Research On Imaging Algorithm For Missile-borne SAR At High Squint

SAR can acquire two-dimensional high-resolution radar images in the observation area,and has great application prospects in the military field.In particular,the missile-borne SAR technology is an important means of achieving precise guidance in modern warfare.Compared with the imaging algorithms of airborne SAR and space-borne SAR,missile-borne SAR imaging algorithm is more difficult and needs to be considered carefully because of its high maneuverability,high squint and high real-time imaging requirements.Moreover,the quality of the images seriously affects the accuracy of the guidance.How to obtain the echo two-dimensional radar image quickly and accurately is the main problem faced by the missile-borne SAR imaging algorithm.In this paper,according to the motion characteristics of missile-borne SAR,the SAR imaging and motion compensation algorithms for missiles under large scene,high squint and non-uniform conditions are studied.Firstly,the instantaneous slant range model and the radar echo model under squint conditions are analyzed in detail,and the distribution and variation of each order component under Taylor's expansion under different parameters are studied.The error distribution of the traditional RDA compared with the RMA in the process of using the approximation is studied,and the applicable range of the algorithm is studied.It was verified by simulation and actual measurement under the positive side view.Secondly,the problem that FSA is not applicable at high squint is introduced,and it is solved by adjusting the FS scaling factor.The key steps of the large squint imaging algorithm using equivalent positive side processing – LRWC and the resulting problems and solutions are analyzed.An ANLCS in dechirp receiving mode is proposed.The effects of different precision processing in distance and azimuth are analyzed by simulation and actual measurement.An imaging algorithm under large scene conditions is proposed.The method of doppler sharpening and sub-beam image superposition is used to solve the problem that the traditional algorithm can not be applied to large scenes,and it is verified by the measured data of large squint large scene.Finally,the components of the slant range error under non-ideal motion are analyzed,and the corresponding compensation methods are given according to the characteristics of each part.The principle of PGA is analyzed.According to the algorithm,the characteristics of non-cavitation error can be processed.The applicability of the high squint non-ideal condition is analyzed according to the actual conditions,and the simulation analysis and actual verification are carried out.