Imagine turning on your radio, and instead of hearing music or your sports program, you hear a buzzing noise that is more annoying than static. You try to tune in your favorite station, but you cannot hear it anymore until you drive out of town, or perhaps you need to turn your radio different directions in order to minimize the noise.

So you turn on your television. Your cable system might have little distortions in it, the traditional TV signal may too.

What's going on? Electro-Magnetic interference generated by Broadband over Powerline (BPL).

BPL is a communication nightmare that the Bush administration seems to be pushing through the FCC. It is the technology that can supply medium or high-speed internet to electrical customers using the power lines for distribution. And due to the design of today's power grid, if implemented on a wide scale, common radio services are at risk for significant interferance radiated by these BPL systems.

Before we get into the politics of the system, let's talk physics. How does the electrical system work? (I will taylor this to the United States) Electricity is generated by spinning magnets around each other at high speeds (3600 RPMs or higher, divisible by 60 -- this is the AC cycle, or Hz (hertz)). This energy is sent through some transformers that step the voltage up at the expense of amperage, and distributed over long un-insulated, non-shielded wires to substations, where the energy is transformed to reduce the voltage and increase the amperage before travelling along more un-insulated, non-shielded wires to local power poles (or underground) to your home.

Electricity travels along the outside of the wires -- not down the middle of them. Electrons move along the outer edge of the cable along the cable, and this electrical motion creates magnetic fields that are perpendicular to the cable. The wires are non-insulated, meaning if you or a tree contact the cables, you will create a short, and get zapped. They are also non-shielded, meaning the magnetic and radio fields generated will escape the wires, and travel out into the atmosphere.

Enter BPL technology. This technology uses frequencies in what we call the MF (middle frequency) and HF (high frequency) spectrum ranging from 1 MHz through 80 MHz to carry data along the wire with the electricity. Because the wires are unshielded, this data will be released to the atmosphere, interfering with other stations that are licensed to be there and transmit.

Your AM radio stations are .520 MHz (520 KHz) to 1.6 MHz (1600 KHz). Shortwave Radio systems are anywhere from 5 MHz to 25 MHz, with some religious programming, marine ship-to-shore communications in between. Television channels 2 - 6 are around 54 - 80 MHz, along with some cordless phones, ham radio frequencies, some police groups, and airplane navigational systems. CB communications take place in the 26.9 - 27.4 MHz range.

It is important to note that frequences below 30 Mhz BOUNCE back to the Earth from the Ionosphere. This physical fact allows us to hear stations from the other side of the oceans, or from stations several hundreds of miles away. If you wanted to talk to someone on the moon, and it was directly overhead, you would need to use frequencies above 150 MHz or so to puncture the Ionosphere and have the signal reach the moon.

This physical fact of bouncing signals below 30 MHz means that a BPL line in California can interfere with a conversation in Texas. A BPL line in Wisconsin could interfere with someone in Florida. The interference is regional, not just localized!

Imagine these frequencies getting interfered with due to BPL, as the unshielded powerlines detailed above will be giant antennas that your favorite radio stations will not be able to compete with.

As I write this, Hurricane Katrina is pounding Lousiana and Mississippi. Major powerlines are down, communications are out, and people are using radios all over the place to communicate, and provide disaster relief. The National Hurricane Center is coordinating efforts on 14.325 MHz, with support people all over the US who are working other radio systems that are local to the hurricane's path. Imagine this communication being impossible due to BPL.

Sure, BPL suppliers will claim that they can surpress (they call it notching) certain frequencies so that there won't be any interference. But this is a "steal from Paul to pay Peter" approach. Customers who purchased BPL will want their services, so if the supplier notches out 14.352 MHz, someone at 14.725 MHz might have to suffer. And the FCC has not made it easy for people to prove that they are interfered with, nor has the FCC provided immediate relief for that interference. And since BPL interference bounces around in the atmosphere, a person in Georgia might need to talk to New Mexico to shut the interference off!

BPL affects airplane navigational services. It interferes with shortwave radio signals. It will get into your house and cause problems with your electronic devices -- how many of them will have circuitry to remove the BPL pulses from the powersources? Everything you plug in could have the "noise" of the BPL signals... everything from the VCR to your hair dryer. These devices were not built with BPL interference in mind.

BPL is radiological pollution that we do not need. There are much more reliable methods of distributing the internet -- cable, fiberoptic, satellite, and telephone line. The BPL people are selling the idea of wiring the home in the fields, but they cannot recover the investment costs due to the low population density in the rural areas. Communication is the lifeblood of today's society. It is how we get things done, and we do not need to generate an electro-magnetic fog of static and noise for a few people to get onto the internet.


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Personally I'd be surprised if the FCC would permit something that would cause such widespread interference. I know they do stupid things, but I've always figured they at least kept interference to a minimum. But then, I'm not really an expert.

That said I don't see the point of BPL. Cable and telephone lines cover most everywhere, and where they don't the goverment could subsidize their deployment. We are falling way behind in broadband deployment compared with the rest of the world (south korea for example), but this is mostly because the population centers in the US are so spread out.

Just out of curiousity (as I really don't know anything about this sort of thing), why is it that the powerlines are uninsulated? Would it really be that much more expensive? Would it degrade the signal signal somehow? Add resistence? Enquiring minds want to know.

"As I write this, Hurricane Katrina is pounding Lousiana and Mississippi. Major powerlines are down, communications are out, and people are using radios all over the place to communicate, and provide disaster relief. The National Hurricane Center is coordinating efforts on 14.325 MHz, with support people all over the US who are working other radio systems that are local to the hurricane's path. Imagine this communication being impossible due to BPL."

Fearfactor USA... First you say the powerlines are out (and thus not interfering with radio...), then you go on and say those same powerlines are making radio comms impossible.
Make up your mind.

Your fears of long range interference are unfounded. The power in the signal would be so low it will not interfere.
The main reason some people are against it is precisely the lack of reliable information you're portraying leading to the scare scenarios you're writing about.
These myths are perpetuated by people with a set interest in preventing the technology from being implemented who are mainly people with a large stake in existing communications networks (cable, telephone).
They stand to loose their stranglehold on internet access, or at least see it weakened a lot.

And even if there would be interference, the long distance lines would not carry the signal at all.
The losses on these lines are far too high for that (line losses of electrical power are so high that anything over a few hundred miles is uneconomical, and that's without having to worry about loosing signal strength) unless they're being given massive amounts of shielding (which makes them unprofitable).
The short distance lines are mainly underground by now, with the ground providing shielding against any interference that migh develop.

"Just out of curiousity (as I really don't know anything about this sort of thing), why is it that the powerlines are uninsulated? Would it really be that much more expensive? Would it degrade the signal signal somehow? Add resistence? Enquiring minds want to know."

Weight mostly. If insulation were added to overground lines to prevent or seriously reduce line losses the cables would get so much heavier the distance between the towers would have to be halved or worse.
That would make the whole system not just a lot more expensive to build and maintain (even without taking the higher cost of the cable and transport of it into account) but impossible to implement in many areas where the land is built up. You might even have problems crossing wider rivers unless you could build towers in the middle of the river bed (which while technically feasible would interfere with shipping and be extremely expensive).
Underground cables (which don't have these restrictions) often are shielded at least partially (as part of corrosion protection layers etc.).
But here too cost is a factor in deciding how far they can go in adding shielding, as at some point the cost of adding more would be higher than the prevented line losses over the expected life of the cable.

Mr. Wenting,

There is no fear concerning the situation. Where BPL was tested in the United States, there are documented cases of interference rising through the roof. A number of the test sites were shut off after measured increase of interference. We call this the "noise floor".

Also remember that this is not a local situation -- the radiations are below 30 MHz which propogate throught the atmosphere, and bounce off the ionosphere mean that if the power goes out in one particular area, interference can still be received that was generated in another area.

Amateur Radio can contact and communicate point to point for hundreds of miles due to propogation rules. Amateur radio transmissions are only several kilohertz wide, meaning they are tuned, and not a large spectrum killing signal. BPL is such a large spectrum killing signal.

Perhaps you would like to read the NTIA report -- National Telecommunications and Information Administration. In that report, it talks about interference to airplanes, shortwave radio, and mobile users. It is highly technical.

Powerlines are not insulated due to weight and cost. And they were designed to carry alternating current @ 60 Hz, and nothing more. They were not designed, nor constructed, to carry information on them. There is nothing preventing a transmitter from zapping out BPL either... as the strongest emission "wins". A radio station could prevent BPL from working properly.


My employer- which is NOT an ISP but is instead in the oil & gas business- is opposed to (most) BPL technology. We've monitored the ongoing deployment of BPL with great discomfort.

For the safety of the public and the environment, it is essential that we maintain around-the-clock communications and control with our production facilities (this is particularly true for operational facilities in the Gulf of Mexico and for pipelines). Therefore we install multiple levels of communications redundancy, and the systems of last resort utilize VHF and HF frequencies. For the technical reasons already stated, my company remains concerned that some popular BPL technologies have the potential to interfere with emergency communications, even when such BPL systems are located distant from one or both ends of a link.

To my knowledge, there are only two BPL manufacturers who propose technologies that virtually eliminate the interference potential. These make use of microwave frequencies rather than HF or VHF frequencies. Due to the particular characteristics of propagation at the proposed frequencies & power levels, their technologies should pose little or no risk to existing radio communications systems. Unfortunately, it appears that few (if any) of these "acceptable" BPL systems have been deployed.

Now, regarding the FCC's role . . . literally thousands of comments were filed in opposition to BPL as described within the FCC's NPRM (Notice of Proposed Rule Making). Most were from individuals (primarily licensed radio amateurs) but many were from commercial/ industrial & government entities who operate licensed radio systems on HF and VHF frequencies. As noted, the most telling comment filed in opposition was submitted by the NTIA. When the dust cleared, most of these parties must have wondered why they went to such effort to educate the FCC on basic radio theory: the FCC wasn't about to let a few bothersome facts stand in the way of a perfectly good fantasy.

IMHO, the FCC disregarded sound technical arguments from expert sources and apparently facilitated BPL deployment for purely political and economic reasons. As a telecommunications engineer, I believe that other broadband technologies, particularly wireless (WiFi & WiMax), are not only more practical (& economical) than BPL but do not inherently risk interference to licensed radio systems. It's also my opinion that by their de facto approval of certain unacceptable approaches to BPL technology, the FCC failed to act appropriately to protect licensed users of our radio spectrum in particular (and the national resource in general).

As things stand now, I must agree that BPL is a very bad idea. Thankfully, it is not yet widespread. Perhaps it will fail when placed against the competition (cable, DSL, wireless, etc.) or perhaps future BPL systems will completely avoid the HF & VHF portions of the radio spectrum. Either would be fine by me.

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