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here? BPL is coming . . . . . . and not everyone is overjoyed about it! Last introduced Netcomm’s Lastmonth monthwe we introduced HomePlug, device which uses the Netcomm’sa HomePlug, a device power the home or office whichlines useswithin the power wiring to network within thecomputers. home or office to Broadband over Power Lines (BPL) network computers. takes that idea andPower multiplies by Broadband over Linesit (BPL) many of magnitude. takesorders that idea and multiplies it by many orders of magnitude. T outed as one possible answer to regional Australia’s lack of broadband in the bush, BPL has already undergone a number of trials in Australia and New Zealand, with a large-scale “trial” now under way in Hobart, Tasmania. Aurora Energy (the principal electricty supplier for Tasmania) had already conducted a small-scale trial of BPL in Hobart. This trial, which lasted just two months, was limited to just four houses and two floors of the Aurora Energy building in Hobart. The system used in the trial was based on the DS2 chipset which utilises Orthogonal Frequency Division Multiplexing (OFDM) – with multiple discrete carriers approximately every 1.1 kHz between about 1.6MHz and 30MHz. Apparently Aurora considered the trial a success – so much so that they have now launched a much larger trial over a wider area. And if the somewhat contradictory wording of the Aurora press release (see right) is to be believed, this new trial is the fore runner to a statewide rollout in the not-too-distant future. But what is BPL? In a nutshell, BPL turns the electricity grid into a giant computer net8  Silicon Chip Copyright (C) 2004 Christopher D. Russell – Used With Permission – http://chrisrussell.net work with very fast (they claim up to 200Mbps) internet access. It can work on power lines at local (240/415V) level right up to the many thousands of volts used for area power distribution from zone substations (22kV and 11kV are common in Australia). With the promise of delivering fast broadband to customers without significant new (and costly) infrastructure, BPL has been a pipedream for years – particularly among those who already have a big wired network in place (like power authorities!). It works by impressing a high frequency, digitally-encoded signal onto existing power lines. While this is not a new idea, until relatively recently one major stumbling block was the presence of transformers in the system. These not only reduce the high voltage distributed around the country to more usable levels, but also act as very effective blocking inductors for frequencies significantly above the frequency of our power system, 50Hz (or 60Hz in some overseas countries) . As ever, technology marches on – and technology found a way around the problems, including highfrequency bypasses to get around the transformers. And because the frequency used by BPL is very much higher than the 50Hz mains, it is “relatively” simple to extract the new signal from the mains and use it in much the same way as more traditional broadband delivery methods. That high frequency highlights just one of the significant problems many people are finding with BPL. Depend- This PC was part of the first Tasmanian trial, set up for Aurora Energy staff to try out – with an invitation to do so on top! The white box (alongside monitor) is the interface between the PC and the power line. (Photo WIA). siliconchip.com.au by Ross Tester ing on the system used and the provider, BPL uses a slab of frequencies between about 1.6MHz and 80MHz. This, as readers would no doubt realise, encompasses a fair bit of the MF band (that’s just above the AM broadcast band), the entire HF band (3-30MHz) and a reasonable bite out of the lower VHF band. Poor HF conductors but great radiators That in itself might not be so bad if the HF signal could be contained. But street power wiring is just bare wire, with no electrical shielding at all. Those wires stretched in the air from pole to pole make magnificent antennas, radiating interference right across the spectrum. Even the power wiring within your own home will radiate interference – it too is not shielded, only insulated. It’s not hard to understand that power distribution lines make very poor HF carriers anyway. They were designed for 50Hz AC. At a pinch, they could be expected to perform reasonably up to, maybe, a couple of hundred kilohertz – not the tens of megahertz used for BPL. That’s just another reason that BPL has had some rather significant technical hurdles to overcome. According to the BPL people, they have done just that. According to opponents, they have done nothing like that. In a BPL trial currently under way in Cottonwood, Arizona (USA), amateurs report that HF bands are not usable within 70m of the power lines and the interference can still be heard nearly a kilometre away. BPL interference sounds like particularly bad “static” in the receiver, all but wiping out the ability to listen to even strong, local signals. As for the weak, overseas contacts which amateurs strive for . . . forget it! Australian amateur operators, with frequency allocations at 1.8MHz, 3.5MHz, 7MHz, 10MHz, 14MHz, 18MHz, 21MHz, 24MHz, 28MHz and 52MHz, are hopping mad. Via their peak body, the WIA, they have launched a major drive to force authorities to stop BPL before it gets a foothold. They cite S197 of the Radio Comsiliconchip.com.au PRESS RELEASE Datafast in World First Broadband Over Power Line Deployment 13 September 2005 Partners Mitsubishi Electric and Aurora Ene rgy in Commercial Roll-Out of New 200Mbps Communications Technology Datafast Telecommunications Limited (ASX :DFT) today announced the launch of the world’s first large-scale comm ercial trial of 200 Megabit Broadband over Power Line (BPL) technology , in conjunction with Aurora Energy and Mitsubishi Electric. BPL delivers ultraband Internet access at up to 200Mbps – speeds vastly quicker than any DSL technology, dwarfing effor ts to coax 24Mbps from existing telephone lines with ADSL 2 and 2+. The commercial trial is the first step in linkin g Aurora Energy’s extensive electricity network throughout Tasmania – near ly 25,000 kilometres reaching 250,000 homes and businesses – with leadi ng edge technology from Japan’s Mitsubishi Electric. Datafast CEO Simon Ehrenfeld said, “Mitsubish i has delivered something genuinely exciting, not just for geeks but also for the business people in our industry. We anticipate excellent results from the commercial trial, and we believe that the partners in this project have a three year head start on other Internet providers. This is not a techn ical trial – the technology works. This is the first stage of a commercia l roll-out.” “We are providing significant expertise in the areas of data management and billing systems. Datafast’s intellectual prop erty has been developed in-house over a long period, and enables the simple and effective management of complex Internet session data.” Mitsubishi has only recently released its comm ercial 200 Megabit BPL product and Aurora is one of the first comp anies in the world to deploy this new technology commercially. The commercial trial launched today will run for approximately nine months – initially with customers in Hobart and then extending to other parts of the State. This trial will offer broadband data as well as “Voice-over-IP” services via existing power points in homes and busin esses. A smaller number of customers will also be involved in trials of video via the power point during this period. BPL is attracting interest around the world with some of the global electronics and communications companies – such as Mitsubishi, Sony and Panasonic – joining forces to ensure integratio n into every home appliance, from fridges to air-conditioning units. November 2005  9 Power Generation and high voltage transformers HV (110-330kV and more) Distribution HV Substation and BPL input MV (10-25kV) Distribution Transformer HF Bypass and Coupler Low Voltage (240V) Street Distribution A somewhat stylised and simplified diagram showing the power distribution system and how Broadband over Power Lines is made available at street (and therefore home) level. There is no doubt that BPL works well and offers many advantages such as speed and existing infrastructure. There is also no doubt that those long power lines act as magnificent radiators, blotting out much of the MF, HF and VHF bands. munications Act, 1992, which protects radio communications services from “substantial interference”. Whether by fiendishly clever design or simply dumb good luck (we’ll leave you to make up your mind which) BPL has avoided heavy-use areas of the spectrum where there could be huge public outcry. BPL frequencies are above the AM broadcast band (though BPL harmonics could be a problem in low-level AM signal areas). They’re below the FM broadcast band (perhaps ditto, perhaps less likely). They have even avoided most VHF TV channels. And of course they’re way below mobile phones. They are, however, right over the top of HF CB radio. Then again, that might not be such a bad thing (have you listened to 27MHz CB lately??). Interference back at ya! Amateurs aren’t just concerned about the ability of BPL to dramatically curtail amateur radio activities. It goes back the other way. They have convincingly proved that a fully legal, licenced and operationally correct HF radio transmitter has the ability to stop BPL dead in its tracks. And they have the documented evidence to back up the claim. Even operating a relatively low 10  Silicon Chip Coupler and Backhaul Broadband Service Provider Each home has powerline modem power transmitter in the vicinity of a BPL user is highly likely to interfere with BPL so severely that the user’s computer either rejects it all as garbage or maybe even crashes, leaving the broadband user believing that they were “wronged” by that *&$%<at># ham radio geek next door. Following decades of complaints about interference to neighbour’s radio and television services (RFI and TVI), amateurs are now faced with unwarranted and underserved flak from BPL users, who don’t understand the notion that the licensed amateur radio operators are doing nothing wrong and, indeed, “were there first!” In many, perhaps most, cases the amateur can show that the neighbour’s equipment is at fault, not their’s. But does that matter? If previous TVI experience is any yardstick, amateurs expect that authorities will demand they cease operation, then – perhaps – try to find cures for the problem, rather than upset powerful media organisations. Years of experience suggests that when it comes to TVI and RFI, even when amateur operators are right, they’re wrong! Amateur operators in many other countries have launched similar campaigns to those in Autralia. The US American Radio Relay League has a neat BPL analogy: using the traffic Here’s part of a BPL installation in Briarcliffe Manor, NY state, USA, which was responsible for a large amount of interference in the area. The ball-shaped object under the high voltage cables at the top of the pole is responsible for extracting the BPL signal; the grey box then impresses this signal onto the low-voltage cables feeding homes and businesses. (Photo N2YGK). siliconchip.com.au lanes of a busy, multi-lane freeway as a garbage dump. It’s not just amateurs . . . While it seems that amateurs have made the most noise, they aren’t the only ones who are worried about BPL. Their concerns are echoed by emergency services, the military, HF business radio users and many others who have already experienced the disruption BPL can cause. Even the Salvation Army has lodged objections in the US! In some areas, BPL has already been banned (or at least put on hold), primarily due to its proven interference potential. Shortwave radio listeners will be seriously affected. Many of the stations listened to are already “down in the mud” – imagine how much worse that will be with continuous, loud, crackling, interference. And with many third-world countries looking at BPL as a low-cost way to join the broadband club, services to those areas from organisations such as Radio Australia might be in jeopardy. It’s getting quite nasty On the other side of the equation, BPL advocates represent a powerful lobby group and are using that power to convince regulatory authorities that they are not the threat their opponents claim them to be. They maintain that they can “notch out” interference near the homes or premises of affected users. Opponents counter this by claiming that if they notched out all affected frequencies, particularly in a major city, then there would be no spectrum left for BPL to work in! Moreover, this doesn’t take into account mobile radio users – you can’t notch them out! And there are countless reports of “notched out” fixed operators still being basically forced off the air by BPL interference. Opponents are also very quick to dispute the wonderful claims made by BPL suppliers, and there are plenty, as propaganda from vested interest groups with big $$$ to back them up. Most of the positive – in some cases downright glowing – BPL reports in the media are dismissed as simply paid-for PR, with the negatives never mentioned. Indeed, amateurs are crying “dirty pool” when it comes to many media siliconchip.com.au reports, even here in Australia. They claim that BPL interests are playing the man, not the ball, trying to discredit both the amateur organisations and the people they represent. It has become quite nasty at times. Amateurs are also keen to point out that they are not anti-broadband, per se. They maintain that, as technically qualified people, they are often at the forefront of development of new technologies and equipment; they are in fact often the “early adopters” of such. Power Line Control Some readers might be wondering about the difference between Power Line Control (PLC) systems, which also impress signals on the power lines, and BPL – and why there haven’t been significant complaints about PLC (which has, after all, been around for decades). The most common PLC signals are those which are used to switch “off peak” water heaters, etc, on and off. There are two major differences between PLC and BPL. First, PLC signals are usually below 500kHz (often 150-180kHz), so are nowhere near as threatening as HF/VHF signals. Second, and probably more important, is the very intermittent nature of PLC signals – just a few seconds every few hours. BPL is the opposite – it can be virtually continuous, depending on the user and usage. The last mile The last mile is an expression used by service providers to denote the link to actual users, the paying customers. It has nothing to do with any measurement (indeed, most last miles are a lot less than a mile!). Here BPL gets at least a little interesting. In some trials in the US, BPL has been much as described here, with adaptors plugged in to the power line. However, in others, they’ve used WiFi links, either very local ones from the poles to houses and offices or, in some cases, they’ve created higher power WiFi WANs (wide area networks), capable of servicing perhaps a block of houses or office buildings. There is plenty of “last mile” development going on at the moment; it is quite likely that there will be even more innovative approaches. Just as long as they solve the interference problem first! SC An addendum: EOP Interference A number of readers have questioned the amount of interference to HF/VHF radio from the NetComm NP210 “HomePlug” Ethernet Over Power (EOP) devices which we reviewed last month. To be honest, we tried to look at radio interference at the time of the review but as Murphy would have it, at that exact moment (quite literally the day before our October deadline) my old Yaesu HF transceiver decided to give up the ghost and I couldn’t quickly lay my hands on another communications (HF) receiver. I can’t blame the Yaesu – it’s been a long time since I last used it [in fact years, since I ceased renewing my amateur station licence – I couldn’t justify contributing to Government coffers for the amount of use it got] and it did/does live in a fairly salt-air coastal environment. Anyway, since then I have managed to repair it and rigged it up once again. After a dial-twiddle through the entire band (0.5-30MHz) to get some feel for the amount of current “background” interference, I fired up the HomePlugs and repeated the exercise. The difference was, to say the least, alarming. In many places through the HF spectrum, where the background QRN/ QRM had been hardly bothering the Smeter, it was now S5-S7, peaking S8, and rendering those bands virtually unusable. I guess the closest analogy I can make is continuous thunderstorm crashes on a distant AM station, with an underlying modulation. (In fact, you could watch the NP210 activity LED flash in sympathy!) The bands 4.5-6.9MHz, 8.0-9.9MHz, 10.5-13.9MHz, 14.5-15.1MHz and 16.520.8MHz were all badly affected. Now I’m not a conspiracy theorist – but notice that the 3.5, 7, 10, 14 and 21MHz amateur bands are all missing from this list? Could the manufacturers deliberately have notched out those bands to minimise complaints from amateur bodies? Nevertheless, if the interference from a single, low power EOP device is this bad, I hate to think what a broad-scale BPL implementation is going to do to all radio users, not just amateurs. So far, I haven’t had the fortune (?!!) to experience real, live BPL interference – I have listened to it extensively via examples on the ’net (Google BPL interference . . .). If that’s what the future of broadband promises, perhaps it’s time to apply the brakes and re-think. November 2005  11