How Television Works: Transmission and Reception

    Have you ever been watching your favorite show and find yourself wondering just how television works?  Traditional television broadcasting begins in a television studio where a camera picks up an image to be transmitted.  A device called a sync generator makes sure the camera pickup tube is synchronized with the display tube in the television reciever.  It does this by producing signals which stimulate coils in the camera.  This causes an electronic beam to go through designated motions which scan the image.
    Television uses two kinds of electromagnetic waves:  AM and FM.  Interestingly enough, just four television channels take up more space in the electromagnetic spectrum than AM and FM channels used for radio combined.  In the United states, FM waves are used to transmit audio signals.  The FM waves that are used for television are only one half the size of FM waves which are used for radio channels.  Never the less, these FM channels can carry sound from 10 to 15,00 Hz.  Plus, it has space for subcarriers which are used for sterophonic sound and multi-language transmissions.  AM waves are used to transmit video signals.  For color television transmission, a technique called mulitplexing is used.  It allows color images to be transmitted without a larger channel width.  These waves travel from the studio to a transmitter separately, but simultaneously.   At the transmitter they are modulated separately.  Then, they are combined at the diplexer. The diplexer then sends them as one signal to the antenna.  Now the waves are ready for propagation.

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Last Updated: May 19, 1999
Created by Diana Waxman , Jessica Bureau & Greg Roeberg