Alternative Method for SSB Signal Generation

Abstract

This paper presents an alternative scheme for generation of single sideband (SSB) signal. The proposed scheme is a combination of frequency discrimination method and phase discrimination method with emphasis on simplifying the filter design. Modified version of the given message signal is created by selecting the portion of the frequency translated version of the original message signal (the spectrum is shifted by an amount equal to the sum of the lowest and highest frequency components present in the message signal) that lies within the bandwidth of the original message signal. The modified version of the signal is scaled and given a phase shift of 180° and translated in frequency by the desired amount (depends on which sideband is to be eliminated). This version is added to the frequency shifted (equal to carrier frequency) version of the given message signal thereby canceling the undesired sideband. However, filtering is needed to eliminate the other sideband associated with the frequency shifted modified version of the message signal. The filter design is simple as the ratio of the centre frequency to the frequency gap between desired sideband and undesired sideband is relatively larger. The proposed method requires 180° phase shifter and a bandpass filter whose designs are much simpler than those in the conventional case. The mathematical analysis of the proposed scheme along with simulation results has been proposed.