How Does
How Does High Definition Television Work?
Analog Television
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Before the digital age, television was broadcast using analog signals. Analog television, developed in the 1940s, operates at specific frequencies (25 to 30 Hz) to send moving pictures with synced sound over the air waves. Pictures and sound are sent by transmitters, much like how radio broadcasts to listeners. Analog television sets capture pictures through a picture tube (cathode ray tube, or CRT). A small device, called an electron gun, moves from frame to frame "painting" the picture on the screen. This creates the illusion of a moving picture (simply stated, a series of very quick still shots).
Digital Televsion Transmission
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With technological advancements since the days of analog transmission, broadcasts are now possible with a much faster and higher quality method of capturing moving pictures and sending them over the air waves. Digital television transmitters send more efficient signals, resulting in clearer pictures than its analog predecessor. Digital transmission is also much faster, able to send about 2.5 megabytes per second, depending on bandwidth. Digital signals are created and sent by computers.
All U.S. television stations, at the direction of the FCC, are currently in the process of converting from analog to digital transmission (see Resources).
High Definition Televsion
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High definition television sets (HDTV) are equipped specifically to operate as digital receptors. Screens on most high definition television sets are made of plasma and contain rows of pixels running up and down the screen. Digital graphics and sound interfaces allow digital transmissions to be displayed and heard almost as quickly as the signals are sent out.
eHow Article: How Does High Definition Television Work?
