2025_programme: Coherent Superposition of Sub-aperture Images for Arbitrary Trajectory Synthetic Aperture Sonar Imaging

• Day: June 19, Thursday
    Location / Time: D. CHLOE at 11:20-11:40
• Last minutes changes: Cancelled
• Session: 11. New methods and theories in underwater acoustic imaging
  Organiser(s): Pengfei Zhang, Peng Wang
  Chairperson(s): Pengfei Zhang, Peng Wang
• Lecture: Coherent Superposition of Sub-aperture Images for Arbitrary Trajectory Synthetic Aperture Sonar Imaging
  Paper ID: 2209
  Author(s): Lulu Ren, Shiping Chen, LinZhe Wei, Peng Wang, Pengfei Zhang, Haining Huang
  Presenter: Lulu Ren
  Abstract: When there is a large error between the real motion state and the ideal motion state of the synthetic aperture sonar (SAS), the conventional motion compensation algorithm is ineffective and the imaging model mismatch leads to SAS image defocus. To solve this problem, this study proposes a method to achieve arbitrary trajectory synthetic aperture sonar imaging by coherent superposition of sub-aperture polar images in Cartesian coordinates. First, the sonar echo data were pulsed-compressed and moved to the baseband. Then, the polar sonar image is obtained using single-frame multichannel echo data for real-aperture beamforming. Then the sub-aperture image in the polar coordinate system is resampled to the Cartesian coordinate system. Finally, the imaging results of the different sub-apertures were coherently superimposed in the Cartesian coordinate system to achieve high-resolution imaging. This method has the following advantages: the sub-aperture image is coherently superimposed according to the real position and attitude of the towed body, which is suitable for uneven spatial sampling and nonlinear trajectories ; and the imaging plane is defined as the ground plane, which can eliminate the space-varying effect of motion error and achieve better focusing, and can be applied to wide-beam synthetic aperture sonar motion compensation. The effectiveness of the algorithm is verified by computer simulations and experimental data on the lake, and it can realize synthetic aperture sonar imaging of arbitrary trajectories. At the same time, a fast focusing method based on Fourier transform for polar images with sub-apertures is presented. The computational cost is 1~2 orders of magnitude lower than that of the standard fast backward projection algorithm.
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• Corresponding author: Mr Lulu Ren
  Affiliation: Institute of Acoustics, Chinese Academy of Sciences
  Country: China