Research On Robust Interference Suppression Technology For Global Navigation Satellite Systems

The navigation signals received by the Global Navigation Satellite Systems(GNSS)receiving terminals are weak and highly susceptible to intentional or unintentional suppression of interference.The antenna arrays based interference suppression technology is an effective way to solve the effect of suppressing interference.However,the GNSS interference suppression system is affected by factors such as antenna array error,channel amplitude and phase error,and carrier motion error,resulting in antenna arrays steering vector mismatch.Interference suppression performance is weakened.Therefore,research on GNSS robust interference suppression technology has important theoretical research significance and practical application value.In this paper,we focus on GNSS antenna array steering vector mismatch,main beam interference and broadband interference suppression.Research on robust interference suppression technology was carried out.The main research contents and innovative results are as follows:(1)Aiming at the interference suppression performance degradation caused by mismatch of antenna array steering vector and interference of main beam.A robust interference suppression method based on covariance matrix reconstruction is proposed.The real steering vector is estimated by constraining the steering vector error range,and the robust problem is transformed into the convex optimization problem and the quadratic constrained quadratic programming problem to solve the optimal weight vector.The analysis results show that the interference suppression method proposed can improve the robustness of the beamforming under the conditions of low snapshot,high SNR and random error of steering vector.When suppressing the main beam interference,it can alleviate the problems of beam pointing offset,output signal-to-interference-noise ratio decline and sidelobe level rise.(2)Aiming at the problem that GNSS interference suppression algorithm can not obtain maximum gain in the direction of arrival of navigation satellite signal when suppressing interference,a robust GNSS interference suppression method combined with pattern control is proposed and extended to multi-beam GNSS interference suppression method.The adaptive pattern control is used to constraint beam pointing,and the multi-beam pattern steering vector is calculated in real time using the prior knowledge of the inertial navigation platform.The analysis results show that,through the robust GNSS interference suppression method,the array pattern beam can still accurately point to the direction of the navigation satellite signal while suppressing the interference,and has a lower sidelobe level,which It improves the ability of GNSS receiver to solve navigation signals.(3)Aiming at the lack of spatial freedom of traditional antenna-based GNSS interference suppression,a robust GNSS robust interference suppression method based on polarization diversity antenna is proposed.The polarization diversity antenna of the fractal defect structure is used to extract two orthogonal polarization signals of the GNSS signal.Combined with polarization diversity adaptive processing,the dual polarization information of antenna elements is applied to satellite navigation interference suppression technology.The analysis results show that the GNSS robust interference suppression method based on polarization diversity antenna improves the broadband interference suppression capability of the GNSS receiving antenna.In the case of single antenna size and structure,the proposed method can suppress wideband interference.(4)Aiming at the problem of GNSS wideband interference DOA estimation,a method of estimating the direction of arrival of wideband array antenna based on mutated particle filter is proposed.By combining the Gauss-Caucy mutation algorithm to improve the particle filter resampling performance,the direction of arrival estimation can be achieved by tracking the target array manifolds at different frequency points.The analysis results show that the proposed method improves the accuracy of the direction of arrival estimation under the condition of coherent broadband interference signals.The estimation performance is improved under the condition of short snapshot.It provides accurate a priori estimation information for GNSS wideband interference suppression.The a priori information suppresses the GNSS wideband interference signal.(5)Aiming at the problem of received signal distortion caused by GNSS receiving terminal antenna and adaptive array signal processing,a simulation model of signal distortion estimation is established.Different from the evaluation of the array pattern and the output signal to noise ratio,the model is based on the receiver solution results and analyzes the signal distortion of blind beamforming,semi-distorted beamforming and distortion-free beamforming.The pseudorange and position error are measured by considering the incident angle of the interference source and the space-time adaptive processing tap.The influence of signal distortion of different interference suppression methods on the performance of navigation receiver is analyzed,which can provide reference for the selection of interference suppression methods in different interference scenarios.