Performance analysis of subspace projection techniques for anti-jamming GPS using spatio-temporal interference signatures

Combined spatial and time-frequency signatures of signal arrivals at multi-antenna receivers has been used for effective nonstationary interference suppression in broadband communication platforms. This paper presents a performance analysis of subspace projection array processing techniques for suppression of frequency modulated (FM) jammers in GPS receivers. The FM jammers are instantaneous narrowband and have clear time-frequency ((t-f)) signatures that are distinct from the GPS C/A spread spectrum code. The paper assumes that the spatial signature of the jammer is accurately estimated, but its instantaneous frequency (IF) estimate, which provides the basis for construction of the jammer subspace exhibits zero-mean independent Gaussian errors. Simulation results comparing the effects of IF errors in a single and multi-antenna GPS receivers are provided.