A new algorithm for high-precision submarine topography imaging

730-738In this paper, a new algorithm for high-precision submarine topography imaging is proposed. The innovative idea comes from the most effective and widely used instruments: Multibeam echo sounder (MBES) and side scan sonar (SSS). The MBES can acquire bathymetric information with high precision, but its along-track resolution is related to the result of the beam angle multiplied by the slant range. The SSS combined with synthetic aperture sonar technology can achieve a high-precision along-track imaging resolution, but it cannot acquire bathymetric information directly below it. The proposed algorithm uses the beam footprints of the MBES in the along-track direction to perform the aperture synthesis and uses the time-domain and beam-domain imaging algorithms to acquire high-precision along-track imaging resolution and bathymetric information, to improve the along-track resolution and obtain the bathymetric information with high precision at the same time. Finally, an experiment is performed to evaluate the effectiveness of our method. Experimental results demonstrate that two targets, 13 cm in size, can be clearly observed from the obtained imaging. Moreover, their bathymetric information can be calculated by using the beamforming angle information

A Method for Estimating Dominant Acoustic Backscatter Mechanism of Water-Seabed Interface via Relative Entropy Estimation

It is important to distinguish the dominant mechanism of seabed acoustic scattering for the quantitative inversion of seabed parameters. An identification scheme is proposed based on Bayesian inversion with the relative entropy used to estimate dominant acoustic backscatter mechanism. DiffeRential Evolution Adaptive Metropolis is used to obtain samples from posterior probability density in Bayesian inversion. Three mechanisms for seabed scattering are considered: scattering from a rough water-seabed interface, scattering from volume heterogeneities, and mixed scattering from both interface roughness and volume heterogeneities. Roughness scattering and volume scattering are modelled based on Fluid Theories using Small-Slope Approximation and Small-Perturbation Fluid Approximation, respectively. The identification scheme is applied to three simulated observation data sets. The results indicate that the scheme is promising and appears capable of distinguishing sediment volume from interface roughness scattering and can correctly identify the dominant acoustic backscatter mechanism