Strange carriers

norweb communications, an international gas and electricity group in the uk , is developing techniques to use electric cables instead of phone lines to transmit data into homes. The method would ensure that data could be transmitted without any problem.

The group has developed a method to send Internet data to an electricity sub-station through optical fibre, coaxial cable, or twisted copper wires. The Internet signal is injected into power cables after it leaves the electricity sub-station. Then it is transported into home by modu-lating high frequency carrier waves. The signal is imposed on a much lower frequency. Then it is extracted from the power line by a filtering unit set close to each domestic meter. It is then delivered to a pc via conventional coaxial cable.

For the moment, Norweb is using a special printed circuit board or card in the pc to handle the Internet data. When the system is produced in volumes, the data will be delivered to a stand-alone "black box" capable of being plugged into a pc , or other devices such as television sets, network computers and games consoles.

One possibility would be a flat screen embedded in a kitchen worktop through which recipes would be retrieved from the Internet. According to Norweb and its partner Northern Telecom (Nortel) of Canada, the system solves three problems that are hindering the take-up of Internet in the home -- access to home, data transmission rates, and capital cost. The companies unveiled a technological breakthrough in delivering Internet data over power lines. They hope to provide commercial services within two years. Market trials are expected to take place in the uk during early 1998 .

For the moment, however, the Norweb and Nortel breakthrough applies only to Internet data. The transmission of voice and video will only be possible after further refinements of the technology. The new technology will be marketed mainly in Asia pacific region and in the Europe.

Information Science & Technology