A new two-way transmission chip...........................................
multichannel.com
Stanford Telecom Rallies in Chip Race
By LESLIE ELLIS
Stanford Telecom, not to be ignored in the cable modem and digital set-top silicon race, is out with a single chip that handles key bidirectional signalling functions.
Chuck Frank, vice president of Stanford Telecom Inc.'s Component Products Group, said during a briefing last week that the new chip is important because it handles both downstream receiving and upstream transmission on one chip.
Specifically, he said, the new STEL-2176 chip handles three flavors of downstream transmission: 16 QAM (quadrature amplitude modulation), 64 QAM and 256 QAM. For upstream signalling, the chip sends in QPSK (quadrature phase shift key) and 16 QAM formats, he said. Portions of the chip are patent-pending.
"This is a chip that is both MCNS (Multimedia Cable Network System) and DAVIC (Digital Audio Video Council) compliant, in respect of upstream frequency range modulation and forward error correction," Frank said.
That means the chip is selectable between the "Annex A" and "Annex B" portions of the QAM technique. (U.S. cable operators use Annex 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 Cable Service/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 want to do their own MAC, to maintain their own uniqueness," Frank said, explaining that the MAC protocol is typically "20 to 30 percent hardware, and 70 to 80 percent software" driven.
So far, he said, several vendors are using Stanford Telecom's upstream transmission chip, and are currently evaluating the condensed, multipurpose STEL-2176.
"We've been quiet because we don't make a lot of noise about things we don't have -- we don't make announcements about vaporware," Frank said.
Vendors evaluating the new, single chip solution include Panasonic Video Communications Co.; GadLine, an Israeli manufacturer of modems; Com21 Inc.; and Hybrid Networks.
Frank said production quantities of the new chip will become available in the second quarter. |
