Moving Target Velocity Estimation And Imaging Based On PFA Reconstructed Image

Synthetic Aperture Radar(SAR)is an all-day,all-weather high-resolution microwave imaging system.It has an extensive of applications in the military and civil fields.The Polar Formt Algorithm(PFA)is a classical algorithm in the bunch-mode SAR system.The algorithm uses the plane wavefront assumption.In the monostatic PFA,two-dimensional interpolation is used to eliminate the coupling between the distance and the azimuth,eliminate the Range Cell Migration(RCM).And then perform two-dimensional Fourier transform for imaging.In the bistatic PFA,the coordinates are rotated,so that the data is evenly distributed in the parallelogram direction in the range direction and the azimuth direction,and the range re-sampling is performed in the rotated coordinate system,and then two-dimensional Fourier transform is performed for imaging.In the SAR-GMT(Ground Moving Target,GMT)system,due to the introduction of motion parameters,the geometrical positioning error and the azimuth defocusing are widened for the phase term of the monostatic base PFA radar echo data,in order to compensate it.It is necessary to estimate the motion parameters and construct a filter to compensate the radar echo.The azimuth mismatch compression function is constructed in the monostatic PFA,and the motion parameters are estimated by the binary relationship between the motion parameters and the primary term and the quadratic coefficient in the phase term,and the refocus imaging is performed.The relationship between phase term and motion parameter in radar echo data is deduced and analyzed in bistatic PFA,and the azimuth defocus compensation function is constructed.The maximum contrast side of the image is used to estimate the parameters through motion parameter search.The accuracy of motion parameter estimation in monostatic and bistatic PFA is verified by experimental simulation,and the azimuth defocus of refocus imaging is significantly improved.This paper introduces the history and nowadays of SAR development and the research status of SAR moving target system.The motion parameter estimation and refocus imaging of the monostatic and bistatic SAR system are deduced and studied respectively.Among them,in momostatic processing,the echo data needs to perform two 1-dimensional interpolation to eliminate the coupling between the azimuth variable and the range variable.The image error spectrum of GMT is analyzed,and the azimuth mismatch compression function is constructed.The GMT motion parameters are estimated,and the estimated parameters are used for refocus imaging.In order to improve the data utilization of the bistatic PFA,the coordinate system needs to be rotated by an angle.The phase error expression of the moving target in the bistatic PFA reconstructed image is derived and analyzed after the rotated coordinate system.The moving target parameters are searched based on the image maximum contrast criterion and GMT refocus imaging is performed.Finally,through the simulation experiment,the formula derivation and proposed algorithm of this paper are verified.