HIGH DEFINITION TELEVISION

HDTV has been talked about for years. One of the reasons the FCC mandated the change to digital is to force HDTV into existence. HDTV is an improvement in picture and sound quality. Instead of about 400 lines of resolution, it is possible to receive 1080 lines. This will allow for larger screen sizes and improved clarity.

HDTV has also adopted Dolby Digital encoding for the sound. The third improvement of HDTV is a wide aspect ratio to present home video in the same ratio as it is in the theater.

Now the confusing part. There are 18 different DTV formats. Six are high definition and 12 are standard definition. There are different resolutions of DTV; the important ones are 480, 720 and 1080 lines of horizontal resolution. Got that?

Next, there are two different ways to display a video image. One is called interlaced (which the industry abbreviates with an 'i') and the other is progressive ('p'). Interlaced shows half of a picture at a time, first the odd lines and than the even lines. By showing these frames at a fast rate, our brain puts the two together into one image (just like animation).

Progressive shows an entire frame at once. The advantage of interlaced technology is there is less information to send at one time. The problem with interlaced technology is motion. When an object has moved between the odd frame and the even frame we see a blurring of the image.

Finally, to compound the problem even more is the number of frames per second that are transmitted. The more frames per second the better the picture, especially where motion is concerned.

So when you add up the different types of resolutions, interlaced or progressive, with different frame rates you end up with 18 formats.

Ok, so lets get real for a moment. Who needs 18 formats; why not just have the best one? Because broadcasters what to increase their profits. They could either show one great picture or show multiple 'channels' of a lower quality picture and sell more advertising space, and we'll throw in interactive TV while we're at it.

What this means is that prime time will probably be broadcast in 1080i. Great picture for when we watch TV most. The rest of the time will be broadcast in either 480i or 720p.

What does "Digital Ready" mean? Currently whatever the manufacturer wants it to mean. What it should stand for is a TV which can accept an outboard digital tuner and be able to display at least 480p. All HDTV ready sets must be digital ready, but not the other way around.

Digital TVs will still be able to hook up to existing video sources. You will still be able to play back home videos and play video games. Most sets should be able to improve the picture of these sources through their converters.