HDTV- High Definition Television

Introduction

Usually one would think that an emerging new technology either fails or succeeds, since the consumers know what they want or need, and since the industry knows what is possible and what is not. But sometimes technologies keep coming back. Critics claim them dead but a few years later, they are more alive than ever. High Definition Television (HDTV) is one of those technologies.

This briefing paper aims to inform the executives of Nice and Easy Television (NET) of the benefits and drawbacks of HDTV. It explains how this technology basically works, what problems it is designed to solve, who the major players are and what kinds of social, economic and regulatory issues have to be considered.

How HDTV works

High Definition Television (HDTV) as well as Standard Definition television (SDTV) are both parts of digital television technology (DTV). The major difference is that HDTV uses a higher resolution and therefore offers a better picture quality than SDTV or the old analog NTSC standard. HDTV can be at a resolution of 1,080 x 1,920 pixels^[1] or 720 x 1,280 pixels, while SDTV has only 480 x 704 (or sometimes 640) pixels (Braithwaite 1998, p. 38). All in all there are as many as 18 different resolution formats, but contrary to the problems of incompatible standards experienced with the different VCR formats or between IBM and Macintosh Computers, these different systems will be compatible with one another. The new generation of digital TV sets will able to receive all of the different resolution formats and display them properly (O’Malley 1998, p.52).

To understand the variety display formats, one has to understand the difference between “interlaced scanning” and “progressive scanning”. The old NTSC picture is an example of interlaced scanning: When the picture is “painted” onto the screen with a light beam, only every second line is scanned. When the beam reaches the bottom of the screen, it starts over at the top and fills in the remaining lines. Because both of the so-called “fields” are created 30 times a second, we don’t notice that what we see are two incomplete pictures.

The main advantage of this method is the reduced bandwidth that is needed for transmission of these “half” pictures.

Most of today’s computer monitors, in contrast, use “progressive scanning”, which means that all the lines on the screen are scanned in order. This way a better picture is achieved, but progressive scanning also requires a greater bandwidth transmission^[2] (Braithwaite 1998, p. 36; Tarr 1998b, p. T5).

illustration not visible in this excerpt

(Source: Braithwaite 1998, p. 36)

Apart from a better picture quality, the aspect ratio (the relation between width and height of the picture) is also different. While the conventional NTSC standard and most of the SDTV standards use a 4:3 aspect ratio, HDTV will be shown in a 16:9 aspect ratio which means that the screen is much wider than it used to be and resembles the format of a movie theater screen.

Along with the better picture of HDTV also comes improved sound quality. Six different channels will make the television sound much more realistic and enjoyable, since they enable surround sound and much crisper and clearer tones (Mitchell 1998, p. 48).

HDTVs background and who is promoting it

a) Historical Development

As stated in the beginning, experiments with HDTV technology have quite a long tradition, although its real breakthrough as a commercially viable product remains yet to be seen.

As recently as the 1970s Japanese researchers developed the first HDTV systems, using an analog format. Transmission on a regular basis began in 1989, when one hour of HDTV each day was broadcast to Japanese homes eventually growing to 17 hours per day. An attempt by the USA and Japan to agree on the Japanese HDTV standard as a world standard, however, failed in 1986 because European delegates were not willing to accept the Japanese hegemony in this important field of new technology.

After that setback, the Advisory Committee on Advanced Television Service (ACATS) was founded, with the task to advise the FCC and to create and test new possibilities to transmit HDTV. In 1993 the three major players in the field of testing digital television (AT&T/Zenith, General Instrument/Zenith and Philips/Thompson/Sarnoff) joined forces and formed the so-called “Grand Alliance”. Their combined new digital transmission standard was presented to the ACATS and the FCC for evaluation and finally accepted in 1995. This standard basically consists of the 18 different resolution formats mentioned in the above chapter, from which the broadcasters can choose freely (Seel 1998, p. 66-70).

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^[1] Pixels are the smallest “picture elements” (hence the name) that can be individually addressed to create a picture.

^[2] It is important to understand that HDTV isn’t a question of progressive or interlaced scanning but a question of high resolution. Progressive scanning alone doesn’t make a TV signal HDTV. A picture that is displayed in a 480x640 progressive mode is still standard definition (SDTV) while a picture with a resolution of 1,080x1,920 is HDTV even if it uses the old way of interlaced scanning.