Jammer excision in spread spectrum using discrete evolutionary-Hough transform and singular value decomposition

Jammer excision enhances interference immunity in direct sequence spread spectrum (DS-SS) communications. In this paper, we propose an excision procedure, based on the discrete evolutionary and Hough transforms, for jammers composed of arbitrary chirps. The proposed instantaneous frequency (IF) estimation is done locally, without parameters, and it is recursively corrected. A singular value decomposition (SVD) of the dechirped signal allows us to synthesize the jammer locally, and then subtract it from the received signal. Localized processing, linearization of the IF estimate, recursive correction, and no problems due to cross-terms in the time-frequency distribution or in matching IF models make the proposed procedure efficient and practical. Also, SVD provides an efficient way to synthesize the jamming signal. The local IF estimation and the performance of the proposed exciser in DS-SS systems are illustrated.