A new direct sequence spread spectrum receiver using decision feedback and transversal filters for rejection of the narrow-band interference and errors caused by signal distortion

An improved version of the receiver described by Stojanovic et al. (see Proc. IEEE MELECON Conf., 1987) is proposed. This version offers much better narrowband interference (NBI) rejection in direct-sequence spread-spectrum systems. The two-sided adaptive transversal filter (ATF) was replaced by a decision feedback (DFB) ATF in order to reduce distortion of the desired signal. This resulted in a greater immunity of the receiver against the NBI. Besides the conventional demodulator, an additional branch containing the carrier in quadrature and a two-sided ATF is built into the receiver. Performance analysis of the receiver was based on the calculation of the probability of error. Special attention was paid to the effects caused by the propagation of errors. The results obtained show that the NBI rejection is fairly high and practically does not depend upon the difference of frequencies of the desired and interfering carriers or upon the interfering carrier level.