The Picture Suddenly Gets Clearer

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If all goes according to plan -- a big "if" when it comes to new technology -- broadcast history will be made in a meeting room on Capitol Hill this week. A new kind of television signal will leave the Bethesda, Md., TV tower of WETA, a PBS affiliate, fly across downtown Washington, strike an antenna on the roof of the Capitol building and zip down a cable into the Thomas P. O'Neill Room two floors below. There, before an audience of Senators, Congressmen and assorted commissioners, magician Harry Blackstone Jr. will draw back a black cloth and reveal the first image ever to be broadcast in digital high-definition television: a razor-sharp picture of a fluttering American flag.

The image is well chosen. Just two years ago, high-definition television (HDTV) was a symbol of everything that was wrong with the American electronics industry. After ceding most of the market for today's television sets to Japanese and European manufacturers, the U.S. was about to lose the market for tomorrow's TVs as well. It seemed only a matter of time before U.S. consumers started replacing their squat, fuzzy receivers with crisp, wide- screen sets built around a made-in-Japan technology called analog HDTV.

Now the situation is reversed. With this week's broadcast, the U.S. will seize the lead in the HDTV race, having successfully changed the venue of the battle: from the world of radio- and TV-signal processing, in which the Japanese excel, to the digital world of computers, which is dominated by U.S. firms. "The entrepreneurial spirit is alive and well in the U.S.," says Donald Rumsfeld, former Secretary of Defense and now chairman of General Instrument, the Chicago-based company that spearheaded the push to digital HDTV.

This week's demonstration, staged by General Instrument, marks a victory for those who have argued that the Japanese approach to television design is all wrong, a relic of 19th century technology that dates back to Marconi and Bell. The future, they say, is digital. To survive in a world dominated by digital chips, digital telephones and digital compact discs, the television of the future must speak in the streams of 0s and 1s that are the language of computers.

Conventional TV uses analog waves as electronic representations -- or analogues -- of the light and sound waves captured by television cameras and microphones. The Japanese approach to HDTV was to double the number of horizontal lines used to reproduce the images on the screen -- from just over 500 to more than 1,000 -- while continuing to rely on analog technology to transmit the images.

Scientists have long known that it is possible to represent the information carried in analog waves with strings of numbers. That is essentially what recording engineers did when they replaced analog records and tapes with digital compact discs. The advantages are twofold. Digital signals offer many more opportunities to identify and eliminate distortions caused by interference -- the echoes, flutters, ghosts and bursts of noise that can make today's broadcast television so hard on the eyes. Going digital also makes it easier to isolate and manipulate images -- freeze frames, enlarge pictures, even view scenes from different angles. That feature will grow increasingly important as television and computer technology begin to merge.