Study On Anti-jamming Algorithm For Satellite Navigation Receiver

At present,the applications of global navigation satellite system(GNSS)are almost ubiquitous.However,GNSS is vulnerable to various interferences because of the vulnerability of GNSS.Therefore,it has tremendous realistic significance to enhance the antiinterference competence of satellite navigation receiver.This thesis mainly studies the anti-jamming technology of powerful jamming based on array antenna.The main work includes:The mitigation technology of linear frequency modulation(LFM),the most common non-stationary interference,has been studied.The traditional interference mitigation methods based on stationary signal have poor effect on LFM interference suppression in navigation receiver.However,LFM signal has the best aggregation in the fractional fourier domain of a certain order.Therefore,suppressing LFM interference in the fractional fourier domain can improve the jamming suppression performance.Firstly,a fractional fourier domain LFM interference mitigation algorithm based on linearly constrained minimum variance(LCMV)criterion is proposed.According to whether the direction of arrival(DOA)of satellite signal is known,it is divided into FRFT-PI algorithm and FRFT-MVDR algorithm.Simulation results validate the effectiveness of FRFT-PI algorithm and FRFT-MVDR algorithm,and they can improve the array output signal-tointerference-plus-noise ratio(SINR).Then,in order to make full use of the aggregation of LFM signal in fractional fourier domain and the distortionless reservation of oblique projection to the desired signal,a fractional fourier domain LFM interference suppression algorithm based on oblique projection(FRFT-OBLIQUE)is proposed.Simulation results depict that FRFT-OBLIQUE algorithm can effectively suppress LFM interference,and the output SINR by the FRFT-OBLIQUE algorithm is better than that of FRFT-MVDR algorithm,space-time oblique projection algorithm and space-time subspace algorithm.The anti-jamming algorithm in high dynamic environment has been studied.Under high dynamic conditions,the null formed by the conventional adaptive zeroing antenna algorithm is too narrow,which is easy to deviate from the jamming DOA,resulting in the failure of interferences suppression.Therefore,a null widening and deepening algorithm based on triangular distribution(T-NWD)is proposed from the perspective of a uniform circular array.Simulation results verify the robustness of T-NWD algorithm in a high dynamic environment.