Fast factorized back-projection for circular synthetic aperture sonar imaging

Circular synthetic aperture sonar (CSAS) has attracted great attention in the field of high-resolution SAS imaging. Time domain circular synthetic aperture imaging algorithm can adapt the non-uniform sampling on azimuth direction caused by platform non-uniform velocity, it has the advantage of lower memory demand and suitable for parallel computation. However, exact time domain demands huge computation resources. The Fast Factorized Back-Projection (FFBP) time domain imaging algorithms can reduce the computation load dramatically. In this work, the FFBP imaging algorithm has been used in circular SAS trajectories for experiment data. The first step is to split the entire aperture into several subapertures, then, processing the data in sub-apertures with back-projection method. The last step is to obtain the full-aperture CSAS image by merging all sub-images obtained from the sub-aperture processing. The experiment results have been validated the FFBP imaging algorithm compare with reference simulation result. What’s more, the result also shows that the FFBP imaging quality decrease with the approximation error of FFBP increased.