A new direct sequence spread spectrum receiver using decisionfeedback and transversal filters for rejection of the narrow-bandinterference and errors caused by signal distortion

摘要

An improved version of the receiver described by Stojanovic et al.(see Proc. IEEE MELECON Conf., 1987) is proposed. This version offersmuch better narrowband interference (NBI) rejection in direct-sequencespread-spectrum systems. The two-sided adaptive transversal filter (ATF)was replaced by a decision feedback (DFB) ATF in order to reducedistortion of the desired signal. This resulted in a greater immunity ofthe receiver against the NBI. Besides the conventional demodulator, anadditional branch containing the carrier in quadrature and a two-sidedATF is built into the receiver. Performance analysis of the receiver wasbased on the calculation of the probability of error. Special attentionwas paid to the effects caused by the propagation of errors. The resultsobtained show that the NBI rejection is fairly high and practically doesnot depend upon the difference of frequencies of the desired andinterfering carriers or upon the interfering carrier level