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.
Christian
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