The BPL Myth

**Pexster** · March 4th, 2004, 11:26 AM

Every day lately, I see another news article about how great BPL (Broadband over Power Lines) will be. NONE of them have mentioned the obvious problem -- massive amounts of RFI. Maybe this from the ARRL will get published. I certainly hope so. I fear that if this goes forward unchecked, I might as well throw out my radio.

What's irritating is that the FCC knows this is a problem, yet they just pretend it doesn't exist. Somebody's pockets must have been lined with $$$.

**Solid Snake** · March 5th, 2004, 03:07 AM

I think anyone would be lucky to get 56K over power lines, much less broadband. We can hardly push 56K over existing phone lines, lines dedicated for signal use.

**whitebeard21** · March 5th, 2004, 03:21 AM

I read where it is already being used in either KY or WVA and it is free. Sort of a test. I don't know how they handle phase splits going through xfmrs. I know in a home scene that being on diff. legs can cause a problem and the way to check it is to turn on a 220v appliance. If it works you are on different legs and have to change something.

**Solid Snake** · March 5th, 2004, 03:25 AM

They probably use some kind of modulator right on the line, I can't see any kind of serial bitstream surviving phase shifts.

**ClubMed** · March 5th, 2004, 07:59 AM

Im not sure about hardware differences between Here (Vienna) and the US of A, but it's already being tested in Graz and seems to be working fine?

**Pexster** · March 5th, 2004, 08:46 AM

I'm sure it does "work fine" if you ignore that it radiates broad spectrum radio frequency interference at levels high enough to disrupt other communications. FEMA has expressed their concern about this, but the FCC just plowed ahead. The laws of physics apply here. Throw a radio frequency signal over an unshielded length of wire (otherwise known as an antenna) and it radiates. No surprise.

**Epidemic** · March 5th, 2004, 12:12 PM

A very poor antenna afaik.

A very poor horizontally polarized antenna.

**Solid Snake** · March 5th, 2004, 01:02 PM

I'm sure they'll use reasonable power levels. The signal is strongest right on the wire so it would be smart to use the lowest possible power level to send a clean signal over. Since it's broadband, I'm guessing the signal will be well into the Ghz range. If I'm not mistaken, high freqency signals don't radiate as far as lower frequencies watt for watt. Also, because of the high frequency, the signal would probably be blocked by the earth, buildings or other structures pretty easily.

**Bill in SD, CA** · March 5th, 2004, 01:13 PM

http://www.pcworld.com/news/article/0,aid,115035,00.asp

Bill

**Pexster** · March 5th, 2004, 01:53 PM

lol, Epi! Certainly not MY antenna.

Solid Snake, there is a company here in California that has a 2-20 GHz BPL solution, and if that were what's being proposed, I'd totally agree with you. But the FCC's proposal is for all the other technologies, which use 2-80 MHz frequencies; i.e., right across the entire HF radio spectrum.

**Starfury_2260** · March 5th, 2004, 04:17 PM

I just wish they would get something thats available to rural areas so I can get off this stupid 26.4k dialup!!! If this technology is going to cause too many problems they should drop it and look elsewhere (perhaps that company Pexster mentioned). I want broadband now!!!

**originel** · March 5th, 2004, 05:36 PM

this is an interesting topic considering i am a EE student taking a class on communication systems.

i don't think the phase shift will matter due to the way data like that is passed. unless they are putting a pure digital (unmodulated) into the power lines it seems irrelevant...basically digital data is transmitted using essentially FM with only one of two possible frequency translations. the phase is irrelevant since it is the frequency deviation that determines the signal...ahhhhhh!!!! class is already coming in handy!!!!!