Interference suppression in DSSS communication systems using instantaneous frequency estimation

In this paper, we consider broadband jammer suppression in direct sequence spread spectrum (DSSS) communication systems. The transmitted signal in DSSS systems occupies a bandwidth much wider than the bandwidth necessary to send the information. Hence these systems are inherently immune to outside interferences or jammers. The performance of DSSS systems can be further improved in terms of immunity to interferences by suppressing the interference prior to despreading and demodulation. Here, we use a time-varying filter that adapts to the instantaneous frequency of the interference signal to suppress broadband jammers in DSSS systems. The IF of the received signal is estimated from an evolutionary spectrum. The performance of our IF estimation and jammer suppression algorithms are presented by means of examples.