Update on the status of the first large-scale BPL effort in the US: This is the largest commercial rollout of BPL, which delivers data over powerlines by encoding information on high-voltage lines. High-speed broadband can span fairly large distances over existing wires through devices installed at points, which makes it awfully appealing.
So far, estimates--not by the power company, Cinergy--are about 8,000 homes have signed up out of 50,000 which could be served. Cinergy and its data partner Current Communications Group expects to pass 250,000 homes within three years. They aren't giving out numbers themselves, they say, to forestall providing competitive information.
The article opens with line workers installing a bypass box--that's because transformers don't pass the encoded data. Some BPL models use Wi-Fi as the last-100-foot solution, instead of using BPL to the home. This could wind up being a great WiMax/BPL hybrid, too, with WiMax on a certain frequency of poles serving a group of homes.
The utility is starting to gear up using the BPL for its own monitoring purposes, too. In other cases, utilities have worked the other way around, building fiber-optic installations for monitoring that are then turned to the use of broadband for city or for-fee public use.
Some of the think-tanks and analysts who are either opposed to municipally run broadband on ideological, financial, or other grounds are promoting BPL as a method of adding competition without requiring more wire in the ground. But BPL has seen little commercial uptake yet as power companies apparently haven't acted generally interested in it. Related to this is the issue that many electrical utilities are municipal entities, in which case that introduces that element back into their concern about rolling out a network: should they in the current climate?
I find it staggering that after several years of debate on BPL that someone can write an article on the subject and totally fail to mention the principal negative aspect of this invasive technology - namely the fact that it causes interference to licensed HF radio. Whether you're pro or against BPL, any article on the subject that fails to mention this aspect suggests that the author has not done sufficient homework or is biased toward BPL regardless of its spectrum polluting nature.
[Editor's note: If you read the end of the article I link to, it mentions amateur radio and how no effects have yet been seen.--gf]
To the contrary, several BPL trials have been shut down by the operators, partially due to problems with interference to licensed HF radio systems (not only amateur radio services), and because of questions about making the business model work, and delivering relatively slow data transmission speeds as competitors quickly migrate to much higher data rates or technologies (e.g. fiber).
BPL operates by converting data into radio signals that are placed on to electrical power lines. The electrical power line was not designed to act as a transmission medium for radio signals. BPL systems, thus far, tend to operate in the 3 to 30 Mhz portion of the spectrum, also known as "HF" or "shortwave". Some systems may eventually operate up to 80 Mhz.
Because the power line is a poor system for transmitting radio signals, signals leak in to the area around the transmission line, causing interference up to hundreds of meters away. Considering the density of power lines in any suburban or metro area, that means permanent interference problems with BPL. Another, unknown impact problem, is that low, simultaneous leakage from numerous power lines might act like a directional antenna, resulting in interference at great distances from the power lines.
BPL operators are trying, and not always successfully, to mitigate interference by "notching" out the frequencies allocated to amateur radio services. This will not, however, protect U.S. citizens who merely wish to listen to shortwave radio broadcasters. The FCC has also publicly acknowledged the radio interference problems with BPL and has specifically prohibited the use of BPL on certain frequencies and in certain geographic locations where BPL will interfere with federal government communications, including aviation and maritime radio communication systems. If "no effects" have been seen from interference, why did the FCC prohibit BPL systems from its own services?
Visit http://www.arrl.org/tis/info/HTML/plc/
and click on "See video of BPL interference" and then come back and say with a straight face that BPL causes no radio interference what so ever.
(FYI - It would be helpful if your comments system would allow for HTML formatting tags so that this text could be split into separate paragraphs.)
[Editor's note: Line breaks convert in the final posting into paragraphs. Allowing HTML unfortunately has too much abuse potential as has been amply demonstrated in the recent past. Very unfortunate. Thank you for this comment--gf]
Great article (here, and at the Inquirer) But as usual, the ARRL people are crying wolf, wolf, wolf over and over again, since they are starting to become a bit more marginalized.
It's a proven fact that BPL causes interference. Whether it's a minor or a major amount can't seem to be nailed down by either side, but one side (The Hams) seem to be content to keep raising often unreasonable fears and questions, and often seem to be a bit quick fault the technology...
The comments above discussing interference don't take into account the difference between how Current Communications deploys BPL and the technologies most other companies use.
Current employs a hybrid approach using a fiber (and also license exempt wireless) backbone that then delivers the "last foot" using standard home plug gear only from the utility pole to the user.
Here is a link that clarifies this from their site:
http://www.currentgroup.com/LearnMore/Technology/index.html
This is a very different technology than the ones that attempt to use the high tension (and medium voltage) lines to deliver connectivity. These are the technologies that tend to spew interference everywhere.