Research On SAR Tomography Phase Compensation Methord

Synthetic aperture radar tomography is an extension of synthetic aperture radar in space,which solves the problem of cylindrical symmetry blurred in SAR(the same skew scattering point is compressed to a range to azimuth element).The skew and phase error compensation are two important steps in the SAR tomography process.The algorithm of the offset and phase error compensation will produce a large difference in the results of the imaging results of the SAR tomography,so the algorithm of the offset and phase error compensation is studied in this paper.SAR tomography requires the parallel radar flight track at different time.The actual radar flight path does not conform to the ideal conditions.The paper realizes the correction of the orbit by the research of the algorithm.The skew algorithm relies on the acquisition of the center distance between radar and reference terrain.In this paper,the center slant distance is calculated by using the spatial coordinates of radar and reference terrain.The SAR image provides the radar space position coordinates at 12 time points before and after the imaging time.The polynomial fitting method is used to simulate the flight path of the radar,and the location of the radar imaging time is obtained.The distance Doppler equation describes the relationship between the position of the object and the satellite.In this paper,the distance Doppler equation is used to construct an error function to estimate the location of the reference terrain.In this paper,two phase error compensation algorithms are studied for phase gradient autofocus algorithm and permanent scatterer interferometry,taking the spatial intensity correlation of phase error as the breakthrough point.The PGA algorithm is based on the special unit(which contains only one strong scattering element in the distance to azimuth element),and the phase error is estimated by the sum of the difference of the phase error of the explicit unit.The paper studies the distinction and recognition of the explicit unit,and uses the weighted least square estimation method to estimate the phase error difference of the SAR image.The PS-InSAR technique uses the scattering characteristic of the permanent scatterer not to change with the time,and only closes the phase error of the PS point,and uses the interpolated square.The phase error of the entire image is obtained by the formula.Based on the strong correlation of the phase error and the small range of the observation area,the phase error of the SAR image is taken as the phase error of the phase error of the PS point,and the estimation of the phase error of the SAR image is realized.In this paper,the SAR image sequence of Erlang mountain area in Sichuan province is used to carry out experiments,and the algorithm is verified.Two phase error compensation algorithms studied in this paper are used to compensate the phase error of the SAR image sequence after the deviation,and use the three existing SAR tomography algorithms to compare and analyze the imaging results of the SAR image sequence before and after the phase error compensation,and compare the imaging results with the actual data,and the results show that the image results are compared with the actual data.The phase error compensation algorithm based on PGA is more universal.