Television: A dream of the late nineteenth century became reality through the technology of the twentieth. In the sixty years since its crude beginnings, TV has emerged as the uncontested king of mass media. Today, the TV set supplies most Americans with the bulk of their news, and a sizable amount of their babysitting. The emotional power of motion pictures has also been packed into this innocuous-looking box, and television is widely considered a major shaper of values and beliefs. A TV set is the undisputed centerpiece of most people's living room, and not a few regard it as something of a Trojan Horse.
Therefore, it is not surprising that major efforts are underway to improve television. What may be surprising, however, is that these efforts are aimed at the technical quality, not the content.
High Definition Television, or HDTV, has been touted as the obvious next step in improving the realism of TV. It is, we are told, the "television system of the next millennium," bringing not merely a marginal improvement in viewing enjoyment, but a radical one.
According to HDTV's excited proponents, the goal is to bring the picture quality of 35mm movies and the sound fidelity of compact discs into the living room. And if the carrot of better picture and sound is not enough to excite your consumer instincts, there is always the stick of foreign competition. The Japanese and the Europeans have been racing down the track of HDTV development for years, while America is still in the starting block. Some even fear this could be the first major new technology of the last hundred years in which the United States will not play a leading role. Others see HDTV as America's last chance to get back into the consumer electronics business. And nearly everyone points out the disturbing security implications if we should become dependent on foreign countries for a technology with such obvious applications in defense.
The HDTV issue is more than a technical battle among the engineers. It has become a political issue, with consequences for the electronics industry, broadcasters, film and photo interests, and, yes home viewers.
But to best understand the current political wranglings over HDTV, it is necessary to grasp some of the technology.
Lines, Frames, and Fields
In common with motion pictures, television creates the illusion of motion by painting the face of your TV tube with many images each second. But unlike the cinema, television images come into a set one little piece after another - that is, they are built up serially. Each complete image, or frame (to borrow cinema terminology), is broken into 535 horizontal lines. The lines are drawn left to right, from top to bottom, at a rate of 30 frames per second.
Actually, this simple description of television is a little too simple. If your TV screen merely displayed 30 frames per second, you would discern an annoying flicker as the screen flashed alternately light and dark To avoid this effect at the cinema, movie projectors project each image twice, thereby boosting the frame rate from 24 to 48 frames per second. At this frequency, most people no longer sense the flicker, even if they still talk
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