Lopsided modem boosts speed

COMPUTERS will soon be able to communicate across ordinary phone lines more than 60 per cent faster than at present, thanks to new chips from Rockwell Semiconductor Systems of Newport Beach, California. Rockwell already provides components for most of the world's modems.

Today's modems work at the same speed whether they are transmitting or receiving. The new technology uses a different, "asymmetrical" approach, in which chips in the consumer's modem will be able to receive data faster than they can send them. New chips will also be required for the "central site" modems commonly used by Internet service providers and large corporations.

When the upgraded central site modem recognises that a consumer modem has the new chips, it will transmit information at up to 56 000 bits per second, which is as fast as some dedicated lines in America. Although they can receive at this speed, the consumer modems will only transmit at today's top speed of 33 600 bits per second. For browsing the World Wide Web or searching corporate data, however, the slower sending speed should not hold things up, because "surfers" spend most of their time receiving data and only send short requests for further information.

A far bigger drawback is that leased lines operate differently in Europe and the US, so the new modems cannot get the extra speed on transatlantic links.

Products based on Rockwell's chips could start to emerge before the end of the year in the US, but are unlikely to be more widely available until early 1997.

David Brake

From New Scientist, 5 Oct 1996

© Copyright IPC Magazines 1996