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White Noise

October 14th Fact-of-the-Day

The power spectrum of white noise is frequency-independent. Noise with a flat power spectrum has many applications. For example, if white noise is applied to filter, the noise power spectrum in the filter output will have the shape of the filter's frequency response. White noise can be used to measure the Noise Figure of a receiver by gradually increasing its amplitude at the antenna terminals until the receiver output noise just starts to increase, at which point the added white noise will be approximately equal in amplitude to the receiver's internal noise. However, despite all the applications and frequent references to white noise, white noise is a bit of a 'white lie,' because it doesn't actually exist in reality. The so called 'white noise' that exists is noise that is flat over only some finite frequency range, and therefore, by definition, is not actually white noise. ©2004 Martek International All rights reserved.

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