基于局部直角坐标和子区域处理的弹载SAR频域成像算法

A Frequency-domain Algorithm Based on Local Cartesian Coordinate and Subregion Processing for Missile-borne SAR Imaging

针对弹载SAR平台非直线轨迹运动和大斜视成像的特点,该文提出一种基于局部直角坐标和子区域处理的频域成像算法。对大斜视成像模式,采用局部直角坐标系建模的方法,使距离走动校正后的方位信号具有更高的近似精度;为精确补偿包络和相位的方位空变,采用子区域成像的方式,可显著提高场景边缘处的聚焦质量;将各子区域图像校正至统一的地面坐标系下,即可得到最终的SAR图像。点目标仿真和实测数据验证了所提算法的有效性。

The missile-borne SAR platform has the characteristics of nonlinear trajectory and high-squint mode. A frequency-domain imaging algorithm based on local Cartesian coordinate and subregion processing is proposed. For high-squint mode, the range model is built in local Cartesian coordinate to match accurately the azimuth signal after range walk correction. To compensate the azimuth-dependent range cell migration and Doppler parameters accurately, the imaging area is divided into several subregions. The final focused image can be obtained when all the subregion images are interpolated uniformly into the ground coordinate. Finally, the point targets simulation and real SAR data verify the effectiveness of the proposed algorithm.