Who invented High Definition Television and Where did HDTV come from?

High-definition television, the experts tell us, will deliver pictures up to five times sharper than the current standard, with a larger field of vision and with sound comparable to that produced by a compact disk.

The new system, which should be commercially available by the mid-1990s, will mark the first real change in television since color was introduced in 1954. The picture that appears on a standard television screen is transmitted as a series of images, each containing 525 horizontal lines of picture information, at a rate of thirty frames per second. All told, standard television pictures contain 212,520 dots of picture information, called pixels.

High-definition television (HDTV) will achieve its revolutionary clarity by increasing to 1,125 the number of horizontal lines that compose each image and doubling the number of frames per second. HDTV pictures will contain five times as many pixels as current pictures, resulting in rich, seamless images. This is wonderful news for TV bugs, many of whom are probably ready to shell out the $2,500 necessary to buy a high-definition set.

But the change from traditional television to high definition involves more than tuning in a hypersensitive new television set: HDTV demands a brand-new way of broadcasting television signals, and the signals will be beyond the reach of ordinary television sets.

HDTV carries too much information to fit into current broadcast channels. All those pixels can be squeezed into a standard channel about as readily as a camel can pass through the eye of a needle. Before the new sets begin appearing in stores, broadcasters must figure out how to broadcast high-definition signals without making obsolete the 160 million or so television sets now operating across the country.

To protect the consumer, the Federal Communications Commission (FCC) has ruled that HDTV will have to fit within current bands on the television spectrum. The sooner broadcasters figure out a way to comply with FCC requirements, the better, according to various electronics manufacturers who are dying to get their new high-definition sets on the market.

There are a variety of ways HDTV signals might be transmitted. One possibility would be for existing stations to send the extra signals necessary to complete a high-definition image through unoccupied channels on the television band. In local markets, to prevent interference, television stations are separated by vacant channel space.

The FCC could assign each extant station an empty channel for the broadcast of HDTV signals. A station could broadcast one set of signals on ordinary VHF (channels 2 through 13) and send the additional picture information over a blank channel. Traditional TV sets would pick up the regular channel, while viewers with high-definition sets would pull in both sets of signals, which would be combined by their televisions into a single enhanced image.

Another possibility is direct-broadcast satellite. High-definition images could be beamed by satellite to homes equipped with satellite dishes. High-definition television sets would pick up both the new satellite transmissions and traditional broadcasts.

A third idea under discussion is to use the fiber-optic cables, currently being installed by telephone companies, to carry high-definition television signals. After buying new high-definition sets, viewers would subscribe to fiber-optic cable service, in much the same way as some traditional-TV-set viewers now buy cable TV packages.

When high-definition television eventually becomes available, the new hardware will have more in common with computers than with ordinary television sets. Traditional television works on an analog system: audio and visual elements are converted to undulating electric waves for transmission to television receivers (TV sets), which reconvert the waves into visible light rays (pictures) and audible sound.

High-definition television will be digital. The new sets will convert analog waves into digital code, with strings of zeros and ones representing each bit of picture information, color, shade, placement. A microchip in the new sets will process the digital code, paying strict attention to each light element, to produce richly detailed pictures.

HDTV is not without its critics, some of whom contend that the enhanced pictures are barely discernible from those on old-fashioned TV. Even so, market analysts predict HDTV will be worth billions of dollars a year to the electronics industry; therein lies the real incentive. In the United States, where only one major company, Zenith, continues to make TVs, the financial motive is especially strong.

The good news for American companies interested in regaining a toehold in the consumer electronics market is that current U.S. and Japanese HDTV standards are incompatible. The bad news is that Japan began HDTV broadcasts in 1989, giving it a big head start in perfecting the equipment.