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HDTV - Understanding High Definition Television

TV sets are changing. Soon they will all be HDTV, which stands for High Definition Television. You need to understand HDTV because the U.S. Government has mandated February 17, 2009 as the final cutoff date for over-the-air analog TV.

Not long ago, the decision to buy a TV was simple – how big was the screen and how much would you pay. Now TVs come in a bewildering array of screen types. There are baffling specifications for aspect ratio and for screen resolution. The rear of the TV has a puzzling array of connectors to complicate this further. The prices for these new TV sets can make one’s head spin.

Screen Type

The sales person at your TV store should be able to explain the pros and cons of the different screen types. But just in case here is a brief comparison.

Comparison of HDTV Screen Types

Aspect Ratio

Aspect ratio is another way of saying screen shape. Aspect ratio and resolution are tied to the video source, not the TV. Most new video content has a widescreen aspect of about 16:9. This means that the ratio of the width of the content to its height is 16 to 9. This approximates a movie theater screen.

Screen Shapes

Not all widescreen content follows this ratio and so when it is displayed black bars appear above and below the picture. Older traditional TV has a 4:3 aspect and when displayed on a wide screen TV will have black bars on either side. Many HDTV models can stretch or magnify the picture to eliminate the bars.

Screen Resolution

Screen resolution determines the sharpness and level of detail in the picture. Traditional analog TV, with an aspect ratio of 4:3, has a 480i resolution with a pixel count of 216,000. More pixels mean a better picture with more content and a sharper image. HDTV has two resolutions 720p (921,600 pixels) and 1080i resolution (2,073,600 pixels). Compared to analog’s 480i, 720p has over 4 times, and 1080i has over 9 times the number of pixels. This is why it is called high definition.

Screen Resolutions

Connectors

Adding to this information overload is the mind-boggling array of HDTV connectors. You should spend more time studying the connectors on the back of the TV than staring at the picture on the front when shopping for an HDTV. Each type of connector has its own pros and cons. There are many different video sources for the HDTV - antenna, cable, satellite, DVD/CD, camcorder, VCR, TiVo/DVR, video game console and a computer. Each of these sends a video signal to the HDTV over one or more types of connectors.

We have created a downloadable Microsoft Excel spreadsheet specially designed to help you calculate your component video connection requirements.
Connector Calculator.

Video Connections