Thursday, May 28, 1998 Published at 19:09 GMT 20:09 UK
Streetlamps dim hopes for Internet highway
Information on the interent could have, unwittingly, been broadcast by streetlamps
A bright idea to turn the electricity mains into an information highway has hit an unexpected obstacle - streetlamps.
Technicians testing the system in Manchester found lights using the same power supply as potential Internet customers became aerials, broadcasting downloaded data as high-frequency radio waves.
Experts fear that if the scheme was widely adopted, Web transmissions would flood the airwaves, disrupting emergency communications and amateur radio signals, and interfering with the BBC World Service.
There is even a suggestion that they might upset the operation of Britain's electronic communications base, GCHQ.
The Digital PowerLine system from Norweb, a joint venture between United Utilities and the Canadian telecommunications company Nortel, transfers data between electricity substations and people's homes via the mains.
A conventional optical fibre cable connects the substations to the Internet.
The system can download data 20 times faster than normal domestic modems while leaving telephone lines free and is expected to bring about a revolution in Net access.
But according to the New Scientist magazine, engineers conducting the Manchester trial forgot to take account of the physical characteristics of streetlamps.
The chief engineer with radio systems consultancy Great Circle Design, Nick Long, told the magazine: "If you set out to design radio aerials to fit with this system, they would look like streetlamps.
"They are just the right vertical length of conductor."
Data downloaded by users of the system was broadcast by the streetlamps as radio waves with a frequency of between two and 10 megahertz.
Mr Long warned that if the technology was not modified some sections of the radio spectrum would become unusable.
In theory, the activities of people on the Internet could also be tracked by anyone monitoring the transmissions.
British users of the affected frequencies include the BBC, Civil Aviation Authority and GCHQ.
A GCHQ spokeswoman told New Scientist: "We are trying to gauge the level of risk."
The Department of Trade and Industry's Radiocommunications Agency is said to be holding meetings with Norweb in the hope of finding a solution.
John Seddon, operations director for the company, was confident that the problem would not be a major hurdle.
"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," he said.