The key modem manufacturers appear to have taken the the bit between their teeth at last month’s V.fast meeting in Bath. A joint statement put out by Motorola Codex, General Datacomm Industries Inc, UDS Motorola and US Robotics Inc was upbeat, saying that the companies expect a firm V.fast standard can be completed during 1993. A proposal by AT&T Co for an interim 19.2Kbps extension to V32bis was rejected. Among the decisions was one to increase slightly the standard’s maximum speed to 28.8Kbps. The meeting also agreed on multiple symbol rates and multiple centre frequencies for each data rate. Finally, a list of candidate trellis codes was agreed upon, and US Robotics will co-ordinate simulations of the contenders to decide which offers the best trade-off between performance and complexity. These decisions go beyond the agreements that were achieved within the US groups in July says David Forney, Motorola Inc vice-president, they reflect consensus that it’s time to move ahead with V.fast and that V.fast should aim high and include the best available technologies. Among the technologies agreed for inclusion are precoding; adaptive pre-emphasis; shaping; non-linear encoding and adaptive power control. An ad hoc group chaired by Kenneth Jones of Octocom will be working outside the formal committees on the V.Fast start-up sequence (the period during which modems negotiate speeds and protocols). The US V.Fast committee meets in Toronto this week, with further discussions set for December in Florida. Bob Jones, head of Cirencester-based UK modem manufacturer Sonix Ltd, and lobbyist for speedy V.fast development says he was encouraged by the progress made, but suggests that a firm standard may not appear until 1994. He is disappointed that the interim 19.2Kbps extension was rejected, but agrees it might have spread the development effort too thinly.
