Inversion of High Frequency Acoustic Data for Sediment Properties Needed for the Detection and Classification of UXOs
An essential component in the detection and characterization of underwater munitions is knowledge of the acoustic response of the environment as well as the environment's effect on the acoustic response of munitions. Simulation tools and technologies have been developed under SERDP-funded research initiatives, such as the Personal Computer Shallow Water Acoustic Toolset (PC SWAT), to model the acoustics of both the environment and the munitions. The evaluation of these technologies, as well as their future use in unexploded ordnance (UXO) remediation, relies on knowledge of the underwater environment, particularly the properties of the seafloor. Conventional methods for determining relevant seabed properties employ time-consuming point measurements. Commercially available high-frequency multibeam echo sounders (MBESs) may offer a solution to this problem by making faster measurements over larger areas. While these systems are primarily intended for high-resolution bathymetry, acoustic inversion techniques can be used to estimate seafloor parameters relevant to the UXO problem.
The objective of this research is to develop and rigorously test a physics-based algorithm that can invert high-frequency acoustic data for sediment parameters. This research will result in new algorithms for high frequency acoustic data inversions and system- independent environmental assessment in terms of measurable seabed parameters, which can then be used as inputs to acoustic and electromagnetic systems.
The inversion algorithms developed in this project will incorporate the results of recent research in high-frequency sediment acoustics, utilizing models and technologies that have been developed through Office of Naval Research (ONR)-funded experiments. Acoustic data will be collected with high-frequency acoustic systems in both sand and mud environments. The accuracy of the inversion algorithms applied to this data will be evaluated using environmental measurements collected at the experiment sites.
As high-frequency sonar systems begin to be applied to the detection and classification of UXO, the algorithms and techniques developed in this project will allow these same systems to determine the sediment properties as well, thus reducing efforts and costs in wide-area surveys. Scientific questions also remain in understanding the spatial variability of seafloor properties and their influence on the sound propagation, particularly in the shallow water environment. These techniques would provide a tool to assess this variability rapidly over larger ranges then is currently available. (Anticipated Project Completion - 2015)
Points of Contact
Dr. Brian Hefner
University of Washington
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