Autonomous assessment of seabed ripple geometry from bistatic acoustic scattering data

Abstract

One of the greatest sources of interference in the acoustic scattered fields from seabed targets is bottom scattering. Directional sand ripples in particular produce three-dimensional scattering radiation patterns when insonified that distort measured scattering fields from aspect-dependent targets. These bistatic scattered fields are impacted by the topography of the ripple field, such as anisotropic angle relative to the acoustic source and ripple geometry. This paper describes a method for estimation of sand ripple field parameters with data from Autonomous Underwater Vehicle (AUV) sampling of the bistatic scattered acoustic field that results from insonification of the seabed with a fixed acoustic source. Background on sand ripple scattering is first reviewed and simulation results are shown illustrating differences in scattered field results based on various parameters. The Support Vector Machine (SVM) regression methodology used for parameter estimation is then presented. Finally, the results for estimation of anisotropy angle, height and major correlation length are described based on simulation and the conclusions and suggestions for future work are stated.