For a function that varying with time s(t) be a continuous function to be sampled, and sampling be performed by measuring the value of continuous function every T seconds, which is called sampling interval. This sampled function is given by S(nT),for integer values of n. Sampling frequency or sampling rate fs is defined as number of samples obtained in one second,fs=1/T. Nyquist sampling theorem provides a descr iption for nominal sampling interval required to avoid aliasing. It may be stated simply as sampling frequency should be at least twice the highest frequency contained in a signal.