Research On High-Precision Anti-Jamming Algorithm Of GNSS Array Antenna

With the increasing complexity of the electromagnetic environment and the increasing number of interfering signal types,the requirements of GNSS receivers for anti-jamming capability are gradually increasing.From time domain,frequency domain,air domain to airtime domain,different types of adaptive anti-jamming algorithms are proposed to effectively suppress the existing broadband and narrowband interference signals according to the respective characteristics of different signal types.The air-time domain adaptive antiinterference processing algorithm can suppress the interference signal in the side flap well,and expand the freedom of the original array antenna by extending the air domain to air-time domain,so as to eliminate the interference signal in the satellite navigation signal well,thus ensuring the navigation and positioning solution accuracy of the subsequent system,which is the core of the GNSS receiver;the main flap anti-interference algorithm of the array antenna can suppress the interference signal in the main flap well.The main flap of the array antenna can suppress the interference signal in the main flap and eliminate the interference signal in the main flap of the array antenna,so as to provide an important guarantee for the subsequent beam forming algorithm.In order to achieve the effective suppression of interference signals and the subsequent high-precision positioning effect of GNSS receiver,and to improve the antiinterference performance of the whole system,the thesis decided to conduct an in-depth study on the space-time domain adaptive anti-interference processing algorithm and the array antenna main flap anti-interference algorithm.Firstly,the thesis focuses on analyzing the importance of anti-jamming technology of satellite navigation system,then introduces the basic principle of adaptive anti-jamming algorithm,and completes the mathematical modeling of anti-jamming system of array antenna through the basic knowledge of array antenna signal model and the theoretical derivation and analysis of adaptive anti-jamming algorithm and its filtering optimal criterion.Secondly,the paper focuses on the power inversion algorithm and the minimum power distortion-free response(MPDR)algorithm in the air domain and air-time domain,focusing on the suppression effect for broadband interference signals and narrowband interference signals,and for the existing problems in the air domain MPDR algorithm,the guiding vector of the ideal useful signal is added to the existing constraint criterion,and an air-time domain E-MPDR adaptive anti-interference algorithm is proposed.The method is validated through comparative simulation experiments.Thirdly,an improved null-time domain adaptive anti-interference algorithm based on EMPDR is proposed to address the problems that the mutual correlation function is not linearly symmetric and phase distortion bias in the null-time domain E-MPDR adaptive antiinterference algorithm proposed above.By theoretically deriving and analyzing the response function of the air-time domain filter in the inter-correlation function composed of the array output signal and the ideal useful signal,the number of time-delay taps is used as a constraint criterion to reduce the pseudocode phase and carrier phase deviation introduced by the air-time domain E-MPDR adaptive anti-interference algorithm,and the proposed algorithm is verified by comparative simulation and analysis to check the the validity of the proposed algorithm is verified through comparative simulation and analysis.Finally,the main flap anti-interference algorithm of the array antenna is studied,focusing on the case of interference signal in the main flap,and the traditional blocking matrix transformation algorithm is analyzed theoretically.By adding a suitable loading to the diagonal of the matrix,the covariance matrix is transformed into an invertible matrix,which solves the problems of main-wave peak shift and shallow zero trap in the original algorithm;through the theoretical derivation and analysis of the eigenprojection matrix transformation algorithm,an improved eigenprojection matrix transformation algorithm based on covariance reconstruction is proposed for the problem of main-wave peak phase shift after suppressing the main-wave peak interference signal.The main wave peak offset problem introduced by the original algorithm is reduced by replacing the eigenvalues of the main flap interference signal with those of the corresponding eigenvalues,and the practicality and effectiveness of the improved method are further demonstrated by comparing the two traditional algorithms and their improved algorithms.