HDTV stands for High Definition Television.  Digital TV broadcasting has several levels of quality, and HDTV is the highest level.  All HDTV televisions are digital, but not all digital televisions can reproduce HDTV.  So, in order to watch HD programming you will need a TV set that is HD enabled.


The following is a brief lesson on the various levels of digital television:

The ATSC identified 18 formats of digital television, giving flexibility both to broadcasters and consumers.  The 18 formats fall within three key levels of digital television. They are, from lowest level to highest:  "Standard Definition TV" (SDTV), "Enhanced Definition TV (EDTV), and "High Definition TV" (HDTV). You can think of the levels as Good-Better-Best.


SDTV: Better Than Regular TV

Standard Definition TV broadcasting has eliminated those annoying "ghost" images and "snow" sometimes seen in analog broadcasts. SDTV's picture resolution can range from about the same as analog TV to about twice the resolution-a noticeable improvement. The audio is digital, too, so the sound is of higher quality than on analog TV (like a CD compared to FM radio) and can even feature multiple channels of surround sound.


EDTV: Really getting good

The next level of digital television is Enhanced Definition TV, EDTV. EDTV features a minimum of 480p scanning lines, for a more detailed picture than SDTV. You can see the difference. EDTV also can reproduce Dolby® Digital audio.


HDTV: the best you can get


HDTV has all the benefits of EDTV, but goes far beyond it in picture resolution and audio features. The HDTV specification requires a minimum of 1080i or 720p scanning lines, far higher than EDTV and about five times the resolution as analog TV! It's a level of detail that you've never seen before.

1080i and 720p


How do 1080i and 720p compare? 1080i actually has higher resolution than 720p, but doesn't render motion quite as well. 720p-with its progressive scanning-delivers smoother motion (especially important for fast-moving action, such as in sports) but has a lower resolution than 1080i. It still has great resolution, but lower. (Don't worry; any HDTV receiver can receive both formats, and a true HDTV television can display both formats.)


Pixels


Another way to compare the two is by looking at their pixel count (pixel is short for "picture elements", the individually addressable areas of light and shadow on your screen). The 720p format creates an image with 720 lines, each with 1280 pixels, so it has a resolution of 1280 x 720. The 1080i format creates an image with 1080 lines, each with 1920 pixels, so its resolution is a higher 1920 x 1080. Denser pixels = a better picture.


When you're shopping for a new TV, remember this: at a minimum, an HDTV television-whether it's a projection television, plasma display, or traditional CRT type-must be able to display images at a minimum of 1080i or 720p. A "digital TV" or "digital-ready TV" or "EDTV-ready TV" that doesn't meet this spec cannot deliver HDTV! You would still get the improvement of digital TV over analog, but you wouldn't be ready for HDTV, which is the future of broadcasting.


The Hardware You'll Need for HDTV


HDTV is now being offered via satellite (like on DirecTV and others), via cable (like Time Warner, Adelphia, and Comcast), and via over-the-air broadcasts from NBC and other networks.


In order to receive and display HDTV, you'll need:

A subscription to a satellite or cable TV provider, or an over-the-air antenna, to bring the HDTV signal into your home.
An HDTV tuner or set-top box, to decode and distribute the signal.
A true HDTV monitor, to display the signal.
And, it's not absolutely required, but to get the most out of HDTV you should have a good surround sound system. 


There are several configurations that will work, depending upon where you live and your access to cable, satellite, and over-the-air signals. Also, some HDTV televisions have built-in tuners, so you would just connect this television to your HDTV source (such as your satellite feed) and you're ready.

A good first step is to call your local cable or satellite provider (or go onto their web site) and find out about their HDTV services in your area. You can find their phone number on your monthly statement. Ask which type of HDTV-capable set-top box or decoder you will need-you may already have it.