Research On Anti-jamming About Satellite Navigation Receiver With Adaptive Nulling Antenna

This thesis focuses on the research of anti-jamming techniques of satelite navigation receiver with adaptive nul ing antenna.We start from the interference tolerance of the general receiver,and then we explore the maximum interference tolerance that adaptive spatial notch and beamforming can improve.We analyze the anti-jamming capability of GNSS receiver from two angles.One is the ability to restrain factitious jamming,the other one is the ability to against the harsh environment(such as low SNR environment).In terms of factitious jamming,this thesis analyzes the anti-jamming capability of the satellite navigation receiver with adaptive spatial notch and beamforming antenna array,points out the disadvantages of this method,and proposes an improved design scheme.As for low SNR environment,this thesis analyzes the interference tolerance of the general receiver,points out the existing problems,and proposes the improved algorithm which can improve the capture and tracking performance of the receiver.The main research results of this thesis are as follows:1.The anti-jamming performance of satellite navigation receiver and its simulation test method are investigated.The definition of interference tolerance of GPS receiver is given,and some commonly used measures to improve the anti-jamming capability of satellite navigation receiver are summarized,and the ability of adaptive nul ing antenna to counteract enemy malicious interference is analyzed emphatically.A simulation test method for the antijamming capability of satelite navigation receiver is designed,which can imitate the structure of the real receiver.In order to accurately describe the working state of the receiver under the interference condition,three kinds of interference effect decision criterias are given in this thesis.The interference tolerance of GPS C/A code receiver and P(Y)code receiver under these three criteria is calculated.The anti-jamming test results of both adaptive spatial notch and beamforming array antenna system are given,and the advantages and disadvantages of this method are analyzed.2.Some key techniques of both adaptive spatial notch and beamforming array antenna systems are studied.A filter bank for GPS military code signal and civil code signal is designed.The structure of hierarchical filter down-sampling is adopted.The performance of the filter bank is analyzed in detail and compared with the conventional filter.The results show that the filter bank can reduce the resource consumption while ensuring the performance,and the low delay of signal processing reduces the influence on the subsequent signal processing.A half-bit PMF-FFT acquisition method is proposed for low SNR environment.The acquisition sensitivity of the GPS C/A code receiver is improved,and the tracking loop of the receiver is improved.Two novel phase discriminator algorithms are proposed.The performance simulation results show that both of these algorithms can achieve better carrier synchronization performance.Aiming at some problems in the existing beamforming techniques,an adaptive beamforming method without guidance vector assistance is proposed in this thesis.The results show that,this method can also obtain the spatial diversity gain of array antenna and improve the signal-to-noise ratio(SNR).3.The FPGA design and implementation of some baseband signal processing units in an adaptive nul ing antenna engineering prototype are given.The baseband signal processing units contain high performance filter module,civil code synchronization acquisition module,civil code synchronization and carrier synchronization module,adaptive spatial notch module and adaptive beamforming module,and these modules are compared with the simulation results of MATLAB.