The light programme


By Mark Ward ULTRAFAST Internet access via the electricity mains . . . it sounded too good to be true, and perhaps it was. Trials of the scheme in Manchester have hit an embarrassing snag. Streetlamps using the same power supply as Net surfers are acting as aerials and broadcasting downloaded data as high-frequency radio waves. If the current technology were to be widely used, experts fear that sections of the radio spectrum could be swamped, disrupting emergency communications, annoying amateur radio buffs and interfering with the BBC World Service. Britain’s Department of Trade and Industry (DTI) has stepped in to mediate between users of the affected frequencies and NOR.WEB, the company developing the system. NOR.WEB is a joint venture between the British energy supplier United Utilities and the Canadian telecommunications equipment company Nortel. Its Digital PowerLine system transfers data between electricity substations and people’s homes using a 1-megahertz carrier wave riding on top of the 50-hertz AC electricity supply (Technology, 18 January 1997, p 18). The connection from substation to the Internet is via a conventional high-bandwidth optical fibre. The system can download data about twenty times as fast as the modems used by most domestic Net useres, and also leaves phone lines free. NOR.WEB is confident that it can bring about a revolution in Net access. The company is marketing the technology worldwide. The Manchester trials delivered the impressive access speeds that the system had promised. But the company’s engineers hadn’t taken the physical characteristics of streetlights into consideration. “If you set out to design radio aerials to fit with this system, they would look like streetlamps,” says Nick Long, chief engineer with Great Circle Design, a radio systems consultancy based in Wincanton, Somerset. “They are just the right vertical length of conductor.” As a result, data being downloaded by users of the system are being broadcast as radio waves between 2 and 10 megahertz. If the technology is not modified to remove this interference, says Long, some sections of the radio spectrum could become unusable. The online activities of Net surfers using the system could also, in theory, be tracked by monitoring the radio transmissions, he adds. British users of the affected radio frequencies include the BBC, the Civil Aviation Authority and even GCHQ, the government’s electronic communications nerve centre. “We are trying to gauge the level of risk,” says a GCHQ spokeswoman. Robin Page-Jones of the Radio Society of Great Britain fears that his members will be hit hardest. “It could be very difficult in the long term to control this,” he says. “Regulations need to be nailed down now.” The Radiocommunications Agency at the DTI has been holding meetings with NOR.WEB and radio users to resolve the problem, but a solution has not yet been thrashed out. Nevertheless, John Seddon, operations director for NOR.WEB, is confident that the problem can be solved. “The technology that will be deployed in volume will be at low power levels in comparison to the general radio noise that’s already out there,
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