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Analog TV Transmissions are Partly SSB

July 31st Fact-of-the-Day

A variety analog broadcast television transmission standards and sub-standards exist throughout the world. Most of them specify that most video frequency components are to be transmitted SSB, although the term SSB is rarely mentioned in specifications nor is the term normally used in the television industry, because of the special way SSB is employed. For example, analog broadcast TV transmitters in North America are amplitude modulated, which produces a standard AM DSB signal. However, most of the lower sideband is filtered such that modulating frequencies up to .75 MHz are transmitted DSB, frequencies from .75 to 1.25 MHz are transmitted DSB, but with stronger upper-sideband amplitudes, and frequencies from 1.25 to 4.18 MHz are transmitted SSB. The modified lower sideband is called a vestigial (not fully developed) sideband. The transmission mode is abbreviated VSB. ©2005 Martek, International. All rights reserved.

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