Q. What do you mean by interference?

An information-bearing signal often becomes contaminated by externally generated interference and noise and/or by internally generated noise. The demodulated message signal is generally degraded to some extent by the presence of these distortions (attenuation, interference, and noise) in the received signal. The fidelity of the received message signal is then a function of the type of modulation, the strength of the additive noise, the type and strength of any other additive interference, and the type of any nonadditive interference or noise. This section only introduces some of the major causes of interference and noise, and touches upon some methods of dealing with their effects in order to minimize the interference and suppress the noise.