Satellite Navigation Receiver Space-time Interference Suppression Algorithm Research

Since satellite navigation systems have already been used widely in economic and military fields, the ways to improve their anti-jamming capability and reliability become an emergent task. Especially in battle field, electromagnetic interferences are greatly changeable, certainly which raise the urgent question of how to adapt to the remarkable changeability of magnetic interference, and simultaneously to provide effective service. All of this requires us to conduct deep and extensive researches on anti-jamming technologies. The paper just majors in one of anti-jamming technologies of navigation receiver: space-time interference suppressing algorithm.Space-time interference suppressing algorithm results from the fact that navigation receiver has turned out to be incapable of effectively suppressing traditional array signal processing, mainly because the degree of freedom in suppressing wideband interference signals is much greater than that in suppressing narrowband interference. Especially when encountering a large number of wideband interference signals, traditional array signal processing is unable to suppress this interference and will fail to extract expected signals. In order to achieve the best effectiveness of space-time signal processing,the critical issue is to decide which optimization algorithm is the best choice. Different algorithms produce different optimal weights respectively on different criterions. For simulation experiments, 4 space-time interference suppressing algorithms are employed: SMI: Sample Matrix Inversion, MinC: Minimum output power of per satellite under Constrained condition, MinU: Minimum output power of per satellite under Unconstrained condition, and MinMC: Minimum output power of Multi-satellites under Constrained condition.With a deep study on the above-mentioned algorithms and the software MATLAB as the simulation tool, experiments on algorithm simulations are conducted in which parameters for interference signals, expected signals, and noise are set similar to the real environments. By this means, we can evaluate interference capability of each algorithm in the environment of the single wideband interference signal,the narrowband interference signal and complex electromagnetic interference signals. We conclude that under strong interference conditions, the effectiveness descending order of these algorithms is SMI, MinC, MinU,and that under weak interference conditions, MinU is ineffective. Finally, we make comparison between the anti-jamming performances of multi-signals in the environment of the singal wideband and the single narrowband under MinMC. As the angle of interference and expected signals is increasing, the relative anti-jamming performances are all promoted and the promotion degrees are different correspondent to different environments. The evaluation employs SJNR(Signal to Jammer-plus-Noise Ratio) and BER(Bit Error Rate) as the performance criterion.