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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.
The azimuth sampling of multiple-receiver SAS systems is non-uniform, which causes standard wavenumber algorithm (ω-κ) can not be applied to multiple-receiver SAS image reconstruction. Solve the problem, two methods are presented, which can adapt the standard ω-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). Detational analyzes 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 effi ciency but produces degraded images when velocities of the sonar array vary in a large range. By contrast, the NFFT method is capable 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.