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Could Broadband Over Power Lines be Dangerous?
falconfighter writes " Broadband over Powerlines, once touted as the solution to many internet problems (developing 3rd world countries, etc.) has a new hazard. The system basically involves putting high amounts of modulated RF on a power line. The Amateur Radio Relay League has the most informative page on the topic.
The hazards include exceeding MPE (maximum permissable exposure), RF burns, and disrupting the HF bands of radio. This last one would also work in reverse, meaning hams, airplanes, or the military keying up their radios could take out large areas of internet service (with airplanes, potentially over several hundred miles)."
How can broadband over powerlines be a solution for the 3rd world? Surely you need most people connected to mains power first!
Do note that the problems of interference goes both ways: broadband over powerlines will jam HF communications (including emergency services some places). But at the same time a HF jammer or a HF over-the-horizon radar will jam broadband over powerlines.
HF being global means a jammer in the Pacific can take out broadband in Europe.
...well, mostly. The hazards of RF exposure are controversial at best, with widely varying opinions in the medical community and no real, controlled studies. It's pretty certain, though, that at the low HF frequencies that the BPL folks are proposing, the effects of exposures to a few watts are pretty minimal.
This doesn't mean that BPL is a good idea. As the ARRL (which stands for American Radio Relay League) correctly points out - and has been covered on Slashdot before - BPL is a disaster for HF radio communications. Government agencies are weighing in strongly against it. I doubt it'll see the light of day in widespread use in the US.
Disinfect the GNU General Public Virus!
Having an amateur radio antenna is like a lightning rod for neighborhood electronics problems. I've not transmitted for a couple of years now, but that has not stopped neighbors from blaming me for every glitch that occurs with their electronics. I can imagine what will happen if I key up my transmitter and disrupt every internet connection for a couple of miles....
"Let's put something that looks like high-power broadband RF noise on long, unshielded, untwisted power lines, suspended in the air, otherwise known as antennas."
Mea navis aericumbens anguillis abundat
Hams are more concerned about the interference issue than the health risks, and rightly so. The potential health hazards created by modulating the power lines should be minimal, assuming the level of modulation is kept reasonably low.
The interference caused to more traditional RF communications is likely to be significant because you are, in effect, stringing miles and miles of antenae across the countryside. The best bet might be to modulate on bands that are presently home to digital communication and in coordination with those present modulation schemes such that they don't interfere with each other.
I suspect the whole issue may be moot, as I doubt that BPL will ever see a largescale rollout for other technical reasons besides these.
Being unshielded makes me wonder about the likelyhood of "sniffing" with a receiving antenna and amplifier. It's spread spectrum like the cable 'modems' but ya never know. I'm sure the NSA is ready for any potential rollout.
Trolling is a art,
That is in South Europe, just in case anyone doesn't know, we have broad-band over many companies, but main power-line distributor, Iberdrola, is now starting to offer this service with lower prices than other operators. I was thinking to switch to them since they offer lower prices and better service, and they have even run a test program over a few months in the city of Zaragoza and near country area with no known problems, I'm surprised to see that news here.
DON'T PANIC
From the article, it appears the Japanese already have decided to kill this system.
e ws /jn0208.htm
http://www.jarl.or.jp/English/4_Library/A-4-1_N
Maybe our lawmakers could have their aides read up on why?
And quite dangerous.
I mean, really, who expects this to work
What some power companies here (norway) have done is to use a special kind of machine (it looks like a really clever invention) that "spins" fibre optic cable(s) around high voltage power lines. This doesn't work for buried power cables, ofcourse. This technique gives several advantages: Cheap, the cost is the cable and a helicopter, no digging, no new cable masts, no buying right of way. Security (I'd think twice before trying to mess with a cable wrapped around a high voltage line :D ). And since light won't be disturbed by the magnetic fields generated by the current there is no need to worry about power and data interfering with each other
- We are the slashdot. Resistance is futile. Prepare to be moderated -
The reason is that we take care of the community in case of emergencies. In most cases, if something happens, hams are on the scene within 5 mins. We can relay messages in virtually no time (provided there's no other way to communicate) and basically are just there in emergencies.
"Give a man a fire, he's warm for a day, set a man on fire, he's warm for life."
Hams are "set against this PLC thingie" because it would basically wipe out our service. The ARRL has fought encroachment onto our allocationtions for seventy-five years, and rightly so: ham radio trains young people in electronics and provides a free, emergency communications service that works even when "the grid is down." Ironically, my first exposure to IRC was on a ham TCP/IP packet network.
As far as "no clear TV or radio signal for you" goes, interference cases almost always trace back to poor shielding on consumer electronics devices, not dirty ham transmitters. If your TV can't deal with 1500 watts next door, I'm sure your local ham would be glad to put a passband on it. Which, as a result of ham radio, he knows how to do.
KB3CAX
More voltage means more bandwidth!
Let me just up the wattage a little bit more!
Ahh! Ahh!
(Slump)
I'm not quite so ready to believe the health-realated concerns, but the interference problems that will result from an implementation of BPL are very real. I've seen a demonstration of BPL's interference at a local hamfest here in the Washington, DC area (For those interested, AMRAD will also be giving a presentation at the DC area Winterfest hamfest in February). BPL makes a lot of noise on an HF receiver, across the entire tuning range! But what is potentially even worse is that a relatively small amount of power (I believe they gave the example of 10 watts into a dipole at reasonable proximity) is enough to cause a link to fail.
Undoubtedly, a ham radio operator's neighbors, and perhaps the power company, will put a lot of pressure on him to cease operating a ham radio. This is totally backwards! Let's revisit the Part 15 rules for a minute - the regulations that apply to unlicensed services, including BPL. It says that an unlicensed device MAY NOT cause harmful interference to a licensed service but an unlicensed device must accept any harmful interference received.
This basically means that the burden for resolving any interference problem is on the head of the unlicensed service, in this case, the power company - at least in theory. I have a hard time believing it will play out this way though. In fact, when the FCC asked for comments on a notice of inquiry with regards to relaxing part 15 standards, many power companies claimed that NO INTERFERENCE PROBLEM EXISTS, and it is up to other users to PROOVE it, before they should be required to act on it. This is a total reversal of the roles established by Part 15! And that is leaving aside the fact that there are several studies done by hams, including a very good one from AMRAD, that do proove, both empiracally and mathematically, the interference threat. BPL promoters, including the heads at the FCC, have turned a blind eye.
HF radio is used to provide long-distance communications during disasters by many groups, including ham radio organizations, and FEMA. (FEMA has recently weighed in on the debate) It also carries shortwave broadcast from other countries, which would be sqaushed by interference.
It does not make sense that the FCC should allow an unlicensed user to render this huge chunk of spectrum totally useless to it's intended users. It's selfish and shortsighted.
Please write your congressperson. Make them aware of the problems BPL could bring.