The chapter begins with identifying common sources of noise affecting electrical communication. The discussion on frequency domain representation of noise is followed by the effect of different types of filtering on noise that includes differentiation and integration. In superposition of noise, mixing of noise with sinusoid and another noise source is discussed. It is shown that representation of noise by quadrature components is helpful in characterizing narrowband noise. Various issue related to it including power spectral density, probability density etc. are discussed. Representing noise in terms of orthonormal components help in identifying irrelevant noise components. This issue is discussed with an example and a correlator scheme. Throughout the discussions reference to white noise is made which is most common type of noise that interferes with signal in electrical communication.
