Performance of a PN Spread Spectrum Receiver Preceded by an Adaptive Interference Suppression Filter

摘要

The performance of a spread spectrum receiver preceded by an adaptive interference suppression (AIS) filter is determined for various CW jamming signals. An analysis and simulation of an AIS filter, covering the band from 200-300 MHz, implemented with a SAW device is presented. The simulation includes modeling of the SAW device, filter tap weights, Applebaum and power inversion adaptive control algorithms, and filter fabrication and circuitry errors. Both desired and interfering signals are generated in the simulator, passed through the AIS filter, and demodulated by a simulated matched filter. System performance was determined by measuring the improvement in pre-detection signal-to-jammer ratio (SJR) and post-detection signal-to-jammer plus noise ratio (SJNR) provided by the filter, and by computing the AIS filter convergence rate. To validate the AIS filter performance, the following additional simulation data was acquired both before andafter filter adaption: the filter frequency response, the receiver corrrelation response, and the pre-detection signal plus jammer plus noise spectrum.