Coherent backscatter simulation for synthetic aperture sonar

Abstract

COSIM is a coherent backscatter simulator for generic high frequency sonars developed by QinetiQ. This model simulates acoustic backscattering in the time domain from various types of seafloor and targets, in various environmental conditions. The parameters of the model include pulse length and type, sonar characteristics, environmental properties concerning water column and sea surface and physical seafloor properties. In this paper we present descriptions of the various simulation stages, from the seabed generation to the signal simulation. Our main focus in thi paper is the introduction of spatial and temporal fluctuations within the water column and on the seabed and their detrimental effect on synthetic aperture sonar processing. Prior work on seabed clutter (Dugelay and Brothers, Proceedings Oceans 2002) and statistical analysis (Dugelay, Brothers and Heald, 142nd ASA Proceedings) is introduced into the seabed simulation module and initial results on the effect of seabed clutter density are presented. More particularly, the introduction of water column fluctuations is studied: the simulation of realistic fluctuations will be described and the effects on the backscattered signals will be analyzed. Finally, synthetic aperture sonar imaging will be shown in a variety of environmental cases and the image degradation will be compared to the environmental fluctuations.