Research On Array Signal Processing Model And Imaging Preprocessing Algorithm For Aperture Synthesis Interferometric Radiometer

Based on the principle of coherent measurement,Aperture Synthesis Interferometric Radiometer achieves high resolution imaging by effectively synthesizing large aperture antenna through sparse arrangement of antenna array.In addition,Aperture Synthesis Radiometer imaging can adopt passive detection imaging mode,which has lower power consumption and better concealment.The brightness temperature image can be obtained by inverse Fourier transform of the measured visibility function in the aperture synthesis imaging system.Therefore,the inverse imaging quality of aperture synthesis imaging system is closely related to the accuracy of measuring visibility function.However,in the actual aperture synthesis imaging system,due to the non-ideal hardware amplitudephase error,sparse distribution of array baseline and other factors,the imaging equivalent array factor sidelobe is high,resulting in a serious decline in the measurement visibility function accuracy,which seriously deteriorates the inverse imaging quality.In view of the above problems,this thesis carries out research on the pre-processing algorithm of aperture synthesis imaging based on visibility function,and the main research contents are as follows:(1)Based on the principle of microwave radiation and interferometry,the basic principle and process of aperture synthesis passive detection imaging are clarified,the reasons leading to the degradation of inverse imaging are analyzed,and the necessity of imaging preprocessing is proved.(2)It is necessary to preprocess the visibility function before inverse imaging.Based on the principle of microwave radiation and interferometry,this thesis introduces the basic principle and process of aperture synthesis passive detection imaging,analyzes the causes of degradation of inverse imaging,and proves the necessity of imaging preprocessing.(3)Based on the traditional method of amplitude-phase error calibration in spatial spectrum estimation,a migration algorithm for amplitude-phase error correction of aperture synthesis is proposed.In order to solve the amplitude-phase error caused by non-ideal aperture synthesis array hardware,active correction and iterative self-calibration are adopted.The active calibration algorithm is simple and accurate.Iterative self-calibration algorithm can realize amplitude and phase error calibration through iterative calculation without external auxiliary source.Simulation results show that the algorithm can solve the problem of imaging deterioration caused by array amplitude and phase error and improve the quality of imaging effectively.(4)Aiming at the high sidelobe of equivalent array factor in aperture synthesis imaging caused by sparse baseline distribution,an image preprocessing algorithm based on array factor remodeling is proposed.An innovative algorithm is proposed which is suitable for both array baseline sparsity and system amplitudephase error,simplifying the visibility function preprocessing process.Simulation results show that the algorithm has a significant inhibitory effect on the high sidelobe of imaging array factors,effectively improves the quality of inversion imaging,and solves the problem of inversion imaging deterioration caused by sparse array baseline and system amplitude and phase error.