Abstract: 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.

Key words: chirp modulation, fast factorized, fast back projection algorithm, SAR imaging