Motorola Inc’s Codex unit has been justifying the CCITT V.fast Rapporteur Group’s decision not to adopt an interim 19.2Kbps data rate for the new modem standard: according to Ray Wright, director of worldwide transmission products with Motorola Codex, the suggestion – made by AT&T Co – was rejected for two reasons: firstly because there didn’t seem much point in coming out with something less than you could achieve, and also because the technology AT&T was proposing was an extension to the existing V.32bis standard – it was felt that stretching this to achieve 19.2Kbps data rates could prove to give ropey perfomance on anything less than perfect lines. By contrast, the work being done on 28.8Kbps effectively defines the standard from scratch, and Wright reckons that performance at the higher speeds is therefore much increased. Wright did, however, welcome the news from AT&T Paradyne that it has achieved 28.8Kbps using its own V.fast modem, since he takes this as a sign that AT&T is now committed to implementing the faster speed following rejection of its interim 19.2Kbps suggestion. Motorola is firmly in the camp that believes V.fast products will make their way into the market in 1994, with broad agreement on the standard by the end of next year, and actual products following shortly afterwards. Suggestions by companies such as Sonix Inc that the timescale will be a lot longer are felt to be unduly pessimistic. Wright is, however, keen that when it emerges, V.fast should be a fully-defined and practical standard, saying we didn’t want to come out with a standard that was more a hope than a reality. Motorola has also confirmed that V.fast’s 28.8Kbps maximum data rate is very likely to be an option rather than mandatory, and that some users may not be able to achieve it at all over PTT lines. The company says that the very high baud rates that such a speed demands means that the CCITT will very likely decide that 28.8Kbps should not be a compulsory part of the standard. For the same reason, the company feels that the maximum speed may not be agreed by PTTs. These are eventually expected to announce a maximum data rate they believe is achievable, although none has yet said what this is likely to be. British Telecommunications Plc says it is not currently testing V.fast modems over its network – it is waiting until it is fully defined – but does not see any problem provided the standard is up to scratch.
