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A two-in-one fix for digital TV

Giving new hope to the beleaguered digital TV service, Zenith Electronics Corp. and NxtWave Communications Inc. said last week that they have been working together for the past five months to develop and license technology to improve DTV reception.

More than 200 stations are on the air with DTV signals, using the FCC's 8-VSB transmission standard. But the service has been handicapped by poor reception, particularly indoors and in areas prone to multichannel interference. Only 150,000 DTV receivers have been sold.

The alliance is attacking the 8-VSB problem by combining Zenith's E-VSB transmission technology with NxtWave's new error-correction decoding chip for receivers. The E-VSB system piggybacks a second data stream designed for reception in weak signal areas on to the 8-VSB signal.

In January, the Advanced Television Systems Committee asked for proposals for improving the 8-VSB system. NxtWave, which wants to sell DTV receiver chips, and Zenith, the developer of the original 8-VSB system, were two of 10 companies that responded.

After reviewing all of the proposals, NxtWave President Matt Miller recognized the similarities between the NxtWave and Zenith plans and approached Zenith about a joint effort. Zenith agreed and the two have been working together since March.

"Working with NxtWave enabled us to look at the reception problems from a new perspective and I think that together we have come up with a system that's better than the two separate proposals and solves all of the issues," Zenith Senior Vice President Richard Lewis said.

The NxtWave-Zenith system is "backwards compatible," Miller said. Existing digital receivers will be able to receive the new signals. New receivers with the enhanced technology will be able to decode both a standard 8-VSB signal as well as the enhanced signal, with improved multipath performance of both.

"We've been able to come up with a system that improves multipath reception for the normal signal, and a second stream that can be received at much lower power levels," Miller said. "To be successful, you've got to build a receiver that can receive a much weaker signal."

The Specialist Group on RF Transmission within the ATSC (also known as T3/S9) is currently reviewing the various 8-VSB improvement proposals and is trying to put together a system that draws from several of them.

"We always encourage our participants to work together," said Mark Richer, executive director of the ATSC. "Sometimes technologies are eliminated, and sometimes they are merged. It's not often that a single technology gets incorporated as a standard in its entirety."

Richer said that compatibility with existing receivers was a critical requirement that all of the proposals had to meet in order to be considered.

Other companies that submitted proposals include ADC Telecommunications, Broadcom, Conexant Infotainment Systems, Merrill Weiss Group, Patel-Limberg-McDonald, Oren Semiconductor, Philips and Sarnoff Corporation.

According to Richer, the Association of Maximum Service Television and the FCC will begin testing prototype equipment based on the proposals by the end of the year. Those tests will continue into the spring, he said.

Once results are in, the T3/S9 committee will make its recommendation to the entire ATSC next summer. The final specification should have no problem getting approval from the FCC, Richer said, since it will reflect an industry consensus.

Broadcasters will not be required to use the enhanced 8-VSB system. "The important issue for us is that the focus is on backward-compatible strategies," Richer said. "What the enhancement ultimately does is give broadcasters flexibility. Whether they choose to use the new spec is up to them."

That flexibility includes the ability to use the second data stream to carry an additional channel of programming, ancillary data or foreign-language audio, said Zenith's Lewis.

The NxtWave-Zenith agreement also simplifies the licensing process, said Lewis, as Zenith will serve as a one-stop shop for consumer electronics manufacturers that want to include the technology in their next-generation integrated digital televisions and separate set-top receivers.

Although he would not get specific, Lewis said that a future ATSC system license that includes the new enhancement technology will cost the same as the current license.