levels (to overcome
the losses in the system, of course). This means even more incidental
emissions.
To deal with this whole issue
of BPL, the FCC, early in 2003, issued a Notice of Inquiry, or NOI, that asks
what can be done to mitigate the Part 15 limitations and how Part 15 could be
changed to allow for the rapid development of BPL technology. “Changes to allow
development of BPL technology?” You got to be kidding, right? Nope. No joke.
This is what the FCC asked for. And they got what they deserved. A mountain of
responses to the NOI. Over 2500 of them, the majority from radio amateurs.
There were responses from the BPL industry, and other HF spectrum users. Clear
lines have been drawn between the two factions. The BPL advocates say that
there is no problem, that there won’t be any interference. While at the same
time, the ARRL has produced evidence that there is, in fact, huge amounts of
interference. The BPL advocates then counter, stating that if there is
interference, then the incumbents will have to move to other frequencies. So,
one must ask, if a system doesn’t produce any interference, then why even
suggest that the incumbent users move? But where would they move to? There is
no other part of the spectrum that exhibits the properties of the HF portion.
The HF portion of the spectrum is essential for long-distance communications.
There are no other frequencies to move to , should BPL be allowed to
proliferate.
And proliferate it will, unless
we do something about it. The ARRL and other organizations are mounting
campaigns against BPL. It will be a huge effort. The power companies represent
a formidable opponent, and they have the support of the FCC. But, what is
needed is to make the case against it and convince the Commissioners that BPL is
not a good idea and it should not be allowed to continue. Further testing and
research is required. Demonstrable test results speak loader than arm waving
and making noise. It is important to make all HF radio users aware of the
problem posed by development of BPL.
You are encouraged to help out.
You can write to the people and organizations listed below. Ask if they are
aware of the potential problems that can be encountered if BPL should be allowed
to be deployed. Ask what they are doing to combat it. Voice your concerns.
Explain that you are a spectrum user and are worried about how it might affect
your operations. As an amateur radio operator, how would it impede your
abilities to react in times of emergency.
You can write to the power
utilities and tell them that you think it’s a bad idea as well. As a consumer,
you don’t need yet another alternate high-speed service access to the Internet.
And when BPL is a dismal failure, you don’t want to be burdened with the costs
incurred by the utilities foisting a dead-end technology on us. Write to the
share holders of the manufacturers asking why their company is spending millions
of dollars on a technology that will ultimately fail. And fail it will, the
laws of physics will not change through the acts of lawyers and regulators, and
no amount of regulation will change that.
BPL Advocates' Comments Lack Technical
Substance, ARRL Reply Comments Say (Aug 21, 2003) -- The ARRL
says Broadband over Power Line (BPL) proponents failed in their comments to
the FCC to substantiate their claims that the technology will not cause
widespread interference. In reply comments filed August 20--the FCC's
deadline to receive comments in the proceeding, ET Docket 03-104--the League
said that if the FCC is going to rely on industry statements in making
decisions on BPL deployment, the industry should back up its assertions with
technical studies and hard data and make these public.
