Research on non-uniform sampling problem when adapting wave number algorithm to multiple-receiver synthetic aperture sonar

The azimuth sampling of multiple-receiver SAS(Synthetic Aperture Sonar) system is non-uniform,which causes standard wavenumber algorithm(ω-k) can't be applied to multiple-receiver SAS image reconstruction.To solve the problem,two methods are presented,which can adapt the standard ω-k algorithm to multiple-receiver SAS system. One method named Non-uniform Separate Fourier Transform(NSFFT) converts the Fourier Transform(FT) of the non-uniform sampling in azimuth direction into several uniform FTs on the assumption that the sonar array moves along a linear track in a uniform velocity.The other method,however,calculates the FT of non-uniform sampling by non-uniform fast FT(NFFT).Detail analysis is presented on two methods' theoretical principles.For validation,both methods are applied to reconstruct images of the simulation datasets and the lake-trial datasets.Results show that both methods can be applied to image reconstruction of multiple-receiver SAS.The NSFFT method has the advantage of higher computing efficiency but produces lower quality images when velocities of the sonar array vary in a large range. By contrast,the NFFT method is able to deal with arbitrary-velocity variation but has a heavier computing load.In conclusion,both methods have pros and cons,and the choice of two methods is determined by the application situation.