Stanford Telecom, not to be ignored in the cable modem anddigital set-top silicon race, is out with a single chip that handles key bidirectionalsignalling functions.
Chuck Frank, vice president of Stanford Telecom Inc.'sComponent Products Group, said during a briefing last week that the new chip is importantbecause it handles both downstream receiving and upstream transmission on one chip.
Specifically, he said, the new STEL-2176 chip handles threeflavors of downstream transmission: 16 QAM (quadrature amplitude modulation), 64 QAM and256 QAM. For upstream signalling, the chip sends in QPSK (quadrature phase shift key) and16 QAM formats, he said. Portions of the chip are patent-pending.
'This is a chip that is both MCNS (Multimedia CableNetwork System) and DAVIC (Digital Audio Video Council) compliant, in respect of upstreamfrequency range modulation and forward error correction,' Frank said.
That means the chip is selectable between the 'AnnexA' and 'Annex B' portions of the QAM technique. (U.S. cable operators useAnnex A, while European operators use Annex B.)
So far, he said, the chip handles only the PHY (physical)portions of the Cable Television Laboratories Inc. DOCSIS (Data Over CableService/Interoperability Specification), but plans are under way to also include the MAC(Media Access Control) portion of that standard.
'Our philosophy has been that most of the vendors wantto do their own MAC, to maintain their own uniqueness,' Frank said, explaining thatthe MAC protocol is typically '20 to 30 percent hardware, and 70 to 80 percentsoftware' driven.
So far, he said, several vendors are using StanfordTelecom's upstream transmission chip, and are currently evaluating the condensed,multipurpose STEL-2176.
'We've been quiet because we don't make alot of noise about things we don't have -- we don't make announcements aboutvaporware,' Frank said.
Vendors evaluating the new, single chip solution includePanasonic Video Communications Co.; GadLine, an Israeli manufacturer of modems; Com21Inc.; and Hybrid Networks.
Frank said production quantities of the new chip willbecome available in the second quarter.