Performance of Direct-Sequence Spread-Spectrum Receiver Using Decision Feedback and Transversal Filters for Combatting Narrowband Interference

Direct-sequence spread-spectrum (DSSS) receiver using both decision feedback (DFB) and twosided transversal filters for combatting narrowband interference (NBI) is proposed. The receiver is made up of two branches. In the first branch, the conventional demodulator is followed by a DFB filter, while in the second auxiliary branch, a demodulator with the carrier in quadrature is followed by a two-sided adaptive transversal (AT) filter. Performance of this receiver has been analyzed on the basis of the calculated mean-square error and the probability of error at the output of the receiver. Special attention was paid to the effects caused by the propagation of errors in the DFB filter. The results obtained show that NBI rejection is fairly high, and practically does not depend upon the difference of frequencies of the desired and interfering carriers nor upon the interfering carrier level.