Multi-Static Active Acoustics

The main thrusts of this effort are to develop a fundamental understanding of the coastal acoustic environment, and to develop new numerical models of the 3D scattering by completely or partially buried seabed objects, with the objective of developing new sonar concepts for improved detection and classification of targets such as mines and hazardous-waste containers.

Other critical components of this study are the associated scattering and reverberation from the seabed itself. Detection and classification of buried objects are extremely difficult with existing sonar systems because of the very limited bottom penetration achieved at the high frequencies used in traditional sonars. Lower-frequency systems have reduced-resolution capabilities and, therefore, have not been seriously considered in the past, in spite of their improved bottom penetration.The hypothesis being pursued at present is that instead of using high-resolution acoustic imaging for classification, the target can be classified by the spatial and temporal characteristics of its full three-dimensional scattered field at the lower frequencies needed for bottom penetration. Thus, if this is the case, the seabed may be insonified from one platform, e.g., an AUV, and measured from one or more separate platforms (multi-static sonar configuration), and pattern recognition techniques may be used to detect and identify unique scattering characteristics. As such, this project is a characteristic example of how the Ocean Engineering Department is pursuing new and nontraditional sensor technology for AUV networks such as the AOSN.