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A solution to the HDTV standard debacle: digital compression.

Two major technological developments, long in the making, but relatively new in the entertainment industry consciousness, are bound to revolutionize television: Digital compression and higher definition television (HDTV).

Each developed for its own sake and purpose, and each evolutionary in its own right, together they can accelerate the coming of a video era.

Digital video compression, well functioning some 10 years ago, was developed to better utilize satellite time when transponders were scarce for teleconferencing.

Today, it has found a more proficuous application in expanding cable program capacity. Specifically, HBO and other cable TV networks are experimenting with video compression, to send more than one TV program into one single satellite channel. HBO is now examining several digital video compression systems and within a year, will select one.

With a decoder, the viewer can then have the preferred selection displayed on a regular TV set. This, however, is not controlled by the likes of HBO, but an option given by the cable company.

HDTV, also 10 years in the making, was first thought of by the entertainment industry as a way to save film prints. With its resolution compatible with 35mm film, movie theaters can indeed receive (via satellite, optical fiber or even with the limited coaxial cable), the main feature electronically on HDTV, for projection on a wide screen.

But, while the FCC and other nations telecommunications regulatory agencies are still slowly investigating the best system for HDTV, the television of tomorrow is entering the viewer's homes by using existing means.

Since the television in the near future will be completely digital, including HDTV, the latter can be easily compressed to be accommodated in the existing limited technological frame.

Thanks to the high compression rate achieved today, it's possible to digitally compress the normal TV signal and put nine of them into one single broadcast channel.

The same system can be used to digitally compress the wide-band HDTV signal into one standard TV channel.

The current debate at the various government regulatory levels is how to assure HDTV compatibility with existing analog TV receivers and, at the same time, protect current terrestrial broadcasters.

While cable TV networks could easily allocate few channels to a non-compatible digitally compressed HDTV, terrestrial broadcasters have to find a compatible solution. One proposal, which already has been discarded, was to standardize an analog HDTV signal with the added HDTV portion transmitted on another channel (e.g. the standard TV program broadcast on Channel 7, and the HDTV portion on Channel 3 1). The viewers with standard sets had to tune into the traditional channel, while those with HDTV set capability would tune into both channels.

This system was limiting the future potential of television and was opposed by every telephone company, cable TV system and satellite carrier in the world. It surely would have been made obsolete by VCR technology, movie productions and screenings.

Plus, under current debates, any HDTV standard selection is bound to be more harmful to the private broadcasters than state-owned TV enterprises. The latter can better afford technical expenditures and a possible drop of viewership, due to a brief period of consumers' confusion.

A second HDTV proposal, the widely desirable digital route, is bound to make present terrestrial broadcasting obsolete, except if HDTV will be "married" to digital compression.

In this case, the unused space of a standard analog TV signal can be filled by the digitally compressed HDTV signal and transmitted over the current terrestrial broadcast channel. At the receiver -hand, an HDTV set utilizes the digital signal, while a standard TV set processes its customary analog signal.

The technical advisor for this article was Stefano Bargauan, a broadcast technology expert based in Milan-Italy.
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Title Annotation:high definition television
Author:Serafini, Dom
Publication:Video Age International
Date:Apr 1, 1992
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