Focusing Wide Bandwidth and Wide Swath Synthetic Aperture Sonar Data Using Modified Nonlinear Chirp-Scaling Imaging Algorithm

摘要

To solve the Synthetic Aperture Sonar (SAS) imaging problem with a wide bandwidth transmitted signal and a wide swath, a novel modified Nonlinear Chirp-Scaling (NCS) imaging algorithm is proposed. The first key step is to reduce the phase error by preserving the fourth order of the Taylor expansion for two-dimensional spectrum. To compensate the high order phase error sufficiently, the second key step is to derive a series of more exact relational parameters resulted from the third and fourth phase filtering and NCS operation by considering the change of linear and second nonlinear for equation frequency modulation slant rate. This operation increases the wide of swath for SAS with a wide bandwidth transmitted signal. The results of simulation show the accuracy and validity of the proposed modified NCS algorithm.