BP算法的低效极大地限制了其在大范围场景和实时性要求高的场合下的应用。利用空间上相邻的点存在近似相等的"等效距离"原理，基于已有的两类快速BP算法，提出一种基于方位调制的快速分解因子BP算法。一方面利用基于方位调制的BP算法减少等效合成孔径长度，另一方面利用快速分解因子BP算法减少合成孔径范围内孔径点数。该算法在已有的快速BP算法基础上进一步提高效率，且能够并行实现，在机载实时成像和卫星在轨实时成像方面有一定的应用潜力。仿真和实测数据验证了该算法的有效性。
The inefficiency of the BP algorithm greatly limits its application in wide range scenarios and occasions of high real-time requirements. In this work, we propose a fast factorized back-projection approach based on chirp modulation, which combines the two kinds of fast BP algorithms based on the concept of the equivalent distance. On one hand, the proposed algorithm reduces the length of equivalent synthetic aperture by the chirp modulated back projection (CMBP) algorithm. On the other hand, the proposed algorithm reduces the number of synthetic aperture by the fast factorized back projection (FFBP) algorithm. We argue that the physical meaning of the polar angle of the equivalent distance remains the same, and points within a range of pixel space still have approximately equal equivalent distances. Therefore, the FFBP algorithm can be realized through the equivalent distance. Simulation and experimental data validate the effectiveness of the algorithm.
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