Noise (video)
3338992
206287864
2008-04-17T17:38:25Z
85.231.106.7
Captialized to titles
[[Image:TV noise.jpg|thumb|250px|right|On an empty channel, an analog TV receiver shows a "snowy" noise pattern.]]
'''Noise''' in analog [[video]] and [[television]] is perceived as a random dot pattern which is superimposed on the picture as a result of [[electronic noise]] and radiated electromagnetic noise picked up by the receiver's [[antenna (radio)|antenna]] – it is the "[[White noise|snow]]" which is seen with poor analog television reception or on [[VHS]] tapes.
When there is no transmission, which is to say no signal, the noise or "snow" is due mostly to [[Johnson-Nyquist noise|thermal noise]] from the device itself, stray electromagnetic fields from other household electric devices, and remnants of the microwave [[cosmic background radiation]] from the [[Big Bang]]<ref>[http://press.princeton.edu/chapters/s7481.html Sample Chapter for Lemonick, M.D.: Echo of the Big Bang<!-- Bot generated title -->]</ref>, all of which is interpreted as [[luma (video)|luminance signal]]. Approximately one-third to one-quarter of such static is residual background radiation from the birth of the cosmos.<ref>[http://www.turnoffyourtv.com/commentary/static.html KYTV - TV Static<!-- Bot generated title -->]</ref>
Due to the algorithmic functioning of a [[digital television]] set's electronic circuitry and the inherent quantization of its screen, the "snow" seen on digital TV is less random, and being almost entirely a product of its own electronics, no cosmic background radiation is displayed.<ref>[http://www.wonderquest.com/fast-answers.htm WonderQuest: Fast answers<!-- Bot generated title -->]</ref>
UK viewers see "snow" on black after sign-off, instead of "bugs" on white, a purely technical artifact due to British receivers using positive rather than the negative video modulation used in Canada and the U.S.
Since one impression of the "snow" is of fast-flickering black bugs on a cool white background, in [[Sweden]] the phenomenon is often called ''Myrornas Krig'', "War of the Ants".{{Fact|date=February 2008}}
==References==
{{reflist|1}}
==See also==
*[[Noise (radio)]]
*[[Interference]]
[[Category:Noise|Video]]
{{tech-stub}}
[[nl:Ruis (televisie)]]
[[ja:スノーノイズ]]
[[sv:Myrornas krig]]