Power Line Communications
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The use of the electrical power lines to carry high speed data poses a possible threat to HF amateur radio, because the digital signals carried by the power lines may interfere with radio reception in the amateur bands. The converse is also true. Amateur radio signals may be picked up by the power lines, and block the transmission of the digital data.
Power lines have traditionally been used to carry low speed data in the lf and vlf range, where radiation is much less likely to happen. The term used for these traditional systems is Power Line Communications (PLC) or Power Line Telecommunications (PLT). In Europe, the term PLC is also used for the Broadband data transmission, whereas in North America, the term Broadband over Power Lines (BPL) is more commonly used.
This page will provide information on the development and implementation of this technology in Canada.
Amperion is the company who manufactures the BPL equipment being tested at Sault Ste Marie. To see some of their press releases, click here. Amperion - Press
IARU Region 1 struggling against BPL - 2004-06-19
The struggle for the protection of the radio spectrum against intolerable interference levels generated by Powerline Telecommunication (PLC) techniques has gone on for several years. Here is a summary of recent activities in Europe.
January 2003, the European Commission convened a "Stakeholders" meeting on PLC. It was decided to widen the scope of Mandate 313 from the EU Commission charging CENELEC/ETSI with developing standards for digital telecommunications over wired networks.
April 2003, a meeting was convened by the World Broadcast of Radio Nederland in Hilversum. Mark Bogers, EC Directorate Industry, accepted to meet a group of HF users to discuss the PLC issue. The meeting was reported in the EUROCOM Newsletter of 30.04.2003. It became clear that the EU would promote large scale PLC trials.
At Ham Radio, Friedrichshafen 2003, the EMC and EUROCOM working groups set up a joint meeting. Moreover, a PLC Information Stand provided information on the PLC issue to the visitors of Ham Radio. In 2003, at European Union level, the main action has been led by the IARU delegates to ETSI, more precisely by their participation to the meetings of the CENELEC/ETSI Joint Working Group. This work has been monitored by the EMC working group.
July 2003, the EUROCOM WG chairman received a letter from the EU Commission calling for comments on the PLC issue. The comments would be summarised and submitted to a restricted PLC Workshop. Hilary Claytonsmith, G4JKS accepted to prepare a contribution on behalf of IARU Region 1. The EU PLC Workshop was convened October 2003 and restricted to Member States representatives. Mandate 313 was extended to allow more time to the JWG.
February 2004, as the result of another EU Workshop on PLC, the EU Commission decided to prepare a Commission Recommendation, based on a Technical Specification for electromagnetic emissions from access powerline communications networks. This Technical Recommendation has been prepared by the CENELEC/ETSI JWG and submitted to the Member States. A voting on three options of permitted interference levels is awaited May 15th, 2004.
(Thanks to Gaston Bertels, ON4WF in the IARU EUROCOM Newsletter)
RTA and DARC e.V. present this document as a contribution to inform the amateur radio community on the issue of BPL and as discussion material to be used in public relations efforts. Latest developments are taken into account.
The paper is a common effort of DF7VX, DJ6AN, DJ1ZB, Mrs. Volmer, DL2CH, DJ8CY, DF5DP, DF4JI, DL9MH and DF9IC and of the member societies of the RTA.
Translation by ON4WF.
BPL not recommended
1. BPL - How it works
BPL (PLT) is the acronym for Power Line (Tele) Communication. Intended is to implement telephony and high rate Internet data transmission on the existing 230 V (50 Hz) power grid in the users home, as well as Data, Audio and Video transmission from outlet to outlet inside a building or dwelling place (domestics). The data transmission that occurs broadband on radio frequencies up to 30 MHz. Not intended for the transmission of radio waves on frequencies up to 30 MHz, the mains act as radiating antennas. BPL operators are (or will be) subject to radiation limits. Legal reference is the not yet enforced NB 30 frequency management norm. Most BPL systems will not be up to these constraints and consequently exceed the limits.
It has to be noted, that several existing appliances such as baby phones, garage door openers and heating controls are also mains channeled BPL applications. Using very low frequencies instead of high frequencies, these applications are free from under mentioned shortcomings and appropriate for domestic use.
2. BPL disturbs short wave radio services
BPL short wave frequencies have since long been allocated to various radio services such as broadcasting, air and maritime communications, fixed and mobile radio services, military, security services, radio astronomy, etc. not to forget the amateur radio service. Even with radiation limited to the NB30 norm, short wave reception is considerably disturbed because the receiving antennas cannot be set up far enough from the mains. Medium waves broadcasting and other frequencies can also be disturbed. These disturbances can endanger the very existence of some radio services, such as short wave broadcasting and the worldwide amateur radio service.
3. Short wave radio disturbs BPL
Widely distributed power lines, acting as antennas, not only produce strong disturbing radiation but also collect all kinds of high frequency signals, resulting in high noise levels on the mains. Regulations provide no legal protection of BPL against disturbances. High noise levels can considerably lower the data rate and even disrupt transmission, preventing the service provider to furnish the granted data rate. BPL's immunity from disturbances is determined by the degree of protection built in the system itself. High immunity calls for a corresponding degree of protection measures, detrimental to the effective transmission capacity (data rate).
4. BPL can disturb other electronic devices
Since BPL signals, traveling on the power mains (230V - 50 Hz), directly access all mains fed devices, it is likely that a multitude of electronic devices will suffer interference, in particular entertainment and medical equipment in hospitals and consulting rooms. Most such devices have no special protection against BPL signals and are exposed to disturbance. In critical locations, such as intensive care services, human lives can be endangered. For safety's sake, each device will then need appropriate and expensive protection measures.
5. BPL is unsure
A paper on BPL, published by the society for science and technology of the Dresden Technical University, concludes that BPL efficiency suffers from the mains “impedance instability” resulting from totally uncontrollable consumer on- and off-switching.
6. Right now, BPL is an outdated system
Electronic devices and modulation systems used for BPL draw on the latest technical developments in order to assure proper data transmission on since long heavily polluted power wires. Compared to alternative techniques, the BPL data transmission system, with a data rate limited to some 2 MB/second, does not even match ADSL (data transmission on telephone wires at 8 MB/second) commonly presented to the public. Amateur radio operators consider cable TV data transmission a valuable alternative. ADSL also, provided that nearby amateur radio frequencies be protected by adequate filtering. These amateur radio reserves do not in any case extend to future alternative solutions such as fiberglass cable, microwave systems for small cells or the oncoming UMTS mobile system.
7. BPL is exposed to eavesdropping and malicious jamming
Like all radio signals, BPL can be intercepted and copied by anybody in the home or building. Therefore, providers will take steps to secure BPL transmissions. Protection efficiency will depend upon securing measures, which ordinary end users cannot control. Users have no means to evaluate risks and cannot decide when to protect themselves. Since no connection is needed, eavesdropping is easy. Considering the expected numbers of users, illegal copying will rise to unheard of summits, and the foreseeable lack of data security is extremely high. Since radio transmissions are exposed to interference, a user terminal can easily be disturbed by a nearby jammer, even with low power.
8. BPL interference breaks the freedom of information
BPL can totally disrupt short wave broadcast reception cherished by our foreign fellow-citizens, as well as medium wave broadcasting and other radio services, such as the international Amateur Radio service. This is an infringement of Article 10 of the European Convention on Human Rights (fundamental right to active and passive freedom of information) since access to not otherwise accessible information is denied. On the other hand, practically all information and services offered by BPL are accessible through other and at least equally valuable or better techniques.
9. BPL raises completely new legal issues
Problems related to the delivery of data by power companies to end users at the limit of the property or at the power outlet in house (as well as the technical and legal liability for the BPL connection and for the content of the BPL exchange), refusal of citizens to accept the presence of BPL data on their property, endangered freedom of information and lack of data safety as well as questions about the applicable legislation on electromagnetic compatibility (EMC) in case of interference, raise legal issues and endanger good neighborhood.
10. BPL is not economically justified
Compared to other data transmission systems, BPL is a waste of economical resources. In the United Kingdom, the promoters of BPL withdraw soon after some initial enthusiasm. Taking into account the cost and the return ratio of BPL, it is foreseeable that market mechanisms, once coverage becomes widespread, will confirm likely negative results. The limited range of BPL restricts the implementation to densely populated areas, where a multitude of users has to share a limited bandwidth.
11. BPL's efficiency does not meet the growing need of quick data transmission
In distributed workplaces, professional computers nowadays show data transmission rates of 100 Mbit/s. Industry prepares a norm based on 10 Gbit/s. Professionals agree that datatransmission to PC terminals follows the law of Moore, stating a two-fold increase of processing speed every 15 to 18 months. Personal computers of individual users will benefit of this technical development. Evidently, the projected BPL data rates of some two Ambit/s from provider to user will be outdated once widely spread. Shareholders of BPL promoting concerns should be aware of this when making decisions on the stock exchange.
Opponents expressed their concern in a public hearing on frequency management presented by the German regulatory authority, more precisely about the norm NB 30. Significant is the negative position taken up by representatives of safety services, military, broadcasting, internationally renown manufacturers of short wave equipment and audio and HF measuring instruments, other radio services and short wave users such as radio astronomy.
13. Their experimental service threatened to death, the radio amateurs strongly oppose BPL
Using very sensitive receivers for their experimental service, radio amateurs are especially concerned. In an official hearing of the German ministry of trade, they firmly expressed their opposition to BPL. Amateur radio operators have observed pilot projects, measured and made available the interfering signals. The DARC has participated as observer to tests performed by the spectrum surveillance service. Radio amateurs have taken part in press conferences of future BPL providers and their questions have given rise to considerable uncertainty. Radio amateurs, primarily concerned, have produced press releases against BPL, participated to TV programmers, given interviews to local newspapers and alerted the European and the German members of Parliament. The DARC has exposed the issue to EUROCOM (European Union workgroup of the International Amateur Radio Union) as well as to the IARU conference and to the radio amateur community throughout Europe and worldwide. Common action of European amateur radio societies has been developed. Outside of Europe, progress was noted in New Zeeland and in Australia where radio amateurs showed considerable awareness and concern about these critical developments.
Karl Erhard Vögele, DK9HU
Canadian radio amateurs using the high frequency and VHF spectrum are becoming concerned that proposed broadband over power line (BPL) systems may render the bands unusable due to radiation from the power lines. Broadcasters and government agencies also fear that BPL radiation, including harmonics, have the potential to cause interference to VHF TV, FM radio and military and public safety communications in the HF and lower VHF spectrum.
Six weeks or so ago, I read a story that a California company, Corridor Systems, has demonstrated a BPL system that works at 2.4 and 5.3 GHz. The system, is designed to provide broadband (250 MHz) transmission suitable for high speed Internet access, using the existing power distribution system, but which does not pose any threat whatever to amateur radio or other users of the rf spectrum.
I tracked down Corridor Systems Chief Technology Officer, a radio amateur, Glenn Elmore N6GN, and he assured me that their BPL technology would not interfere with the HF ham bands. The story below is based on information found on the Corridor Systems web site.
Corridor Systems has developed and patented core technology that enables very high capacity, symmetric and full-duplex information transport over a variety of propagation medium types. Power Corridortm is an implementation of this fundamental technology which operates, in part, over a single conductor of an unmodified, existing power line. In Power Corridor&tm; , information-carrying energy is coupled on and off the conductor by identical launch devices at each end of conductor segments. This energy, which may extend from VHF through the microwave portions of the spectrum, is launched as a surfacewave mode around the conductor.
Surfacewave transmission on an insulated single conductor was first discovered and presented by Goubau1 in the early 1950's and known as G-Line2 after the inventor. The characteristics of surfacewave propagation, when used with a variety of dielectric types, thickness and specially prepared conductors, have been taught and available in reference texts for many years3. Though not widely utilized in practice, the mode can exhibit extremely low radiation and transmission losses from VHF into the microwave regions.
Corridor Systems has discovered, extended, developed and patented a much more general surfacewave mode for operation on lines which may be completely uninsulated and which need not have any special surface preparation. Additionally, lines which are much larger in diameter than those of previous work may be utilized. This invention, which makes possible very high rate information transport over existing medium-voltage electric utility power lines, is called E-line&tm;. As with G-line, the vast majority of energy propagates within a volume located relatively close to the single conductor. In Power Corridortm the diameter of this volume is only a few inches. Since the energy propagates at very nearly the speed of light, the relative velocity of propagation in this mode is quite close to unity.
Combined with the normal clearances maintained for aerial medium and high-voltage power lines and Corridor System's specially developed and patented launching devices, E-linetm provides an extremely effective mechanism for the transport of very high speed information over existing power line grids.
Measurements at ground level directly under the power line used during the test showed a maximum radiated power level of less than -10 dBm, 20 dB less than the typical power level from 802.11 based wireless cards.
Corridor Systems has tested and demonstrated simultaneous operation of its BPL technology and amateur radio HF communications. Utilizing a 100 watt, 7 MHz, 21 MHz and 28 MHz amateur SSB/CW transmitter connected to a dipole antenna located within 20 feet of an operating BPL system, there was not any evidence whatsoever of the operation of one system in the other. Amateur UHF communications at 446 MHz and at a 25-watt power level were similarly unaffected and in turn were not detected by the BPL system. Examination of the .1-30 MHz HF spectrum with a quality communications receiver also revealed no evidence of the BPL system.
Glenn also told me that Corridor's demonstration not only used the unlicensed bands, FCC Part 15 in the US, but also simultaneously supported fast scan amateur television with stereo audio under Part 97 of the US Rules. So while the system was being used to support high speed internet traffic it also served as an “open band” for amateur radio uses-- even with one end of the TV link mobile on the roadway near the power lines!
More information and photos can be found at: