Electrical Noise

Abstract

Any electrical signal that makes recovery of the information signal more difficult is considered noise. For example, ``white snow'' on a TV picture and ``hum'' in an audio signal are typical electrical noise manifestations. Noise mainly affects receiving systems, where it sets the minimum signal level that it is possible to recover before it becomes swamped by the noise. It is important to note that amplifying a signal already mixed with noise does not help the signal recovery process at all. Once it enters the amplifier, noise is also amplified, which is to say that the ratio of S/N power does not improve and that is what matters. When the power of the noise signal becomes too large relative to the power of the information signal, information content may be irreversibly lost. In this chapter, we study the basic classification of noise sources and methods for evaluation of noise effects.