基于二阶Keystone变换的FMCW SAR动目标成像与参数估计

Moving target imaging and parameter estimation based on second-order Keystone transform for FMCW SAR

摘要:

本文研究了一种适用于调频连续波（Frequency Modulated Continuous Wave，FMCW）合成孔径雷达（Synthetic Aperture Radar，SAR）的地面动目标成像与参数估计的方法。首先，建立FMCW SAR系统下的动目标回波模型，通过多普勒频移补偿和时频代换，提出了一种基于二阶Keystone变换校正动目标回波距离弯曲的方法。其次，用Hough变换去估计动目标距离向速度，并据此进行距离走动校正。最后，采用Wigner-Hough变换估计动目标的多普勒调频率，通过补偿二次和三次多普勒相位实现动目标的精确聚焦。仿真结果表明：该方法对参数估计有较高的准确性，同时估计的参数对动目标成像有较好的聚焦效果。

Abstract:

In this paper, a method for ground moving target imaging and parameter estimation suitable for frequency modulated continuous wave (FMCW) synthetic aperture radar (SAR) is studied. Firstly, the echo model of moving target under the FMCW SAR system is established. By Doppler shift compensation and time-frequency substitution, a method based on the second-order Keystone transform is proposed to correct the range cell curve of moving target. Secondly, the Hough transform is used to estimate the range velocity of moving target, and the range walk correction is carried out accordingly. Finally, the Wigner-Hough transform is utilized to estimate the Doppler frequency rate of moving target, and compensated the quadratic and cubic Doppler phases, thus achieved accurate focusing of the moving target. The simulation results show that the proposed method has high accuracy in parameter estimation, and the estimated parameters have a good focusing effect on moving target imaging.