Frequently Asked Questions About PBL
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Q - What is BPL, and why is it a possible threat to Amateur Radio?
A - BPL systems transmit high frequency digital data over existing electricity distribution wiring. Because the wires are usually not shielded, and are widely spaced, the signals may be radiated, or coupled from the electric wires into amateur receiving antennas causing interference - most often in the HF bands between 80 and 10 metres.
Q - What is "Access BLP"?
A - BPL can use your internal house wiring to link computers together, or to couple other devices to computers.
BPL can also be used on outdoor power lines to connect users to the Internet. This application is often referred to as "Access BPL".
Q - What is RAC doing about BPL?
A - RAC has bee discussing BPL technology with the responsible people at Industry Canad since the first experimental systems appeared in Europe about 5 year ago. We have also been in close communication with those concerned abou BPL in other amateur societies, particularly the ARRL.
We have regularly provided Industry Canada with information on BPL developments around the world, and informed them about our serious concerns that BPL may interfere with amateur operations in HF and VHF amateur bands.
We have also warned Industry Canada, that amateur stations operating in accordance with Canadian regulations, may interfere with BPL signals on the power lines.
We have discussed BPL with other HF spectrum users in international meetings, and in the Radio Advisory Board of Canada, and again raised our concerns.
And finally, through the IARU, we are attending ITU meetings and participating in studies of possible increases to the noise floor world-wide due to ionospheric propagation of radiated BPL signals.
Q - Which amateur bands may be interfered with by BPL signals?
A - Most systems currently being tested, use the frequency range from about 3 to 30 MHz for their signals. Some companies are considering extending the bandwidth to as high as 80 MHz to allow increased data rates.
Q - Is there a difference between the BPL proposed in North America, and that currently implemented in some European countries?
A - Yes, the physical layout of North American power distribution is much different from that used in Europe, and in most cases our wire spacing is greater, leading to a higher potential for interference here.
Q - Can a BPL system operate without Industry Canada authorization?
A - Any wire communications system which does not intentionally radiate RF signals, does not require Industry Canada approval to operate, if it does not produce interference to radio services.
However, many non-intentional radiators do generate RF interference, and Industry Canada publishes standards for some types of equipment, defining acceptable emission levels. These documents are called ICES (Interference Causing Equipment Standards), and may be downloaded from the Industry Canada web site at:
Q - Have any operational BPL systems been authorized by Industry Canada?
A - As mentioned in the above question, wire communications systems are not subject to Industry Canada authorization. However, there are several experimental trials currently undertaken by Power Utilities that are being monitored by Industry Canada with a view to determine next steps.
Industry Canada is aware that BPL has the potential to cause interference to existing users of radio frequencies in services such as Aeronautical mobile, Aeronautical radionavigation, Amateur, and Broadcasting amongst others. As this is a new technology, they are interested in those trials where the benefits of the technology as well as any possible adverse affects it may have on radio frequency users may be evaluated. RAC has been assured by Industry Canada that, in determining next steps, they will ensure consultation among all involved stakeholders before moving ahead.
Q - Has Industry Canada issued an ICES document specifically for BPL systems?
A - No, at the present time, only low frequency carrier current systems are subject to an ICES standard.
ICES-006-AC Wire Carrier Current Devices (Unintentional Radiators) can be downloaded from the IC web site. This Interference-Causing Equipment Standard sets out limits and method of measurement of radio noise emissions and specifies maximum permissible output voltages from AC wire carrier current devices of a design for which any radiation of radio frequency energy is unintentional.
According to ICES-006, "Subject to further study by Industry Canada on cumulative effects of multiple devices:
Q - Has Industry Canada established emission limits for BPL in Canada?
A - As of April 2004, Industry Canada has not yet decided on acceptable emission limits for BPL systems in Canada. They monitoring international activities related to BPL, particularly in the USA in order to determine the next step.
Q - What will my receiver S-Meter read if the interference level is 30 microvolts/meter?
A - That will depend on the nature of the interference, your antenna gain, your IF bandwidth setting, and the frequency of course. A source of interference, 30 metres from a half wave dipole at 7 MHz, is in the near field of the antenna, and the received signal is difficult to calculate.
Very approximately, a broad band interfering signal of 30 microvolts/meter at 30 meters from a half wave dipole at 7 MHz is equivalent to about an S-8 SSB signal, or an S-6 CW signal.
Q - Is anyone studying the possibility that BPL systems may radiate enough energy to propagate long distances via the ionosphere, and raise the HF noise floor in countries far removed from the system?
A - Yes, a number of studies are taking place around the world, for example both the ITU and NATO are currently beginning studies of this potential problem. The BBC has conducted its own internal engineering study, and published the results.
Q - Is there more than one type of BPL system on the market?
A - Yes, there are a number of competing technologies, some of which may cause more interference than others. This variety of systems further adds to the complexity of the interference problem.
Q - Has anyone disagreed with the FCC proposals to set an emission control limit for BPL in the USA?
A - Yes, there have been many responses, to see what some of the respondents have said, download the following file - in pdf format (about 100Kbytes).
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