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Power Line Communications |
| Canada's National Amateur Radio = Society | |
| "We're ALL about Amateur Radio!" "Tous = ensemble pour=20 la radioamateur!" |
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The use of the electrical power lines to carry high speed data = poses a=20 possible threat to HF amateur radio, because the digital signals = carried=20 by the power lines may interfere with radio reception in the = amateur=20 bands. The converse is also true. Amateur radio signals may be = picked up=20 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=20 lf and vlf range, where radiation is much less likely to happen. = The term=20 used for these traditional systems is Power Line Communications = (PLC) or=20 Power Line Telecommunications (PLT). In Europe, the term PLC is = also used=20 for the Broadband data transmission, whereas in North America, the = term=20 Broadband over Power Lines (BPL) is more commonly used. This page will provide information on the development and=20 implementation of this technology in Canada.
Amperion web = siteAmperion is the company who manufactures the BPL equipment =
being tested=20
at Sault Ste Marie. To see some of their press releases, click =
here. BPL in = EuropeIARU Region 1 struggling against BPL - = 2004-06-19The struggle for the protection of the radio spectrum against=20 intolerable interference levels generated by Powerline = Telecommunication=20 (PLC) techniques has gone on for several years. Here is a summary = of=20 recent activities in Europe. January 2003, the European Commission convened a "Stakeholders" = meeting=20 on PLC. It was decided to widen the scope of Mandate 313 from the = EU=20 Commission charging CENELEC/ETSI with developing standards for = digital=20 telecommunications over wired networks. April 2003, a meeting was convened by the World Broadcast of = Radio=20 Nederland in Hilversum. Mark Bogers, EC Directorate Industry, = accepted to=20 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=20 EU would promote large scale PLC trials. At Ham Radio, Friedrichshafen 2003, the EMC and EUROCOM working = groups=20 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=20 European Union level, the main action has been led by the IARU = delegates=20 to ETSI, more precisely by their participation to the meetings of = the=20 CENELEC/ETSI Joint Working Group. This work has been monitored by = the EMC=20 working group. July 2003, the EUROCOM WG chairman received a letter from the = EU=20 Commission calling for comments on the PLC issue. The comments = would be=20 summarised and submitted to a restricted PLC Workshop. Hilary=20 Claytonsmith, G4JKS accepted to prepare a contribution on behalf = of IARU=20 Region 1. The EU PLC Workshop was convened October 2003 and = restricted to=20 Member States representatives. Mandate 313 was extended to allow = more time=20 to the JWG. February 2004, as the result of another EU Workshop on PLC, the =
EU=20
Commission decided to prepare a Commission Recommendation, based =
on a=20
Technical Specification for electromagnetic emissions from access=20
powerline communications networks. This Technical Recommendation =
has been=20
prepared by the CENELEC/ETSI JWG and submitted to the Member =
States. A=20
voting on three options of permitted interference levels is =
awaited May=20
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=20 amateur radio community on the issue of BPL and as discussion = material to=20 be used in public relations efforts. Latest developments are taken = into=20 account. The paper is a common effort of DF7VX, DJ6AN, DJ1ZB, Mrs. = Volmer,=20 DL2CH, DJ8CY, DF5DP, DF4JI, DL9MH and DF9IC and of the member = societies of=20 the RTA. Translation by ON4WF. BPL not recommended1. BPL - How it worksBPL (PLT) is the acronym for Power Line (Tele) Communication. = Intended=20 is to implement telephony and high rate Internet data transmission = on the=20 existing 230 V (50 Hz) power grid in the users home, as well as = Data,=20 Audio and Video transmission from outlet to outlet inside a = building or=20 dwelling place (domestics). The data transmission that occurs = broadband on=20 radio frequencies up to 30 MHz. Not intended for the transmission = of radio=20 waves on frequencies up to 30 MHz, the mains act as radiating = antennas.=20 BPL operators are (or will be) subject to radiation limits. Legal=20 reference is the not yet enforced NB 30 frequency management norm. = Most=20 BPL systems will not be up to these constraints and consequently = exceed=20 the limits. It has to be noted, that several existing appliances such as = baby=20 phones, garage door openers and heating controls are also mains = channeled=20 BPL applications. Using very low frequencies instead of high = frequencies,=20 these applications are free from under mentioned shortcomings and=20 appropriate for domestic use. 2. BPL disturbs short wave radio servicesBPL short wave frequencies have since long been allocated to = various=20 radio services such as broadcasting, air and maritime = communications,=20 fixed and mobile radio services, military, security services, = radio=20 astronomy, etc. not to forget the amateur radio service. Even with = radiation limited to the NB30 norm, short wave reception is = considerably=20 disturbed because the receiving antennas cannot be set up far = enough from=20 the mains. Medium waves broadcasting and other frequencies can = also be=20 disturbed. These disturbances can endanger the very existence of = some=20 radio services, such as short wave broadcasting and the worldwide = amateur=20 radio service. 3. Short wave radio disturbs BPLWidely distributed power lines, acting as antennas, not only = produce=20 strong disturbing radiation but also collect all kinds of high = frequency=20 signals, resulting in high noise levels on the mains. Regulations = provide=20 no legal protection of BPL against disturbances. High noise levels = can=20 considerably lower the data rate and even disrupt transmission, = preventing=20 the service provider to furnish the granted data rate. BPL's = immunity from=20 disturbances is determined by the degree of protection built in = the system=20 itself. High immunity calls for a corresponding degree of = protection=20 measures, detrimental to the effective transmission capacity (data = rate). 4. BPL can disturb other electronic = devicesSince BPL signals, traveling on the power mains (230V - 50 Hz), = directly access all mains fed devices, it is likely that a = multitude of=20 electronic devices will suffer interference, in particular = entertainment=20 and medical equipment in hospitals and consulting rooms. Most such = devices=20 have no special protection against BPL signals and are exposed to=20 disturbance. In critical locations, such as intensive care = services, human=20 lives can be endangered. For safety's sake, each device will then = need=20 appropriate and expensive protection measures. 5. BPL is unsureA paper on BPL, published by the society for science and = technology of=20 the Dresden Technical University, concludes that BPL efficiency = suffers=20 from the mains =93impedance instability=94 resulting from totally=20 uncontrollable consumer on- and off-switching. 6. Right now, BPL is an outdated systemElectronic devices and modulation systems used for BPL draw on = the=20 latest technical developments in order to assure proper data = transmission=20 on since long heavily polluted power wires. Compared to = alternative=20 techniques, the BPL data transmission system, with a data rate = limited to=20 some 2 MB/second, does not even match ADSL (data transmission on = telephone=20 wires at 8 MB/second) commonly presented to the public. Amateur = radio=20 operators consider cable TV data transmission a valuable = alternative. ADSL=20 also, provided that nearby amateur radio frequencies be protected = by=20 adequate filtering. These amateur radio reserves do not in any = case extend=20 to future alternative solutions such as fiberglass cable, = microwave=20 systems for small cells or the oncoming UMTS mobile system. 7. BPL is exposed to eavesdropping and = malicious=20 jammingLike all radio signals, BPL can be intercepted and copied by = anybody in=20 the home or building. Therefore, providers will take steps to = secure BPL=20 transmissions. Protection efficiency will depend upon securing = measures,=20 which ordinary end users cannot control. Users have no means to = evaluate=20 risks and cannot decide when to protect themselves. Since no = connection is=20 needed, eavesdropping is easy. Considering the expected numbers of = users,=20 illegal copying will rise to unheard of summits, and the = foreseeable lack=20 of data security is extremely high. Since radio transmissions are = exposed=20 to interference, a user terminal can easily be disturbed by a = nearby=20 jammer, even with low power. 8. BPL interference breaks the freedom of=20 informationBPL can totally disrupt short wave broadcast reception = cherished by our=20 foreign fellow-citizens, as well as medium wave broadcasting and = other=20 radio services, such as the international Amateur Radio service. = This is=20 an infringement of Article 10 of the European Convention on Human = Rights=20 (fundamental right to active and passive freedom of information) = since=20 access to not otherwise accessible information is denied. On the = other=20 hand, practically all information and services offered by BPL are=20 accessible through other and at least equally valuable or better=20 techniques. 9. BPL raises completely new legal issuesProblems related to the delivery of data by power companies to = end=20 users at the limit of the property or at the power outlet in house = (as=20 well as the technical and legal liability for the BPL connection = and for=20 the content of the BPL exchange), refusal of citizens to accept = the=20 presence of BPL data on their property, endangered freedom of = information=20 and lack of data safety as well as questions about the applicable=20 legislation on electromagnetic compatibility (EMC) in case of=20 interference, raise legal issues and endanger good = neighborhood. 10. BPL is not economically justifiedCompared to other data transmission systems, BPL is a waste of=20 economical resources. In the United Kingdom, the promoters of BPL = withdraw=20 soon after some initial enthusiasm. Taking into account the cost = and the=20 return ratio of BPL, it is foreseeable that market mechanisms, = once=20 coverage becomes widespread, will confirm likely negative results. = The=20 limited range of BPL restricts the implementation to densely = populated=20 areas, where a multitude of users has to share a limited = bandwidth. 11. BPL's efficiency does not meet the growing = need of=20 quick data transmissionIn distributed workplaces, professional computers nowadays show = data=20 transmission rates of 100 Mbit/s. Industry prepares a norm based = on 10=20 Gbit/s. Professionals agree that datatransmission to PC terminals = follows=20 the law of Moore, stating a two-fold increase of processing speed = every 15=20 to 18 months. Personal computers of individual users will benefit = of this=20 technical development. Evidently, the projected BPL data rates of = some two=20 Ambit/s from provider to user will be outdated once widely spread. = Shareholders of BPL promoting concerns should be aware of this = when making=20 decisions on the stock exchange. 12. OppositionOpponents expressed their concern in a public hearing on = frequency=20 management presented by the German regulatory authority, more = precisely=20 about the norm NB 30. Significant is the negative position taken = up by=20 representatives of safety services, military, broadcasting,=20 internationally renown manufacturers of short wave equipment and = audio and=20 HF measuring instruments, other radio services and short wave = users such=20 as radio astronomy. 13. Their experimental service threatened to = death, the=20 radio amateurs strongly oppose BPLUsing very sensitive receivers for their experimental service, = radio=20 amateurs are especially concerned. In an official hearing of the = German=20 ministry of trade, they firmly expressed their opposition to BPL. = Amateur=20 radio operators have observed pilot projects, measured and made = available=20 the interfering signals. The DARC has participated as observer to = tests=20 performed by the spectrum surveillance service. Radio amateurs = have taken=20 part in press conferences of future BPL providers and their = questions have=20 given rise to considerable uncertainty. Radio amateurs, primarily=20 concerned, have produced press releases against BPL, participated = to TV=20 programmers, given interviews to local newspapers and alerted the = European=20 and the German members of Parliament. The DARC has exposed the = issue to=20 EUROCOM (European Union workgroup of the International Amateur = Radio=20 Union) as well as to the IARU conference and to the radio amateur=20 community throughout Europe and worldwide. Common action of = European=20 amateur radio societies has been developed. Outside of Europe, = progress=20 was noted in New Zeeland and in Australia where radio amateurs = showed=20 considerable awareness and concern about these critical = developments. Karl Erhard V=F6gele, DK9HU California = firm develops=20 interference free BPL technologyCanadian radio amateurs using the high frequency and VHF = spectrum are=20 becoming concerned that proposed broadband over power line (BPL) = systems=20 may render the bands unusable due to radiation from the power = lines.=20 Broadcasters and government agencies also fear that BPL radiation, = including harmonics, have the potential to cause interference to = VHF TV,=20 FM radio and military and public safety communications in the HF = and lower=20 VHF spectrum. Six weeks or so ago, I read a story that a California company, = Corridor=20 Systems, has demonstrated a BPL system that works at 2.4 and 5.3 = GHz. The=20 system, is designed to provide broadband (250 MHz) transmission = suitable=20 for high speed Internet access, using the existing power = distribution=20 system, but which does not pose any threat whatever to amateur = radio or=20 other users of the rf spectrum. I tracked down Corridor Systems Chief Technology Officer, a = radio=20 amateur, Glenn Elmore N6GN, and he assured me that their BPL = technology=20 would not interfere with the HF ham bands. The story below is = based on=20 information found on the Corridor Systems web site. Corridor Systems has developed and patented core technology = that=20 enables very high capacity, symmetric and full-duplex information=20 transport over a variety of propagation medium types. Power=20 Corridortm is an implementation of this fundamental = technology=20 which operates, in part, over a single conductor of an = unmodified,=20 existing power line. In Power Corridor&tm; , = information-carrying=20 energy is coupled on and off the conductor by identical launch = devices at=20 each end of conductor segments. This energy, which may extend from = VHF=20 through the microwave portions of the spectrum, is launched as a=20 surfacewave mode around the conductor. Surfacewave transmission on an insulated single conductor was = first=20 discovered and presented by Goubau1 in the early 1950's = and=20 known as G-Line2 after the inventor. The = characteristics of=20 surfacewave propagation, when used with a variety of = dielectric=20 types, thickness and specially prepared conductors, have been = taught and=20 available in reference texts for many years3. Though = not widely=20 utilized in practice, the mode can exhibit extremely low radiation = and=20 transmission losses from VHF into the microwave regions. Corridor Systems has discovered, extended, developed and = patented=20 a much more general surfacewave mode for operation on lines = which may=20 be completely uninsulated and which need not have any special = surface=20 preparation. Additionally, lines which are much larger in diameter = than=20 those of previous work may be utilized. This invention, which = makes=20 possible very high rate information transport over existing = medium-voltage=20 electric utility power lines, is called E-line&tm;. As with = G-line,=20 the vast majority of energy propagates within a volume located = relatively=20 close to the single conductor. In Power Corridortm the = diameter=20 of this volume is only a few inches. Since the energy propagates = at very=20 nearly the speed of light, the relative velocity of propagation in = this=20 mode is quite close to unity. Combined with the normal clearances maintained for aerial = medium and=20 high-voltage power lines and Corridor System's specially developed = and=20 patented launching devices, E-linetm provides an = extremely=20 effective mechanism for the transport of very high speed = information over=20 existing power line grids. Measurements at ground level directly under the power line used = during=20 the test showed a maximum radiated power level of less than -10 = dBm, 20 dB=20 less than the typical power level from 802.11 based wireless = cards. Corridor Systems has tested and demonstrated simultaneous = operation of=20 its BPL technology and amateur radio HF communications. Utilizing = a 100=20 watt, 7 MHz, 21 MHz and 28 MHz amateur SSB/CW transmitter = connected to a=20 dipole antenna located within 20 feet of an operating BPL system, = there=20 was not any evidence whatsoever of the operation of one system in = the=20 other. Amateur UHF communications at 446 MHz and at a 25-watt = power level=20 were similarly unaffected and in turn were not detected by the BPL = system.=20 Examination of the .1-30 MHz HF spectrum with a quality = communications=20 receiver also revealed no evidence of the BPL system. Glenn also told me that Corridor's demonstration not only used = the=20 unlicensed bands, FCC Part 15 in the US, but also simultaneously = supported=20 fast scan amateur television with stereo audio under Part 97 of = the US=20 Rules. So while the system was being used to support high speed = internet=20 traffic it also served as an =93open band=94 for amateur radio = uses-- even=20 with one end of the TV link mobile on the roadway near the power=20 lines! More information and photos can be found at: |
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