一种基于级数反演的机载圆迹环扫SAR成像算法

An Imaging Algorithm for Airborne Circular Scanning SAR Based on the Method of Series Reversion

较之传统的直线条带SAR模式,圆迹环扫SAR作为一种新的成像模式,能够在短时间内对较大的区域进行快速观测。但是由于其特殊的圆弧飞行轨迹的影响,目标回波信号的2维频谱难以有效获得,从而给后续成像处理带来困难。针对这个问题,该文提出一种基于级数反演法的圆迹环扫SAR成像算法。该方法利用多普勒频率的展开式反演出驻相点展开式系数,进而获得信号的2维频谱,从而有效地实现距离脉冲压缩和距离徙动校正。该方法可通过对两个级数展开式阶数的选取自由控制频谱的精度,利于成像分析及后续处理。最后,点目标的仿真对比结果表明该算法的有效性。

Compared with the traditional strip map mode, as a new imaging mode, Circular Scanning SAR （CSSAR） can be used to perform imaging with a wider area in a shorter time. However, due to the influence of the circular orbit, it is difficult to obtain the two-dimension spectrum of the target echo signal which brings a lot of obstacles to the following imaging processing. Thus, a new method for CSSAR imaging based on series reversion is proposed in this paper. By unfolding the Doppler frequency, the stationary phase point expansion coefficients are obtained, making it easy to access the signal＇s two-dimension spectrum, through which range compression and range cell migration correction can be implemented effectively. Furthermore, the accuracy of the spectrum is controlled by keeping enough terms in the two series expansions, which is helpful to the imaging analysis and the following processing. Finally, the feasibility of the proposed approach is validated with the point target simulations and the comparison results.