Bartman said:
*Sigh* What a annoying debate. *IF* power line does produce 'gross pollution', please explain exactly what that is, in laymans terms, im not wading through tons of tech stuff.
And what are the bad effects of this pollution if it will exist?
People can find good and bad evidence on the net till the end of time (or until powerline rolls out or not), but I see no real reson for it not to go ahead. All this mention of pollution, and not a lot about what it will actually cause. Unless I missed it skimming through the techy stuff.
Sorry the debate has gotten technical, but when others try to play technical and the core problem with BPL is its technical foundation, it's hard to avoid it. I won't argue the business model of BPL as it's not my field of expertise. Others on this board are venturing into areas where they lack knowledge. I also won't dispute the dire need for broadband.
So I'll try to provide a layman's view of this, and will smack myself if I start throwing in acronyms
Power lines were designed to carry very low frequency energy and deliver power, not data. The power is carried very well and if lines are properly maintained, they deliver most of the energy to the destination. Some is emitted into the air, but this amount is neglible compared to the amount of power delivered.
The data carried in BPL is much, much higher in frequency. In simple terms, this higher frequency would prefer to "jump off" the line and propagate through the air rather than stay on the line. This causes the data signal to be lost and have to be regenerated periodically on the line to make it stronger.
This "emitting" of the data signal in and of itself is not harmful. The problem is the frequencies that BPL uses and emits. The emissions will affect a band called HF which extends from 1 to about 30 Mhz, and the lower part of VHF 30 Mhz up to around 80 Mhz.
Internationally there are licensed occupants of this band using it for long distance worldwide communications. This varies from country to country, but basically it consists of military, government, maritime, aviation, shortwave broadcast, and amateur radio stations.
The HF band exhibits some properties unlike any other radio spectrum. The distance you can communicate varies significantly with geomagnetic and solar conditions. Also, the amount of power required to communicate varies. With the right conditions you can use a miniscule amount of power such as 1 watt (1/100th the power of your typical lightbulb) to communicate around the world.
The effectiveness of the power lines in radiating interfering signals in a band that has a properties like HF means that even low signal levels emitted could disrupt communications. Some BPL signals are very wide, meaning they blanket large portions of spectrum with crackles, pops, or continual whining noises. The current occupants of the HF band need "quietness" as they often receive weak signals.
Current occupants of the HF band cannot be relocated due to the cost, international treaties, and the specific properties of it that are required by the services there.
There's also the potential that "bad spots" that inevitably occur in power lines due to weather and poor maintenance will create radio "mixing" products. This is a phenomenom were radio signals "mix" together to produce new radio signals. The result is the signal which was originally just in the HF band is now extending into high frequencies and would affect public safety and local aviation frequencies, to name a few.
Again, this is a very simplified explanation and I've taken some liberties in giving radio signals human traits, but I hope this enables you to understand the technical issues better.