HDTV Design Rivals Will Work TogetherBy Karen Kaplan
Members of the MIT Advanced Television Research Program have agreed to cooperate with their former rivals and jointly design a format for high definition television which will become the official U.S. standard for this revolutionary television technology.
Five years ago, the Federal Communications Commission invited proposals for a national standard for HDTV, which is expected to change the face of television the way color TV did when it was introduced in the 1950's. Only four systems, including one proposed by MIT, have withstood years of rigorous testing. The FCC encouraged the designers of these systems to cooperate on developing one standard that would incorporate the best features of all four, said Jae S. Lim '74, a professor of electrical engineering and computer science who heads the MIT research group that developed one HDTV system.
In addition to MIT, the finalists included proposals made by General Instrument Corporation; Zenith Electronics and the American Telephone and Telegraph Company; and the Advanced Television Research Consortium, which includes companies such as Philips Electronics, Thomson Consumer Electronics, NBC and the David Sarnoff Research Center.
"By working together, we're combining the best components of all the systems," Lim said. "I think we will have a better system than any one single system. If we had continued on the path of competition, there would have been a significant delay" in bringing the technology to the market, Lim said.
Federal regulators, who had encouraged but not forced the alliance, also hailed the decision to cooperate on the system's design, saying the agreement eliminated technical disagreements and legal wrangling that could potentially have lasted for years. Now, high definition television could be widely available as early as 1995.
In all four of the final proposals, television signals are transmitted in the same digital language used by computers. This allows for crisper pictures than today's televisions, which use the less precise technique of transmitting signals through electromagnetic waves that are analogous to light and sound waves. In addition to increased picture clarity, HDTV's advantages include smoother motion, a better aspect ratio, and a sound system of compact disc quality.
The incorporation of digital technology also means that high definition television will be able to interact with computers to provide a variety of services.
Scanning format disputed
Most aspects of the final design have been agreed upon, but one technical disagreement has surfaced regarding scanning format, Lim said. There are two ways to scan a picture. The "progressive" scanning technique uses an electron gun to scan each row of pixels on the television screen from top to bottom 60 times each second. The "interlaced" scanning method scans all odd-numbered rows and then completes the picture by scanning the even-numbered rows, repeating this process 30 times each second. The interlaced method is used in traditional television sets to insure uniform picture brightness, but Lim says it is an outdated method for insuring picture quality.
The four research groups have agreed to use six scanning formats, five of which were proposed by MIT and utilize a progressive technique. The sixth format is based on interlaced scanning technology, and MIT objects to it.
"Interlaced scan transmission is based on the old way of doing things, and really has no place in the new television system standard," Lim said. "MIT will continue to work towards the elimination of that scanning format," which he says is responsible for the bulk of the system's technical problems.
The six proposed formats are of varying levels of quality, allowing some programs, such as television movies, to be broadcast with the highest resolution, while other programs, such as afternoon reruns, could use a lower quality format at less cost to the broadcaster.
Lim suspects that the interlaced format was included in the proposal because "television manufacturers, like Philips and Thomson, have invested a great deal of money in the technology for that kind of format. That's in the interest of those companies. We are interested in the nation's interests, and that sixth transmission format has got to go."
In all written agreements on the matter, MIT scientists have included a footnote expressing their objection to the interlaced format. Lim predicted that even if the interlaced format were included in the final system proposal to the FCC, it would be eliminated by federal regulators. "My guess is that when the FCC looks at it from our country's national interest point of view, the decision will be obvious," he said.
Because of the work done in Lim's television research laboratory, MIT will receive a portion of the overall royalties stemming from HDTV. The value of those royalties is highly speculative, since it is difficult to predict how many high definition televisions will be sold, Lim said. However, he estimated that as a result, "students' tuition might go down by $50 for some number of years."