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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)."
Being near a hot unshielded antenna lead of sufficient power output is bad news...
How can broadband over powerlines be a solution for the 3rd world? Surely you need most people connected to mains power first!
Oh great, now a slashdotting will take out all the power and aircraft in a hundred mile radius
I am one of many. My idea is not unique, nor do I expect my voice alone to sway you. I speak in a chorus of opinion.
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.
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HF radio is *the* communication medium for many life-critical situations. It is the only affordable communication line for many NGOs operating in third world countries, and HF equipment is much easier to setup and more rubust than satellite equipment.
Until now, the HF spectrum has been carefully regulated to avoid harmful interference. It is just not acceptable to sacrifice it simply to get a cheaper Internet access. There are a good set of broadband technologies available which almost do not interfere with HF users.
Let's hope politicians don't wait to do anything until a true emergency happens...
>>esr>>
Seems to be Slashdotted already, even though I'm seeing 0 comments @ -1...
Then again, I didn't think anyone really believed this, did they? I mean, any first-year EE student can tell you that mains cable is no good for signalling on, even at modest frequencies. Bah.
These sigs are more interesting tha
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....
Oh goody so now the power companies will have even more control as they blat out most LF/HF wireless within a certain distance of their transmission lines (or should that be antena lines now?)...
Not to mention won't people who choose not to receive broadband via power still be able to tap into the transmission signal and so monitor other peoples traffic easier than trying to splice into the fiber backbone (oh hang on.... wonder if the gov't might not be keen for this very reason)...
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"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
Yeah, it works. The question is, at what cost?
Do you really know what the amateur radio community does for the public, rtp?
My grandfather was an air-crash investigator, and once investigated a european crash (May have been Switzerland in around 1970, apologies, I don't have any details) in which an airliner had apparently tried to land on the side of a mountain. It was proved that the accident happened due to the local electricity generating grid using high frequency modulation to carry messages over power lines. The chosen frequency was a close enough match to the Instrument Landing System on the aircraft to cause it to engage. I hope modern airliners have better ILS.....
I have been a user for about 10 years. This ends Feb 2014. The site's been ruined. I'm off. Dice, FU
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.
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
Imagine being fried by a stray IP packet
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I know most of the big cities have their power lines underground (at least mine did). The broadband company took it to their challenge to even put the broadband cables underground. I guess that could provide sufficient shield along with the shielding on the cable itself. Now the question is cost of doing this over the entire country, which I have no clue. Again I am just curious as to how will these two cable interact because it is failing my general electromagnetic knowledge.
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
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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."
There's isn't a biological threat from BPL, but the interference issues are very real.
Here's a BPL and Amateur Radio FAQ.
Tired of being "punished" by the Slashdot $rtbl since 2002. I'm now over at http://soylentnews.org/ .
The hazards of RF exposure are still being debated. Hazards from BPL would need years of study. That being said people are probably at more risk from intentional radiators like WiFi points. This is due to the way the body absorbs RF. The absorbtion is a function of the wavelength of the RF and the size of the human body. I don't remember the exact data but the shorter the wavelength the better the absorbtion. This does have some exceptions but I do remember a strong absorbtion around the 1Ghz range.
The interference problem is the greater of the two. Yes it will interfere with radio communications but the interference will be worse for BPL. Aircraft have the potential to cause interference over a wide area due to their altitude, but the tranmitter is relatively low power. The real problems will start when a ham operator can't talk to his buddy 20 miles away. They get tired of the interference so they kick in the linear amplifiers. Since the max leagal power for most of the bands is 1500 watts they have the potential to take out BPL in a very large area.
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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
Here in the New York area, the power company (Con Edison) has a broadband network. You know how they did it?
They used the fact that they already own the poles, to string up their own fiber optic cable.
This, to me, is the primary indication that broadband over power lines just isn't going to happen. When even the power company doesn't believe in it, you know it's a dud.
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More voltage means more bandwidth!
Let me just up the wattage a little bit more!
Ahh! Ahh!
(Slump)
Considering that they have yet to get power to so many of these areas, wouldn't it be wise to run fiber optic at the same time as they run new powerlines?
Oh, how Insightful. I mean, when wiring the third world, obviously money is no problem!
Reality check -- the reason why this is suggested as a solution for the third world is that all they have to do is just run the power cables instead of running the power cables and some other cabling system for phone, TV, and internet. We are talking about people who current can't even afford to run the power cables, much less fiber optic cables too.
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
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.
I agree that MPE limits and RF burns should not be a problem. I'm not sure where the original poster got that from - I also don't see it on the ARRL site.
HOWEVER, the interference concern is VERY real. 250mW can go a long way - I'm not sure where you get your "few hundred meters" figure from. I know people who operate "QRP", a low-power mode, who regularly use similar power levels to talk to ham operators hundreds of miles away!
Let's not forget, a "transmission line" at 60 Hz is much more like an ANTENNA at HF! Powerlines will radiate VERY well.
What's so different about the interference from BPL is that its broadband - that is to say the signal is several tens of MHz wide, spanning all of the HF bands. A spur from another local noise source or unlicensed device is less of a problem because you can simply use another frequency - with BPL this is not possible.
Make no mistake, BPL poses a real problem to HF communication.
there was an emergency training in Linz/Austria.
The training was designed to simulate an major accident (if I remember it correct, it was an explosion of a chemical plant) and to practice the coordination of firefighters, the Red Cross, the police and several other organisations.
Linz, wich has some 18,000 households, is "Austrias powerline city", wich means, it has about 900 working powerline installations.
But these 900 installed plc units were enough to completly suppress the radio units used by some of the participants (e.g. the Red Cross).
These teams had to abandon the training, since communication was near impossible!
Imagine an real accident: No Red Cross or other ambulance teams! (In Austria, the Red Cross still has the major peace of the ambulance-business-pie).
Id rather get hurt on the countryside!
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The FCC has limits to human exposure to RF energy, but broadband over power line that operates at the FCC limits of 30 uV/m at 30 meters distance cannot, under any circumstances, exceed those RF safety standards. On 30-300 MHz, the part of the spectrum with the most stringent exposure limits, the exposure level is at about 27.5 volts/meter -- a level about 120 dB higher than the levels permitted by Part 15 to unlicensed emitters such as BPL. Expressed in power, the BPL systems are permitted to operate at a level that is 1/1,000,000,000,000 of the FCC's exposure standards. The risk to broadband over power lines is that the levels are strong enough to cause harmful interfernce. As a secondary issue, at least one system has been demonstrated to be susceptible to interference from amateur radio and presumably other HF operation. The RF levels of BPL systems are, however, nowhere near the levels that could exceed the RF-exposure limits. Ed Hare, W1RFI@arrl.org