Interference mitigation in spread spectrum using discrete evolutionary and Hough transforms

Jammer excision enhances the interference immunity in direct sequence spread spectrum (DSSS) communications. We propose an instantaneous frequency (IF) estimation method for a jammer composed of chirps, that uses evolutionary spectrum and Hough transform. The estimation requires no parametric representation of the IF and provides a correction by means of dechirping and low-pass filtering. Synthesis of the multicomponent jammer and its excision from the received signal is made possible with excellent results. Localized processing, linearization of the IF estimate, recursive correction, and no problems due to cross-terms in the time-frequency distribution or in the matching of parametric models make the proposed procedure efficient and practical. The performance of the IF estimation and its application in DSSS communications are illustrated