The SoftWare Radio (SWR) is a technique which is capable of supporting different transmission standards in a single platform. The way of implementing SWR is known as Software Defined Radio (SDR). In Software Defined Radio the basic elements are FFT and Viterbi decoder. Instead of using a separate architecture for the above two sub modules, a common operator technique is used which identifies the common element in FFT and Viterbi algorithms. The similarities can be found by using the butterfly diagrams. The Fast Fourier Transform (FFT) is an efficient algorithm used to compute the Discrete Fourier Transform (DFT) and its inverse. Viterbi decoder is a kind of maximum likelihood decoder used for the decoding of convolutional code.