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

The azimuth sampling of multiple-receiver SAS systems is non-uniform,which causes standard wavenumber algorithm（ω—κ） can＇t be applied to multiple-receiver SAS image reconstruction.To solve the problem,two methods are presented,which can adapt the standardω—κalgorithm to multiple-receiver SAS system.One method named Non-uniform Separate Fourier Transform（NSFFT） converts the Fourier Transform（FT） of the non-uniform samples 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 azimuth non-uniform sampling FT by non-uniform fast FT（NFFT）.Detail analyses are presented on two methods＇ theoretical principles.For validation,both methods are applied to reconstruct images of simulation datasets and 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 degraded 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.