Frequently Asked Questions About

Broadband Over Powerline (BPL)

and Wireless Spectrum Issues

by Anthony Good

Updated 2006-07-02

This FAQ attempts to answer many of the questions surrounding Broadband Over Powerline and wireless spectrum interference issues. I've attempted to target all audiences and keep technical items as easy to understand as possible.  Please send suggestions, comments, questions, or corrections to the email address listed below.   



Q: What is Broadband over Powerline or BPL?

A: BPL is a system that is being tested to provide broadband Internet service via powerlines. Radio energy is coupled onto power lines and is distributed into homes. A device in the home plugs into a normal wall outlet and typically provides an Ethernet connection to a computer or home network.

BPL is also known in some countries as PLT. It can also be referred to as Broadband Powerline Carrier, or just PLC, although the acronym PLC is more applicable to an older technology that is used for telemetry and control in power systems and is not the same thing.

At the time of this writing, BPL is mainly in testing in the United States and a few foreign countries. A few carriers are actually selling the service to customers. BPL is intended as another residential broadband technology similar to DSL and Cable.

The ARRL BPL web page features a number of articles about BPL, including links to tutorials and FCC information.

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Q: Why are Amateur Radio operators, also known as Hams, in an uproar over Broadband Over Powerline or BPL?

A: BPL is a system that is being tested to provide broadband Internet service via powerlines. The system uses radio frequencies that do radiate into the air. They can cause interference to licensed services including Amateur Radio. This interference has been seen and documented in most of the BPL trial areas. BPL experimental licenses have been issued allowing some systems to operate between 2 and 80 MHz (megahertz).  This particular band of frequencies are generally known as HF (which is actually 3 – 30 Mhz) or “shortwave” frequencies.  This part of the radio spectrum has very special properties not found elsewhere. With this band, one can communicate around the world with very low power levels, without the need for any equipment in between, such as satellites or repeaters. This is due to the fact that radio waves in this band can bounce off the ionosphere multiple times to get to the destination. Other portions of the radio spectrum are essentially line-of-sight. This means that the signals cannot bend or bounce off the ionosphere, but they can only propagate like light – in a straight line.  Many consumers have enjoyed listening to shortwave radio broadcasts from around the world.

A summary of the concerns of amateur radio operators can be read on the ARRL web site.

Here is a good visual representation of how much spectrum BPL has the potential to pollute. (BPL is the black “spray paint”)

It's important to understand that Hams oppose BPL interference to wireless spectrum, and do not oppose BPL itself or broadband, despite what several BPL carriers and vendors have said publicly.

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Q: What is technically wrong with BPL?

A: The medium of BPL (the powerline cable), unlike any other broadband medium (copper twisted pair, fiber, coaxial cable), is inherently unsuited for carrying the frequencies BPL uses. Power lines, copper twisted pair, and coaxial cable all act like natural low pass filters, meaning higher frequencies are attenuated more than lower frequencies when attempting to transmit them through the medium. The exact slope of the graph of attenuation depends on the specific construction of the material, but in general, twisted pair is suitable up to 100 Mhz and coaxial cable can go up to about 3 Ghz. Again, these are very general figures and determining the suitability for any application depends on other factors. Power lines would be suitable for up to perhaps 20 Khz, maybe 350 kHz at a stretch, with caveats. The exact figure is unimportant for this discussion, but note that this is kilohertz, not megahertz or gigahertz. These are essentially audio frequencies, and equate to a data rate in the neighborhood of ISDN.

Power lines are designed to carry electrical power.  They were not designed to carry radio signals.  They do this very poorly, loosing much of the signal to losses and, more importantly, radiating them as radio signals that can and do affect nearby receivers using those frequencies.  Amateur radio operators, CB operators and shortwave listeners are all found commonly in the residential neighborhoods where BPL will be installed.  They will all suffer strong interference if BPL uses their frequencies at the permitted levels.  Other uses of HF spectrum include business, government, military and aeronautical. Many of these users and their organizations have expressed strong concern about BPL and its interference potential.

Other wires and cable, such as telephone or cable TV systems do actually radiate to some extent, but in proportion to the amplitude of the signal they are carrying, it is minuscule. (This doesn’t apply to poorly designed or maintained cable or pairs, or intentionally radiating cable like Radiax used for indoor applications). It’s ironic that many antennas used on HF are very close in construction and visual appearance to typical power lines.  It has been clearly demonstrated in technical studies prepared by ARRL, the National Organization for Amateur Radio that BPL often causes interference and that power lines act like antennas.

Putting a signal that will operate 24 hours a day over  wide range of frequencies at the FCC limits for unlicensed devices onto wiring that radiates well is a very poor engineering choice.  When that system is built as large as an entire community – or several states –noise and  interference are inevitable.  Basic first-year college courses teach one this. This is very, very basic. The electrically dirty and unpredictable nature of power lines can also produce harmonics and intermodulation that can cause unexpected forms of interference.

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Q: Does BPL work?

A: From a consumer point of view and what has been heard from test areas, yes. Amateur radio operators and others do not have an issue with this.  So far, the BPL systems installed are generally small, and how well they will work when built out to cover a wider area and more customers remains to be seen, though, as there are few if any heavily loaded systems. However, one would expect the behavior of a BPL network to resemble that of a shared medium like cable or wireless. Systems will have to be segmented further as traffic grows and the available bandwidth in a segment decreases.

There are significant concerns about immunity to interference which are discussed later in this FAQ. Tests done to date show that nearby radio transmitters can interfere with BPL, but this too, needs to be looked at in larger systems. The effects of such interference are unknown at this point and could make BPL service in areas unreliable or unfeasible. Under the FCC rules on BPL, as an unlicensed device, BPL is offered no protection from licensed users that may interfere with BPL in the normal course of their licensed operation.

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Q: What are the benefits of BPL?

A: The dream of BPL is to have every powerline activated with BPL and have BPL networks within homes. With the advent of inexpensive chipsets, every appliance in the home could easily be networked without additional wiring. Utilities could use BPL to manage network elements within the power grid and perform automatic meter reading or AMR, although narrowband non-interfering PLC based AMR system existed previous to BPL and continue to be in use today. Grid management functions could be performed as well, although PLC and SCADA systems do this today.

One major perceived advantage of BPL is wiring infrastructure. Utility power is nearly everywhere, so costly copper twisted pair or fiber would not have to be run. While this may be seen as a major advantage, the work and cost to light up every power line with BPL is significant.

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Q: Is BPL the same as wireless broadband?

A: No. BPL affects wireless radio spectrum but it does not actually use the wireless spectrum through the air to transmit data. There are some BPL systems that use unlicensed 802.11 WiFi wireless as part of the BPL system to deliver the data to the end user, however the core BPL network uses the powerline as the base medium for transmission.

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Q: Why can’t BPL coexist with wireless technologies?

A: To allow a wired-based network to make large portions of frequencies unusable in the RF world is tantamount to the way industry used to be permitted to cause serious pollution. Cable companies use frequencies in VHF and UHF bands that were they to leak out into the outside world, would wreak havoc with aviation and public safety frequencies. They are subject to strict limits that include a need for them to regularly test the cumulative effect of the leakage from their system and there’s no reason why any other wired network like BPL shouldn’t be subject to strict limits – it’s a wired medium, it is not necessary for it to affect wireless media in any way.

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Q: Is BPL new?

A: BPL has been tested and deployed on a limited basis in other countries. BPL vendors may claim “new technology” and advances have now made it possible, but the fact is they can’t change the laws of physics. High speed data must occupy a certain amount of “bandwidth” and power lines which were designed to operate at 60Hz will radiate RF that is applied to them. The BPL system has to operate at a higher level than the noise on the lines, so by definition, BPL will increase the radiated noise level from the power lines that carry it, on any spectrum it used. Only changing power line construction (i.e. coaxial cable) would eliminate this radiation. BPL proponents reject this as being too costly, but that would be the cost to make this a real viable technology.

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Q: Hasn't Power Line Carrier or PLC been in operation for years without problems?

A: The “original” PLC is a very low frequency, narrow bandwidth signal used for control equipment in the power grid. It is in the neighborhood of 100 to 180 kHz (that's kilohertz, not megahertz). It is not intended for high speed data transfer, but rather simple commands, like “turn relay on”, “turn relay off”. It is also used to send “messages” up the line when a major failure occurs so that other network elements don't trip off when senses a fault. This keeps the power grid from falling down like a bunch of dominoes (like what happen recently with the blackout in the Northeast :-).

Usually people refer to the 1-80 Mhz “PLC” as BPL, although some use the acronyms interchangeably and in my opinion, wrongly. Comparing "original" PLC and BPL is like comparing apples to oranges. PLC is brief, primitive commands and is very narrow banded. BPL is wide band noise that's all over the place.

Recently the Amateur Radio community petitioned the FCC for a low frequency band in the same area as the original low frequency telemetry PLC. It was rejected by the FCC because utility companies complained that Amateurs would interfere with this telemetry PLC. This is very interesting for several reasons. First off, the utilities are saying that BPL won't interfere with Amateurs and Amateurs won't interfere with BPL. But PLC is arguably more robust than BPL because it's narrow band. So which way is it ? The second reason this was so interesting (or disturbing) is that telemetry PLC is operating under Part 15 and is afforded no protection from interference from licensed services. For the first time the FCC disallowed licensed operation and essentially protected a Part 15 operation. This sets a dangerous precedent as any unlicensed "spectrum squatter" can later claim rights to a chunk of frequencies. The third and even worse observation is that the utilities have admitted that the telemetry system of the national power grid is vulnerable to attack, and they've based a critical part of the infrastructure on something that cannot be legally protected from interference. Any nutcase with a little knowledge could conceivably control network elements within a power grid with enough time and money.

PLC has been in operation for a long time, but as I mentioned, it's very different from BPL. It seems many BPL proponents are confusing the situation by riding on PLC's history and merits.

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Q: Haven't power lines always radiated radio energy and caused interference?

A: Previous to BPL, power lines have had a history of radiating noise, but properly maintained lines will radiate only a minute amount of radio energy that is low enough that it does not impact radio communications. On the other hand, a properly maintained BPL system will radiate radio energy.

A distinction between power transmission noise and BPL noise needs to made, and is very important to understanding this issue. Power transmission noise is a product of 60 hertz voltage and is a rough, raspy frying type of noise that is stronger at low frequencies and gradually tapers off. Two types of BPL noise exist. One is results from Spread Spectrum modulation which is a Geiger counter type noise. The other type of BPL noise typically observed is resulting from OFDM modulation. This creates carriers, or little “radio blips” every 1 kilohertz or so across the radio spectrum. Each “blip” has a ringing sound or clicking sound.

Power transmission noise can most always be fixed by changing out worn or defective power line components such as insulators or taps. Radio interference from BPL is a side effect of a the system in operation, not an anomaly.

Ironically, BPL proponents and FCC representatives have claimed that BPL deployments have reduced classic power line transmission noise. This is true to an extent as any noise on the line from power transmission will seriously degrade a BPL signal. Unfortunately, the power line transmission noise is being replaced with a much more devastating signal that is stronger and does not decrease in strength as you go up in frequency.

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Q: Does replacing bad or dirty insulators on the powerline fix the BPL interference problem?

A: Replacing such components reduces power transmission generated noise, but not the BPL interference. Often new BPL carriers have to clean up their lines and reduce the power transmission generated noise so BPL will work. BPL is a radio signal on the powerline, and basic electronics theory states that any unshielded conductor a ¼ wavelength long will radiate RF energy.

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Q: BPL seems to be more prevalent in Europe. Is BPL interference just a problem in the United States? Is the interference issue related to North American 60 hertz systems versus 50 hertz systems found in the rest of the world?

A: The BPL interference problem is a function of the unshielded powerline, not the frequency of the power signals, 50 or 60 hertz. European systems (50 hz) tend to be better suited for BPL than North American systems (60 hz) from a logistical point of view as utilities in Europe tend to place tens, or a hundred or more customers on one transformer. In the US there is usually only two, three, or four customers on one transformer. Because European voltage service to the home is 240V versus North American 120V service, the I2R losses in transformers and drops in Europe are one quarter that of North American systems, thus more homes can be placed on one transformer. More customers on one transformer translates to less transformer bypasses that are needed to pass the BPL signals to household wiring.

Again, the feasibility of BPL service is not related to power service frequency.

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Q: Won’t adaptive technology in BPL protect others from interference?

A: Adaptive technology was proposed by the FCC in the Notice of Proposed Rulemaking in 2003 as a way to mitigate interference. While sounding high tech, this technology is actually administrative functions that are present in most BPL equipment today. This includes:

·       Power control, dynamic or remote

·       Frequency notching

·       Harmful interference shut-down feature

 

First off, these techniques do not provide any protection for mobile or portable stations. Dynamic power control is an obvious no-brainer and should be a requirement as this would keep power levels on the lines as low as possible. Frequency notching, while a possible solution for local interference complaints, doesn't address long range interference that would be created by ionospheric propagation or the cumulative effect on the noise floor in the HF bands. The harmful interference shut-down feature is rather ambiguous in the NPRM, but it seems to be a manual remote control on/off switch. Most network equipment today can be turned off remotely, so this feature isn't a real stretch, but it does nothing proactively to lessen interference.  Also, many uses of shortwave involve more listening than transmitting, and uses like international shortwave broadcast would not have any transmitters nearby for the BPL system to sense. 


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Q: If this just affects Ham Radio, why should anyone care?

A: BPL will also affect other licensed services such as government agencies, military, aviation, maritime, public safety, and shortwave broadcasts. Ham radio occupies less than 10 percent of the affected radio spectrum.  Many of these users have filed comments in the FCC rulemaking, in both the Notice of Inquiry and the Notice of Proposed Rulemaking, that expresses grave concern about BPL interference.

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Q: Are Hams qualified to talk about BPL issues?

A: Hams are licensed by the FCC in the United States and various governing bodies in most every country in the world. Most countries have several classes of licenses. In the United States and most countries, one must pass written tests on electronic theory, communications protocol, and regulatory material. While becoming a licensed Ham isn't equivalent to an Electrical Engineering degree, many hams have formal educations in electrical engineering.

The experience and knowledge of Hams can vary greatly, and like any hobby or profession, there are hams who speak before thinking. Occasionally you will find an ex-ham dismissing Ham Radio as being dead, or an inexperienced Ham who only uses VHF bands who could care less about the HF bands that are threatened by BPL. Most active hams though are rather knowledgeable.  Their decades of experience on radio give them an understanding about interference that is unmatched in any arena.

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Q: Why are Hams the only people talking about the negative affects of BPL? Why aren't other services complaining?

A: Ham radio occupies a minority of BPL spectrum, with government, shortwave, public safety, and ship communications occupying the majority. Ham radio operators are the most vocal because government agency employees quite simply don’t post in Internet forums. Many of these other users are concerned about BPL interference. Comments with the FCC have been filed from groups and agencies like the NTIA, Salvation Army, the Missouri State Patrol, Aeronautical Radio, Inc, and NPR, to name just a few.

Most of the other services on HF radio frequencies affected by BPL like government and aviation usually operate at much higher power, use much larger/more directional antenna arrays, are more frequency agile, and often have their transmit/receive stations at sea, in the air, or on remote reservations of land far away from civilian housing areas and their associated power lines. In the latter case, having acres and acres of open land gives much more flexibility about antenna placement than someone living on a 1/4 acre residential lot. Full realization of each of these advantages is not attainable by even the richest radio amateur. So even if government agencies such as the NTIA say that BPL will be of minimal impact to them, it should be emphasized that their capabilities, and therefore their operating environment, may be very different than that of amateurs.

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Q: What other services use the HF radio spectrum?

A: A good web page with a sampling of non-Amateur frequencies is here . This is just a sampling of 1000 frequencies of interest and not a complete list of allocations. A chart of allocations from a “30,000 foot” view is here .

Q: How can HF radio signals travel across the world?

A: Long distance HF propagation occurs by radio signals bouncing between the earth and the ionosphere, often several times.

This has two consequences with regards to BPL. A lot of long distance wireless HF communications occurs just above the noise floor (the common noise you hear on your radio when you are not receiving a station which is noise leftover from the Big Bang and from various man made sources), receiving very weak signals. A station attempting to receive an HF signal could experience interference from a local BPL system, even if it is notched in the amateur radio bands and 40 or 50 dB below the emissions limit. (A good analogy is it's hard to hear someone yelling a half mile away when someone is wispering in your ears). The second issue has yet to be proven either way, but with thousands or millions of BPL devices in operation, the noise from these devices combine could raise the noise floor in the HF spectrum and propagate thousands of miles. The jury is still out on this and the NTIA was supposed to release a second study that would explore this. There's not nearly enough BPL systems in operation to test this in real world circumstances.

Q: Isn't long distance HF communications more an infrequent anomaly rather than a common occurrence?

A: HF propagation in an area varies on the time of day and on solar activity. It's usually possible to communicate on some HF band to various places in the world 24 hours a day. During the day, the D, E, and F layers form a thicker layer of ionization. This ticker layer absorbs lower frequencies (below 5 Mhz or so), and enables farther propagation of frequencies between 15 and 30 Mhz. At night, the D, E, and F layers combine. This causes the upper frequecy limit (called Maximum Usable Frequency or MUF) to drop, usually to about 14 or 15 Mhz. During this time, frequencies below 5 Mhz will propagate better. This is why you can hear many AM broadcast radio stations at night, and most AM radio stations decrease their power at night to avoid interference.

Q: Why doesn't my 802.11 WiFi or cellular phone radio signal travel around the world?

A: 802.11 WiFi uses 2.4 Ghz frequencies (2400 Mhz) which is considered microwave frequencies, cellular is 800 Mhz, and PCS is around 1.3 Ghz. These to not bounce off of the ionosphere, but travel right through it. The reflective characteristics of the ionosphere diminish above about 30 Mhz. Also, microwave frequencies are much more susceptible to absorption by precipitation and water vapor.

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Q: Does BPL Affect Shortwave Listeners (SWLs) and Shortwave Broadcast Frequencies?

A: Yes, BPL can affect all of the HF shortwave broadcast bands.

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Q: Can’t Hams and others using the spectrum simply be relocated?

A: Users of the affected spectrum cannot be relocated, or at least not economically or in a timely manner. It would be cheaper for the government to subsidize cable and DSL deployment. Plus, all of the services that use HF bands require the characteristics that only HF bands exhibit. There would also be huge international treaty implications with any relocation. Changes in international communications treaties are measured in decades, not months or even years. Relocating government and military services alone would take years as the FCC would have to structure a migration plan. Chances are it would be ten years before this could be completed and it’s likely that power companies will have run fiber to the home or DSL and cable will finally be ubiquitous. Perhaps the largest issue to tackle, though, is where to move these services in what is an already overcrowded spectrum.

If it was determined that relocation was the way to go, this would be very irresponsible as HF radio bands are a unique natural resource. No other radio spectrum can provide worldwide communications without any supporting infrastructure (i.e. satellites).

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Q: Why doesn't the FCC allocate dedicated spectrum for BPL?

A: There are two main reasons for this. The first is quite simply there is not enough open space in the HF spectrum to accommodate a dedicated allocation for BPL. Current BPL systems need at least ten MHz of spectrum. Newer, faster systems may need 25 MHz or more to operate. Accommodating such systems would require the entire HF spectrum to be allocated to BPL. The second reason against a dedicated frequency allocation is that BPL doesn't actually use the wireless spectrum, it emits energy in the frequency range, thus polluting it. An analogy would be building a highway and dedicating it to one industry or group of people so they could dump garbage on it.

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Q: Won't Frequency Notching protect licensed services?

A: Frequency Notching is a new feature that is reported on some of the second generation BPL systems. The idea is that if a BPL signal is interfering, the system can be configured to not use this frequency or a band of frequencies. This apparently can be done on a subscriber, network, or system wide basis. While this is a nice feature, it still doesn't make BPL acceptable for four reasons. The first of which is that the possibility of intermodulation still exists. (Intermodulation is described in detail below).

The second reason is that BPL signals can propagate for very long distances due to the characteristics of the frequencies they are using. Interference from a BPL could be experienced a thousand miles away. Tracking this interference down so that the BPL operator could be informed of a Part 15 violation in order to get them to notch the frequency would be logistically difficult. Considering BPL acts like a large distributed antenna and not a classic point-source of interference, it would be hard to direction find the signal to track it down.

The third issue is what's called the noise floor. The noise floor in simple terms is what you hear in between radio stations on an FM or AM radio. It's the snowy screen you see on your TV when there's no station on the channel. The noise floor is essentially noise and radio spectrum energy left over from the Big Bang. This noise is fairly constant, but man-made noise sources such as existing 60 Hz power lines, noisy transmitters and other things contribute to raising the noise floor. BPL systems will contribute to the noise floor and raise it higher. This will make it more difficult to receive weak signals. Taken to the extreme, the raised noise floor could make HF communications impossible.

The fourth reason that notching won't work is that there just isn't any significant open space in the HF spectrum. Anywhere you look, there's a service using the frequency. My guess is BPL providers are banking on the fact that there's not a local user of particular chunks of HF frequencies, so they will configure their systems to operate in these areas. If we were talking about microwave frequencies that are strictly line-of-sight propagation bands this would be a great solution, but that's simply not the case with HF. HF has worldwide propagation characteristics, so it's likely users hundreds or thousands of miles away could experience interference. As mentioned elsewhere here, tracking such wide band no identification interference is nearly impossible.

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Q: What is intermodulation?

A: Intermodulation is the mixing of radio signals which produces new radio signals. Think of it as radio waves having children. But just how do radio waves have children ?

This mixing is caused by what are called non-linearities. One non-linear electronic component that you find in most any electronic device is a diode. When multiple radio signals are run through the diode, they mix together. Let's say we have a 4 Mhz signal and a 6 Mhz signal going into the diode. We would then get:

4 + 6 = 10 Mhz

6 – 4 = 2 Mhz

4 and 6 Mhz had two “children”, 2 and 10 Mhz !

Now, non-linearities are usually good. This phenomenon is used in just about every radio device to either create a signal to be transmitted, or receive a signal that you hear or see. But, non-linearities can occur where you don't want them and then in causes problems. One such place is in power lines. Bad, corroded connections or dissimilar metals touching can create natural diodes that act like mixers and produce this intermodulation.

So, let's take a BPL signal and for the sake of discussion, say it's a grossly simplified consisting of radio signals at 1, 5, 8, 9, and 12 Mhz. Some of the intermodulation products that could be created would be:

1 + 5 = 6 Mhz

8 + 9 = 17 Mhz

9 + 12 = 21 Mhz

12 – 9 = 3 Mhz

But you could also have what is known as third order products:

1 + 9 + 12 = 22 Mhz

8 + 9 + 12 = 29 Mhz

8 – 5 + 12 = 15 Mhz

Or even:

2 * 12 = 24 Mhz

(9 – 5) * 12 = 48 Mhz

You can do the math and figure out each permutation, but you get the idea. If we took a real BPL signal that has signals from 1 – 80 Mhz the number of products and where they would fall are mind-boggling. The resulting intermodulation products in a system could extend well above the band BPL proponents want, falling into FM broadcast, VHF TV, Aeronautical, and more public safety bands. This is just another reason why BPL is so problematic.

It's arguable that such non-linearities in power lines are exhibited as arcing connections, something that most power companies are actively searching for these days as the RFI (radio frequency interference) effects are well understood. These maintenance issues will be addressed quickly by well run utilities. However, non-linear loads are common in homes, light dimmers being the first devices that come to mind. Theoretically, these devices could create intermodulation that would in turn be radiated by the house wiring and outside power cabling.

An article explaining intermodulation in more detail can be downloaded from the ARRL web site.

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Q: What are harmonics?

A: Harmonics are in the same “family” as intermodulation. It's new radio signals that are created by a non-linear device that are a multiple of a radio signal. Unlike intermodulation which requires two or more “parent” or fundamental signals to be created, harmonics are the product of just one signal. A 10 megahertz signal would have a second harmonic of 20 Mhz, a third harmonic of 30 Mhz, a fourth harmonic of 40 Mhz, and so on. Harmonics created in equipment are generally undesirable and can interfere with other communications services if not filtered out. Harmonics can also mix with other signals to form intermodulation.

Harmonics can be created from fundamental BPL signals on powerlines. These have been observed in the field at typically 30 dB lower than primary BPL signals.

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Q: Isn’t ham radio on the decline?

A: Ham bands are not deserted and ham radio is not dying. Ham radio has more licensees than ever. Ham opponents post comments that every time they’ve listened to ham radio, it’s been dead. You never hear any details. Was it HF, VHF, UHF? Were they listening on a band that is subject to the effects of propagation which change based on time-of-day and solar conditions, and were just listening to a band that was dead due to radio conditions? They don’t know. But in this online world, anecdotal evidence seems to carry as much weigh as a ten year study. It should be noted that on many weekends, it can be difficult to find an open, unused frequency on several HF bands. Statistics on the number of ham radio operators in the world is here .

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Q: Isn’t ham radio obsolete?

A: It depends on what you call “obsolete”. Hams use numerous modes including CW (Morse Code), Voice (AM, FM and Single Sideband), Video (analog slow scan and fast scan), and data (RTTY, PSK, MFSK, Spread Spectrum). Morse code has been around since the beginning of radio and still thrives as a nostalgic part of the hobby today. Other Hams experiment with cutting-edge modulation techniques, while others prefer older modes. Many Amateurs build their own equipment from scratch. Internationally, Ham Radio also has several satellites orbiting the Earth.

Electronics engineering basics such as antenna design, modulation techniques, amplifier design, filter design, and transmission line theory never really change, and in Amateur Radio you can learn about these and actually see them in action, and not just read about it.

While Amateur Radio in general isn't “cutting edge” like it was in previous years, it provides an educational foundation for engineers who will be designing cutting edge technology in the future in the professional world, so to dismiss it as “obsolete” is misguided and narrow-minded.

Ham radio also provides emergency communications services in times of need.

Amateur Radio has continued to thrive through the advent of long distance telephone, satellite, pagers, cell phones and now the Internet, and it will always have a place whether for hobbyist, public service, educational, or international goodwill purposes.



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Q: In a disaster when the power goes out, BPL goes out, but so does Ham Radio as well. So what use is Ham Radio in a disaster?

A: Amateur Radio operators pride themselves in emergency preparedness and many are equipped with significant emergency power capabilities and portable low power equipment. There’s an annual event called Field Day in which this emergency preparedness is exercised and improved.

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Q: But cellular and/or satellite provides disaster communications, so why is ham radio needed?

A: Cellular networks rely on telco facilities to deliver calls to cell sites. Many carriers do use Part 101 point-to-point microwave instead of telco facilities, but this has largely given way to telco facilities especially in core metropolitan areas where cell densities make microwave prohibitive. So cellular networks are often subject to the same negative impact as wired telco facilities. Additionally, during a disaster, if a portion of the cellular system remains in operation, many times it is so overloaded that it is nearly useless. While ham radio can’t carry an onslaught of phone calls, it is useful in delivering messages across the country and world. Some of these messages may be a simple “I’m OK” type message from one family member to another and seem insignificant. But, if you’ve ever been in the situation on the other end waiting, you know such an insignificant communication is priceless.

Satellite technology for voice use is expensive and its use is far from ubiquitous. Ham Radio provides infrastructure-free, inexpensive, low bandwidth, reliable communications. Even if satellite phones become affordable and commonplace, Ham Radio has value as a backup system and to augment communications capabilities when cellular, telco, and satellite networks become overloaded or non-functional.

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Q: If the power goes out in an area, BPL interference will go out as well, so Hams could then provide emergency services, so what is the problem?

A: Amateurs need to maintain equipment and practice needed skills before a disaster occurs. If the equipment is unusable during regular times, what is the motivation even to buy equipment? Another thing to consider is that emergency stations need to be able to communicate out to areas that do have power.

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Q: Why can't a national “off switch” for BPL be implemented so that during times of emergency BPL could be deactivated allowing interference free radio operation?

A: This makes an assumption that only emergency HF communications are needed and normal day-to-day communications are not. This is not the case. Looking at this sampling of non-Amateur HF frequencies, there's a massive amount of day-to-day communications for aeronautical, military, and other government agencies.

Assuming for a moment that we could live with only emergency communications and were going to implement a mechanism to turn off all BPL on command, the logistics of such of system would be staggering. Who would trigger such a switch? If it was a linked system, how would it be secured? What if companies wanted to legally challenge activations as any activations of the system would impact their bottom line?

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Q: Are the American Radio Relay League or ARRL and/or Hams really representing the telephone companies,  cable companies or and other commercial interests?

A: The ARRL is non-profit and represents ham radio in the US.  Its members are people with an interest in amateur radio. Their  members’ concerns have been as individuals, the telcos and cable companies are interested in stopping BPL as a competitor, and hams are not concerned about that one way or the other.

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Q: Is the opposition to BPL interference well funded as I've seen journalists and BPL vendors write?

A: Most BPL interference opposition has come from Amateur radio operators in their spare time using their own resources. The ARRL has had a spectrum defense fund for years, but it's a non-profit organization.  ARRL did have a special fundraising to help defray its costs doing studies, visits to the FCC and related costs. It raised about $300,000, which pales in contrast to the real big dollars that the industry it trying to make.  ARRL has spent more than it raised by quite a bit, as the numerous engineering studies it has filed with the FCC can attest.

Arguably, BPL interests like Amperion, Ambient, UPLC, APPA, PLCA, PPL, Progress Energy, Con Ed, some of which are public companies with considerable political clout and deep pockets are much better positioned to move forward their agendas than the ARRL and Amateurs.

The fallacy that BPL interference opposition has been a lucrative well-funded movement appears to have started in 2003 when the US interference debate started and was introduced by a BPL advocacy group (Comments of UPLC's Brett Kilbourne to Morning Call September 28, 2003) .  That misdirection is still being provided by them to journalists today.

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Q: But BPL complies with FCC Part 15, doesn’t it?

A: Deployed BPL systems must comply with the FCC rules under Title 47 Part 15, but those rules set absolute limits for radiation from BPL systems and they have a requirement that no unlicensed device is permitted to cause harmful interference to licensed radio services.  Part 15 also states that the unlicensed device must generate no interference and accept all interference from licensed services with no recourse. Power companies in general have a particularly poor record in responding to interference from their existing 60 Hz power transmissions. Even if a BPL system is compliant with the Part 15 emissions limit, they will have to cease operation if the network is interfering with a licensed service.

BPL vendors in the past have proudly released press releases stating Part 15 compliance, as if this proves evidence of no interference. This is simply not true, as the numerous reports about interference can attest. Their claim that they meet Part 15 really means that they have merely measured that their signal emissions are within mandated limits. In the HF bands, the emissions limit is 30 uV/m (microvolts per meter) at a distance of 30 meters. It's not important to know exactly what this means, but know that this signal level will cause interference in any well designed HF radio equipment. Once interference is detected, the second clause in Part 15 goes into effect, and the system must cease operation regardless of compliance with the mandated emission limit.

Part 15 compliance or certification should not by any means be considered a milestone for product success or investment.

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Q: BPL is being tested in several areas. Shouldn’t the negative affects be seen in these test areas?

A: BPL tests in the United States haven’t been widespread enough to fully understand the implications. Experiments have been mostly on a street or city block level.

A significant number of measurements have been taken by Amateurs and are available in FCC NOI and NPRM response filings.

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Q: If the interference problem is not solved and this is deployed, what will happen?

A: At the time of this writing, several equipment vendors have improved their frequency notching capabilities and are working with the Amateur Radio community. Others continue to deploy systems with inadequate notching or unconfigured notching. Those systems that have interference issues will continue to be dogged with complaints and issues.

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Q: Won’t BPL create more “effective bandwidth” out of what limited resources we have?

A: BPL is a wired network impacting wireless radio spectrum. Wired networks are intended to do just the opposite – not impact wireless frequencies. One wouldn’t run a wire to a car or SUV to provide mobile phone service to that vehicle. And deploying BPL actually exacerbates the ongoing radio spectrum congestion problem, and does not create any additional “overall bandwidth” in the world. And as I mentioned before, relocation of existing services in the HF band is a very, very monumental task taking years of work and substantial costs that have not yet been identified.

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Q: Don't these new modulation techniques like OFDM reduce or eliminate interference ?

A: While techniques like OFDM may change the distribution of radio energy across the radio band in use, it will not reduce interference. Consider this analogy. In a restaurant at a table next to you, if someone speaks loudly in English, and then changes to French or German, the voice still speaks at a certain volume and can interfere with your ongoing conversation at your table. Ignoring that the human brain can naturally block out foreign languages, different languages may change the tonal qualities, but the overall amplitude of the sound waves is still the same.

BPL equipment designers are limited to an emission level of 30 uV/m at a distance of 30 meters. They are naturally going to run the highest power level possible on the line, staying withing this emission limit. The higher the signal level, the less repeaters are needed and it makes the system more economically viable. So, running different modulation schemes will result in the same 30 uV/m emissions level.

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Q: Aren't interference problems with BPL a thing of the past as first generation systems had problems, but the second generation systems today have fixed the interference problems?

A: Regardless of the modulation technique or feedpoint technology used, the base medium is still unshielded power lines which will radiate on whatever frequencies are used in the system. Two equipment vendors, Motorola and Current Technologies, have shown systems with superior frequency notching capabilities and are much more proactive in preventing interference problems.



Q: How else can power companies get into broadband? Isn’t this their only choice?

A: Power companies should be building for broadband dominance in the coming decades and beyond with viable technology like fiber, not for the next year or two with doomed-for-obsolescence technology. If the utility companies are in a frenzy to get their proverbial “foot in the door” before telcos and cable companies snatch up their potential customers, fiber delivery to the last mile and 802.11 wireless on poles for the last 100 feet makes a ton of sense. This is not a new idea and some carriers are doing it now.

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Q: Doesn’t the need for broadband outweigh the needs and value of ham radio and other services using the affected spectrum?

A: Destroying a large portion of wireless spectrum is not justifiable because it benefits more people. There are many examples of this in society where reallocation of a resource would benefit more people, but it would be detrimental long term to the people and the resource itself. Right now, amateur frequency allocations belong to the people internationally. You can enjoy them by simply passing a test and getting licensed. Once they are given to a business interest, they cease to be yours and you can only use them as a customer of that business. BPL impacts other groups including government, military, shortwave, aviation, maritime communications, and CBers, so this would have national security and international implications as well. BPL has been linked in some rhetoric with increasing “homeland security”. BPL in fact takes spectrum away from government agencies directly tasked with protecting the country. So in summary, allowing BPL will ultimately benefit a few utility companies, not the people.

Something that should be kept in mind that people need broadband, not necessarily BPL, and BPL is not the only way to deliver broadband. The barriers to broadband deployment in the US have been political and economic barriers, not technological. One could argue that technological limitations tie directly to economical issues, but BPL ironically technical issues with BPL make in uneconomical in rural areas.

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Q: Why would anyone propose a broadband system that isn’t viable?

A: Potential revenue, an FCC that is very pro-big business lobbyist friendly and technically lacking, a high demand for broadband from a starving public, and the classic promises of broadband and hype are driving BPL.

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Q: Won’t BPL give me cheaper broadband?

A: Perhaps, but the costs to deploy BPL are still there. Repeaters and the BPL equivalent of DSL DSLAMs will need to be deployed. BPL promises to deliver broadband in areas that cable and DSL don’t so there will be no competition to drive down prices. The costs to deliver to these less populated areas will be higher, so the motivation for low prices in these area is absent. But it’s likely BPL will be deployed exactly where cable and DSL is now because that’s where the revenue is.

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Q: Why won't BPL be economical in rural areas?

A: Let's do the math for 10 people per mile of powerline with BPL...

Assume:

CPE cost: $500 each

Repeaters: $1K each

Customer Take Rate: 30%

Backhaul cost: $1k per month (a T1)

Repeater distance: 600 feet

Feedpoint cost/misc routing equip: $5k

Revenue per customer per month: $40

So:

Number of repeaters needed: 8

Number of customers: 3

Nonrecurring cost: $14.5k

Nonrecurring costs over two years: $604 per month

Recurring Cost: $1k per month

Revenue: $120 per month

Mind you this is a quick back-of-a-napkin model, but it's easy to see that rural BPL isn't profitable.

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Q: What is 802.11 / WiFi / 2.4 Ghz / 5 Ghz High Speed BPL?

A: This is a type of BPL which uses frequencies at 2.4 Ghz or 5 Ghz (microwave frequencies) and not HF frequencies and has been developed by a company called Corridor. It should not interfere with licensed services such as Amateur Radio in 1-80 Mhz. Amateurs have a secondary allocation at 2.4 Ghz, but have been living fairly harmoniously with unlicensed 802.11 operations there. The propagation of 2.4 and 5 Ghz is much, much different than that of HF. Such frequencies will travel only a couple miles and is strictly a line-of-sight. HF spectrum can travel around the world with only milliwatts of power making any BPL operations in this band troublesome.

The BPL that occupies 1-80 Mhz is a train wreck technologically and will be problematic for everyone involved.

(Corridor has abandoned Internet access and is now focusing on mobile applications.)

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Q: What about HomePlug devices? Do they prevent interference?

A: HomePlug is an industry specification for in-building BPL devices. They were originally intended to network computers within a building but they can and are being used as part of an access BPL system. As the HomePlug standard was being developed, HomePlug worked with ARRL to assess the effectiveness of "notching" the US Amateur bands in place at the time. The end result was that HomePlug chose not to use Amateur spectrum in their product specification.

HomePlug presently operates between 4 and 20 MHz, with the ham bands except for 60 meters notched. (At the time the specification was developed, 60 meters was not an amateur allocation.) HomePlug and ARRL recognized that this would significantly reduce the interference potential from HomePlug devices, although some potential for interference still remains. HomePlug is working on a new specification -- HomePlug A/V, which will operate much faster and extend upward in frequency to somewhere near 30 MHz. They have discussed this with ARRL and both organizations have agreed in principle that joint testing will be done to assess the impact of this product on Amateur Radio spectrum.

From a ham radio point of view, HomePlug's move in the right direction is appreciated. HomePlug devices are notched in the ham bands and the emissions from them are generally localized in nature, radiating from the wiring of the building where they are installed and to some extent from any overhead 220-volt lines. This gives HomePlug a much more localized interference potential than access BPL, which is placed on the long medium voltage lines in a way that incidentally has the greatest emissions potential.

However, their "notching" is about 30 dB. This means that if a neighbor of a ham a half-a-block up street is using HomePlug, the amateur will probably not hear it. But if an adjacent neighbor is using a HomePlug modem, or any nearby home on the same secondary of the utility step-down transformer, some interference on amateur spectrum is almost inevitable, although at a moderate level. At this time, no HomePlug manufacturer has any solutions should such interference be reported.

HomePlug also does not protect any other spectrum. It operates at Part 15 levels, so on HF, S9+ noise on WWV and international shortwave broadcasting will occur locally near HomePlug devices when they are being used. Fortunately, at least in most implementations, they are quiet except when in actual use, so harmful interference will occur only at times that the HomePlug device and Amateur or shortwave listener are using their receivers at the same time.

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Q: Is 200 Mbs BPL for real?

A: 200 Mbs BPL is in development by DS2 and Homeplug (currently DS2 is ahead of Homeplug in developing a 200 Mbs system). At the time of this writing I'm aware of one underground 200 Mbs commercial system in the US carrying customer traffic. One has to ask how this can be viable. 200 Mbs of BPL bandwidth with an 8 bits/hertz efficiency rate would require 25 Mhz of spectrum free and clear. Current BPL systems using 3 or 4 Mhz channels have had interference complaints lodged. Finding 25 Mhz in the real world is difficult, and spectral efficiencies as high as 8 bits/hertz are extreme optimistic.

It should be noted that 200 Mbs BPL would be the backbone bandwidth an not the actual bandwidth that would be delivered to the end user.

Q: Can't BPL go to 1 Gbs?

A: A study conducted by Penn State (funded by AT&T while they were involved in BPL) showed that BPL could achieve speeds up to 1 Gbs. Some journalists mistakenly though this meant BPL could realistically reach such speeds in the real world, even stating that BPL could have an edge over cable or DSL. However, the conditions in the Penn State study were anything but real world and today I'm unaware of anyone who has publicly demonstrated 1 Gbs BPL in the field or in a lab. A Penn State researcher did state that he did not expect BPL to reach speeds of 1 Gbs in the real world, but that speeds of 500 Mbs may be achievable. Comparing this to cable, cable has a raw bandwidth of about 1 Ghz, and assuming a 5 bit/hertz modulation efficiency it could achieve speeds of 5 Gbs. If comparing apples to apples, the perfect world conditions found in the Penn State study when applied to cable would likely produce tens of gigabits of top bandwidth for cable and several gigabits for DSL.



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Q: What companies are offering Internet access BPL system equipment?

A:

Vendor

Modulation / Standard

Special Features

System Bandwidth (not Individual Subscriber)

Comments

Ambient

OFDM (DS2 Chipset)




Amperion

OFDM (DS2 Chipset)

Uses 802.11b wireless from pole to home

Up to 20 Mbps depending on line quality and equipment spacing

Uses 4.5 Mhz wide downstream channels and 3.5 Mhz wide upstream

Ascom

GMSK


4.5 Mbps

Uses 1.6-12 Mhz spectrum

Acquired by Current Technologies in March 2006

Corinex





Current Technologies

Homeplug



Reported to use frequencies above 30 Mhz more often than HF. Has largest system in US with no open interference complaints.

Gridstream

Homeplug


2 to 22 Mbps


IBEC

Homeplug




Ilevo

OFDM (DS2 Chipset)



No known registered systems in US

Main.net

Spread Spectrum



Found to be using 1.6 to 30 Mhz in the field

Motorola

Homeplug

Uses Canopy unlicensed 5.2/5.8 GHz UNII band wireless for backhaul and BPL only on LV lines into home


Only system known to use wireless for the backbone.

Test system is in operation at ARRL Headquarters.

Mitsubishi

Homeplug (Yitran Chipset)




PowerWAN

Proprietary OFDM

Hybrid fiber system

14 Mbps physical, 6 to 8 Mbps usable

No known registered systems in US.



Q: Are any BPL systems better at preventing interference?

A: Motorola's system doesn't use BPL on medium voltage overhead lines, but instead uses 802.11 wireless between nodes. The path from a node into the home is via BPL over low voltage lines (120/220VAC). The lines into homes in the US are usually twisted (much like copper pairs used by phone lines, T1s, and DSL) and are much better suited for higher bandwidths. Motorola also included component based filters to filter out Amateur Radio band frequencies from their system. Most if not all manufacturers use digital signal processing filters which are based in software and not nearly as effective. It should be noted that the ARRL has a live Motorola BPL system operating at their Newington, CT headquarters. The system hasn't interfered with receivers, nor has the BPL system suffered from ingress interference from ARRL's several 1.5 kW transmitters operating simultaneously on site.

Current Technologies uses a Homeplug based system which notches out Amateur Radio spectrum by default, and Current is rumored to use VHF (30 – 80 Mhz) spectrum almost exclusively. Current operates what is believed to be the largest commercial system in the US in Cincinnati, OH with no open interference complaints at the time of this writing.



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Q: Couldn't Hams use power lines as antennas?

A: Technically anyone can as long as they operate under Part 15 rules. This concept is called Carrier Current and is used by some unlicensed (legal) AM broadcasters. This is done by injecting very low power radio frequencies into the line. The difference between classic Carrier Current and BPL is that Carrier Current uses one distinct frequency, typically a standard AM channel. BPL is wide band in nature and uses several megahertz. Note that the entire reason someone would use Carrier Current is that the power lines radiate the signal, acting like a distributed antenna – something many BPL proponents claim just doesn't happen. If Hams used power lines as antennas with typical Amateur power levels, the results would be disastrous with massive interference to many residential devices.

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Q: Will BPL radio energy on power lines be detrimental to people?

A: No, the low power levels that BPL uses will not have detrimental biological effects.

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Q: Do Hams oppose broadband deployment?

A: Hams are people like you. Hams want broadband just as much as anyone else and the same percentage of Hams as the general population are dealing with the same lack of broadband Internet. You don't see Hams standing up and blocking cable or DSL deployment, so to say that this is entirely a movement of people who don't care about “broadband challenged” citizens is just plain wrong and perhaps one of the stupidest arguments I've heard to date. The movement against BPL is strictly technology based.

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Q: Hasn't the FCC approved BPL? / What changes were made in BPL regulations as a result of FCC Rulemaking 04-37?

A: This is often seen in forums, and the FCC has always been bullish on BPL, however the FCC never “approved” BPL in the strictest sense of the word. They released a rule making which enacted new regulations meant to encourage BPL deployment, however BPL has technically always been permitted under Part 15 rules. The new rules enacted several restrictions or clarifications including:

If one takes the viewpoint that the FCC didn't ban BPL in the rule making, so it's an approval, that's one opinion. However, after publication of the new rules, BPL has additional encumberments that were not there previously.

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Q: Do the new FCC Rules require testing of BPL devices?

A: Yes, after an 18-month grandfathering period, the FCC will require that access BPL that uses overhead medium voltage lines be certificated as described in Part 15 rules. The following general conditions apply:



For overhead lines, BPL at HF frequencies (1 - 30 MHz):

or alternately:

For overhead lines, BPL at VHF frequencies (30 – 80 Mhz):

In-house BPL or BPL not using overhead wiring does not have to be certificated, but can continue to be verified (completely self tested) as described by the FCC's rules.

The manufacturers will also have a requirement to make these measurements in three typical systems, with the data rates and usage and power levels set to their maximum levels. The test results are submitted to the FCC, who then issue the certification based on those test results. After the certification is issued, individual installations do not have to be tested.

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Q: Won't BPL be different than Cable and DSL and deliver broadband to those who don't have it, especially in rural areas?

A: If you don't have broadband now, there's probably one good reason – lack of sufficient revenue in your area. People are mistaken in thinking that BPL providers are going to go out of their way to deliver BPL to country folk, as if this is some kind of humanitarian effort to get the country on the 'net. It's not. Companies are in business to make a profit, plain and simple. Being a good corporate citizen in a community makes great press releases, but such efforts stop when the bottom line is affected.

Let's talk about the differences and similarities between Cable, DSL, and BPL for a moment. Cable requires a unit at the origination of the cable system, also known as a headend. This unit is expensive, but can service hundreds to thousands of customers. The cable system is already built with repeaters for the video part of the system called amplifiers. So the major investment for cable is at the headend, and service can be delivered basically anywhere cable already is deployed. The upstream Internet network must be brought to a single point, the cable headend.

DSL is based out of telephone central offices using a device or peripheral called a DSLAM. Like a cable modem headend unit, it can provide service to hundreds of customers. DSL service can be provided about 18,000 feet from the DSLAM. This has severely limited DSL deployment. As with cable, the upstream Internet network must be brought to a single point, the central office. Any ILEC or CLEC probably already has significant Internet bandwidth available at any central office serving business customers.

BPL service is provided by a DSLAM/Cable headend type device, but its effective distance is 200 meters or 656 feet. Every 200 meters a repeater must be used to regenerate the signal. BPL service can't really be distributed from a central point like Cable or DSL, so the upstream Internet network must be backhauled to each BPL feed point via telco facilities such as fiber or copper.

So to deploy BPL an up front investment must be made in BPL headend/feed point equipment and repeaters. There's going to be significant recurring costs in backhauling the IP traffic from the numerous BPL feedpoints serving an area. Neither DSL or Cable has this recurring cost or need for multiple network origination points. These costs unique to BPL make it even less attractive for deployment in rural areas that Cable or DSL as customer densities and revenue potential is lower. While it may be stated by BPL providers that initial metropolitan buildouts are needed to subsidize rural deployments, why would any for-profit company expand into rural areas when it's a losing proposition?

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Q: Why don't the utilities just bury all the power lines to lessen interference?

A: If digging up the entire country for power line burial would be an option, it would make better sense to just run buried fiber everywhere. Fiber has so much, much more bandwidth compared to BPL it would be frivolous to go through such a drastic project just to bury cabling that can ideally carry only 100 kHz of bandwidth.

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Q: Don't other consumer electronics equipment like plasma TVs, electric blankets, garage door openers, baby monitors, etc. cause interference?

A: Yes, they often do, but none of these are miles long, 30 feet in the air, on for 24 hours a day, or occupy tens of megahertz of spectrum simultaneously like BPL. FCC Part 15 was designed to allow devices like these and others to cause a little localized interference and not require overly expensive construction to be completely clean. BPL uses Part 15 in a way it was never intended.

Q: Shouldn't Hams be responsible for coming up with an alternate broadband solution?

A: Hams are merely the messengers. A good analogy is that they are the “canaries in the coal mine”.  Hams cannot use their spectrum for commercial purposes, so designing an alternate over-the-air technology using ham frequencies is out of the question. The responsibility of providing a broadband solution over power lines or other mediums is not their responsibility as some have suggested. BPL is a technology created by commercial interests with profits in mind.

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Q: Why don't Hams work to help solve the problems of BPL they claim exist?

A: At the time of this writing, the ARRL is assisting several BPL manufacturers at various levels. ARRL and individual amateurs have volunteered to help utilities and BPL manufacturers make measurements or assess interference to and from BPL.

ARRL Workiing with BPL Chip Manfacturer DS2

ARRL Working With / Testing Motorola BPL Technology

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Q: Do amateurs  wish to stop BPL?

A: The issue is with the interference generated with BPL, not BPL itself or broadband. If someone came up with truly interference-free BPL, amateurs and their organizations would not oppose it, and may even support it.

Q: Can/have ham radio transmissions interfere/interfered with BPL systems?

A: Yes. Tests have shown that some systems are vulnerable to as little as five watts of radio frequency energy. Most ham radio stations use 100 watts of power, some use as much as 1500 watts. Interference from outside wireless services into a BPL system is sometimes referred to as ingress interference.

Q: Should/will Amateur Radio Operators interfere with BPL systems?

A: I personally do not encourage deliberate interference from Amateurs to BPL systems. It does not put Amateurs in a good light and doesn't win public support. Unintentional ingress interference will naturally occur due to the construction of power lines and the areas that BPL equipped powerlines typically cover (streets in suburban areas.)

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Q: What are your qualifications?

A: I currently work at a broadband licensed wireless carrier. I have experience in RF engineering in HF, VHF, UHF and microwave frequencies. I've deployed unlicensed Part 15 wireless Internet services and I'm an avid Amateur Radio operator who builds equipment and enjoys QRP (low power) operation and CW (morse code) as well as several digital modes. I am President of a local Amateur Radio organization and a member of the American Radio Relay League.

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Q: Can people subscribe to BPL Internet service today?

A: In several areas, yes. Check with your local utility.

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Q: Where can I get other BPL information?

A:

Carriers

 

Central Virgina Electric Cooperative

 

Cinergy Corp

 

City Of Manassas

 

 

Equipment Vendors

 

Amperion

 

Ambient

 

Current Technologies

 

Main.net

 

 

BPL Advocacy

 

APPA

 

PLC Forum

 

PLCA

 

UPLC


BPL Today

 

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Q: Is there some wrong anti-BPL interference information being disseminated?

A: As with any issue on the Internet, misinformation or misinterpretations can occur. Some wrong information I've seen:

·       BPL Power Levels: BPL does not uses watts or kilowatts of power.

·       BPL Outlawed in Europe: No, it was never outlawed there, although it was outlawed in Japan for some time.

·       BPL Biological Effects: There is no risk of direct biological damage from BPL.

·       BPL Security Issues: BPL signals can be intercepted over the air but are undoubtedly encrypted and difficult to decode or do “man in the middle” network based attacks. A particular vendor may have packet sniffing vulnerabilities, however there is not an across-the-board issue with all BPL vendors due to the radiation and interference issue, in my opinion.

·       BPL Affecting Domestic (VHF) Aviation Frequencies: BPL does affect transoceanic/international aviation frequencies but not VHF frequencies commonly used at airports for navigation, landing and takeoff, etc. at 108 to 136 Mhz.

Here is a listing of international aviation bands that are potentially affected by BPL:


kHz


2850-3155


3400-3500


4650-4750


5450 5730


8815-9040


10005-10100


11175-11400


13200-13360


15010-15100


17900-18030


20005-21000


21850-22000


21964


22720-23200


23200-23350


23350-24890

 

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Q: How many people subscribe to BPL?

A: The FCC released a report in late 2005 that listed 4,872 subscribers in the “Power Line and Other” category. Cable had rough 23.9 million subscriber, DSL had 16.1 million. BPL had a 0.011 % market share of all broadband technologies.

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Q: Where is BPL currently operating in the United States?

A: The ARRL has an extensive BPL database located here . The UPLC maintains the BPL industry database required by 47 CFR 15.615 at www.bpldatabase.org .



Q: Have any BPL sites been deactivated?

A: These sites were deactivated due to interference issues or an involved party decided to scrub the project:

State/ Province

City

Carrier

Equipment

Reason Cited by Carrier

Unresolved Interference Claims

Comments

California

Menlo Park

PG&E

Main.net

Business

No

AT&T Involved

Iowa

Cedar Rapids

Alliant Energy

Amperion

Interference

Yes


New York

Penn Yan

City of Penn Yan

Amperion

?

Yes

Abandoned, migrating to wireless

North Carolina

Raleigh

Progress Energy


Pilot project was successfully completed

Yes


Pennsylvania

Allentown / Bethlehem / Emmaus

PPL

Amperion, Main.net

Couldn't make business model work

Unknown

5 Sites

Texas

Irving

TXU Electric

Amperion

Pilot project was completed

Yes

More Information: NTX BPL Team

Deactivated 3/2005

Unresolved Interference Issues

Various

Various

IDACOMM

Amperion, Main.net, Ambient

Decided to exit business due to lack of utility interest

Unknown


Maryland


SMECO

Current

"BPL signal speeds and bandwidth are not competitive with other technologies currently available."

No


Arizona

Cottonwood

Arizona Public Service / Mountain Telecommunications Inc

Mitsubishi

No public reason cited

Yes

Equipment reported to be deinstalled





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Q: Are BPL carriers required to give the public information about their systems?

A: Yes. Title 47 Part 15.615 (a)-(e) requires carriers to register their systems in a public database. This database is currently administrated by UTC / UPLC and is located here . Despite system registration being required by law, at the time of this writing several companies operating BPL systems have failed to register their systems.

Q: Can I email you a question?

A: Yes, I can be reached at goody at qrpis dot org. I will be happy to answer any question you may have and if I don't have the answer, I'll research it.

I will ignore insulting emails. If you're going to suggest corrections, please be able to support your corrections with specific technical information. I find BPL sales and marketing drones annoying and I don't get information from pamphlets or sales glossies. I occasionally get terse little emails saying that my FAQ is wrong or has misinformation, yet the writer won't cite anything specific or if they do cite something they don't back it up with any facts. Please don't waste my time or yours with wasteful emails like this.

Any emails sent to me become my property and questions or content may be posted here or elsewhere. If you have information that you would not like posted verbatim here, I will consider signing an NDA.

 Acknowledgments

Thanks to Art, KC2G, for proofreading my work. Thanks to Gary, N0JCG, for contributing information on G-line. Thanks to countless others who have posted information in public forums or anonymously contributed information for this FAQ, and those who have asked questions that eventually ended up in the FAQ.

The information provided above is believed to be accurate, however no warranty for any use is stated or implied. All copyrights and trademarks are property of their respective owners.