Median-prefiltering-based robust acquisition of direct-sequence spread-spectrum signals in wide-band pulse jamming

We propose robust acquisition schemes for chip time-synchronous direct-sequence spread-spectrum (DS/SS) signals in wide-band pulse jamming. To mitigate the performance degradation due to the impulse-like wide-band jamming signal, the received signal is preprocessed by employing simple order statistic filters. We consider the use of two types of median filtering schemes: a running median filter operating at a chip rate and a block median filter processing the received signal sampled at an oversampling rate. For analytic design, the partial correlation of median filtered pseudonoise (PN) signals is approximated by a piecewise linear model using an upper bound. The analytic design is verified by computer simulation. Finally, the acquisition performance of the proposed schemes is compared to that of conventional schemes.