LIU Wei  LIU Jiyuan  ZHANG Chunhua

(Institute of Acoustics, Chinese Academy of Science  Beijing  100190)

Received Feb. 27, 2009

Revised Mar. 20, 2009

Abstract The azimuth sampling of multiple-receiver SAS systems is non-uniform, which causes standard wavenumber algorithm (w - k) can’t be applied to multiple-receiver SAS image reconstruction. To solve the problem, two methods are presented, which can adapt the standard w – 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 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, calculated 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-velocities 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.　　　

PACS numbers: 43.30, 43.60