CAJ | 학술논문

对于合成孔径雷达(SAR)成像来说，后向投影(Back Projection, BP)算法是一种十分重要的时域成像方法。然而现有的自聚焦算法都是基于频域成像算法开发的，无法直接用于BP聚焦图像的误差相位估计。针对这一问题，该文提出一种适用于BP图像的自聚焦算法。该算法以图像锐度函数为目标函数，以待估计的相位校正值为自变量，通过坐标下降最优化算法循环迭代获得它们的最优估计。在问题求解中，该算法利用勒让德多项式来拟合目标函数，使得每次迭代的最优解可以解析地获得，避免了低效的线搜索过程。基于仿真数据和实测数据的实验验证了该算法的精确性和有效性。
대우합성공경뢰체(SAR)성상래설，후향투영(Back Projection, BP)산법시일충십분중요적시역성상방법。연이현유적자취초산법도시기우빈역성상산법개발적，무법직접용우BP취초도상적오차상위고계。침대저일문제，해문제출일충괄용우BP도상적자취초산법。해산법이도상예도함수위목표함수，이대고계적상위교정치위자변량，통과좌표하강최우화산법순배질대획득타문적최우고계。재문제구해중，해산법이용륵양덕다항식래의합목표함수，사득매차질대적최우해가이해석지획득，피면료저효적선수색과정。기우방진수거화실측수거적실험험증료해산법적정학성화유효성。
The Back Projection (BP) algorithm is a very important time-domain methodology for Synthetic Aperture Radar (SAR) imaging. However, conventional autofocus techniques are based on frequency-domain imaging algorithms, and can not be directly applied to BP imagery for error phase estimation. In this paper, an autofocus algorithm for BP imagery is proposed. The algorithm takes image sharpness as an objective function, and employs the coordinate descent optimization scheme to obtain the optimum phase-corrected variables by iterations. In the implementation, with a Legendre approximation of the objective function, the optimal phase estimation can be found analytically for each parameter within an iteration, avoiding computationally expensive line-search procedures. The experimental results with both simulated and measured data confirm the accuracy and effectiveness of the proposed algorithm.