What is HDTV?

HDTV stands for High Definition Television, and if you live in the USA, Australia, Japan, or parts of Europe you may already have experienced it.

There are three key differences between HDTV and what's become known as standard definition TV ie regular NTSC, PAL or SECAM. The three differences are; an increase in picture resolution, 16:9 widescreen as standard, and the ability to support multi-channel audio such as Dolby Digital.

The most important aspect of HDTV, and the one which gives it its name is the increased resolution. Old-fashioned NTSC broadcasts have 525 horizontal lines; PAL broadcasts are slightly better at 625 lines. However, not all of the lines are actually used to display the picture, those lines that do display picture information are called active lines. NTSC has 486 active lines and PAL, 576 active lines. In addition, both PAL and NTSC systems are interlaced, that is, each frame is spit into two fields, one field is the odd-numbered lines and the other is the even lines. Each frame is displayed alternately and our brain puts them together to create a complete image of each frame. This has an adverse affect on picture quality.

HDTV is broadcast in one of two formats; 720p and 1080i. The numbers refer to the number of lines of vertical resolution and the letters refer to whether the signal is progressive scan, 'p', or interlaced, 'i'. Progressive scan means that each frame is shown in its entirety, rather than being split into fields. Both systems are significantly better quality than either PAL or NTSC broadcasts.

HDTV uses 16:9 widescreen as is its aspect ratio so widescreen pictures are transmitted properly and not letterboxed or panned and scanned. Dolby Digital multichannel sound can be broadcast as part of an HDTV signal, so if you have a surround sound speaker set-up you can use it to listen to TV rather than just DVDs.

To receive an HDTV broadcast you need either a TV with a built-in HDTV tuner, like this Panasonic plasma HDTV, an HDTV receiver which can pick-up off the air HDTV channels, cable HDTV, or satellite HDTV receiver like Dish Network HDTV and this DirecTV H10 receiver. You also need to live in are where HDTV channels are broadcast or distributed by cable or satellite.

To find out more, read part 2.