Engineering News

Focus sharpens on high-definition TV

Paris-Even its biggest proponents can't deny that high-definition TV has had its problems.

First Japan invested heavily in an analog standard, but that's expected to be obsoleted by digital technology. In 1992, a European standards effort ran into problems with ground-based systems that couldn't handle HDTV-quality pictures. And in the U.S. that year, the Federal Communications Commission declined to adopt a standard among six that were proposed.

Today, HDTV is once again riding the crest of a wave of media attention. But things have changed. Rather than focusing on building an HDTV standard that would pack more pixels into a video image, the European community has turned its attention to developing a digital transmission standard. More than 130 companies, competing for digital business in Europe, have formed the Digital Video Broadcasting Group aimed at giving consumers a tremendous range of channels, based on standard television technology and digital services.

Considered a model of successful business communications, the DVB has agreed on a European digital transmission standard based on ISO-adapted Moving Picture Expert Group (MPEG)-2 standards as well as standards that address compression and multiplexing issues. Essentially, DVB compatibility will provide the key platform for multi-vendor interoperability in compression, channel coding, and modulation techniques. The first digital transmissions target cable and satellite applications.

For broadcasters, the opportunities are far-reaching-simulcasting the same service to facilitate a gradual transfer from analog to digital technology-or even simulcasting two different TV services in analog and digital format to target different audiences.

"The European community is focusing on the flexibility that digital transmission services can bring to the consumer," says Tony Wechselberger, executive vice president of TV-COM International, San Diego, CA, whose major business is in Europe, with centralized operations in Amsterdam. "It means getting many more TV channels and receiving all kinds of digital services."

The results of the effort are already showing up. In Paris, Eutelsat, the large European satellite consortium with operators in 44 countries, is simulcasting both analog and digital television signals in a single 36-MHz Eutelsat satellite transponder that does not require any extra cost to the broadcaster. And, already a number of European hardware firms including TV/COM International, Fuba, Nokia, Philips, Tandberg, and Thompson are designing decoders either for simulcast reception or for reception of a package of DVB digital television channels. Thousands of boxes are expected to be delivered throughout Europe by the end of this year.

Alliance sets the stage. In the U.S., the spotlight is focusing on the efforts of the digital HDTV Grand Alliance, formed after the FCC's Advisory Committee on Advanced Television Services (ACAT) encouraged digital HDTV groups to merge their best features into one system.

Since then, the Grand Alliance, consisting of industry giants AT&T, General Instrument Corp., Zenith Electronics Corp., the Massachusetts Institute of Technology, Thomson Consumer Electronics, Philips Consumer Electronics, and the David Sarnoff Research Center, has focused on a best-of-the-best digital HDTV system. It has successfully field-tested the transmission subsystem and constructed a prototype. Three years in the making, the final design-a new flexible, open architecture system-is


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