Research On Anti-jamming Technique Of Navigation Receiver Based On Array Space-time Processing

With the comprehensive completion and rapid development of China's Beidou Satellite Navigation System,people have put forward higher requirements for the accuracy and reliability of navigation and location services.Due to the increasingly complex space electromagnetic environment and the widespread existence of various types of interference,the interference problem has become increasingly prominent,which has severely restricted the application field and application scope of satellite navigation systems.How to maintain the reliable operation of the system in the interference environment and achieve high-precision positioning has become a hot topic in the field of satellite navigation.Aiming at the narrow-band and wide-band interference suppression problems in typical scenarios,the thesis focuses on the anti-jamming technology of navigation receivers based on array space-time processing.Aiming at the problems of the existing array filtering algorithms in terms of interference suppression and impact on positioning accuracy,corresponding improved algorithms are proposed to improve the anti-interference performance of the receiver and the location service capability in special scenarios.The main work and innovations of the thesis are as follows:1.The effect of blind adaptive zero-breaking processing on the phase and delay stability of useful signals is studied.Aiming at the situation that the signal priori parameters are unknown during the array processing,a typical power inversion algorithm is taken as an example to analyze and explore the anti-interference performance and phase delay accuracy of the blind adaptive processing.The simulation data which similar to the real signal characteristics is used for related simulation.The results show that the blind adaptive algorithm can adaptively identify the direction of interference,and generate deeper nulls in the direction of the interference.Therefore,the accuracy of the carrier phase measurement of the desired signal is greatly reduced,and the delay change amount reaches 0.54?,which has some adverse effects on the navigation and positioning effect of the receiver.2.An improved adaptive power inversion algorithm based on space-time pointing constraints is proposed.Aiming at the distortion of satellite signal and the decline of carrier phase measurement accuracy caused by typical blind adaptive processing,the algorithm establishes the relative position relation between satellite and carrier reference frame by using the solution result of vector tracking,and introduces the directional constraint condition of navigation signal,which alleviates the adverse effect brought by blind adaptive processing.Compared with the typical blind adaptive power inversion algorithm,the improved space-time algorithm reduces the phase delay after beam forming to 9.86×10^-5?,realizing the space-time adaptive processing with better observation accuracy.3.An improved space-time algorithm based on optimal main and sidelobe constraints and interference plus noise covariance matrix reconstruction is proposed.Under the condition that the satellite signal direction and other parameters are known,directly use the Capon algorithm to align the beam to the desired signal for reception.By building a special scene where the number of visible satellites is small and the interference and the desired signal are approaching,the typical Capon algorithm is analyzed.The filtering performance points out the defects of typical algorithms.The improved algorithm is optimized and perfected on the basis of the original model,eliminating the convex redundant side lobes,reducing the width of the main lobe,and making the beam have better directivity.The simulation results show that the improved algorithm can reduce the gain attenuation by 40%,and increase the gain difference between the interference and useful signals from 3.748d B to 12.989d B,greatly enhancing the signal discrimination under special scenes,and confirming that the improved algorithm has better main lobe gain effect and phase delay characteristics.