Demonstration of Physics-based Inversions of Multibeam Echosounder for Sediment Properties

Brian Hefner | University of Washington

MR18-1406

Objective

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 [1]. Simulation tools and technologies have been developed under SERDP‐funded research initiatives, such as the Personal Computer Shallow Water Acoustic Toolset (PC SWAT) [2], to model the acoustics of both the environment and the munitions. The evaluation of these technologies, as well as their future use in unexploded ordinance (UXO) remediation, rely on knowledge of the underwater environment, particularly the properties of the seafloor. Commercially available high‐frequency multi‐beam echo sounders (MBESs) may offer a solution to this problem by making faster measurements over larger areas. Previous SERDP‐funded research resulted in new algorithms for high‐frequency acoustic data inversions and system‐independent environmental assessment in terms of measurable seabed parameters. The goal of this project is to evaluate the inversion algorithm, address its short comings for complex environments, and determine whether the data products are sufficiently accurate to warrant integration into a commercial survey tool.

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Technical Approach

To accomplish the goals of this project, researchers will collect both sonar and ground‐truth data in Sequim Bay using sonars provided by Teledyne‐RESON and the existing suite of environmental characterization tools at APL‐UW. This data will cover a wide range of environments and allow researchers to improve and test the inversion algorithm in such a way that they can clearly assess how the algorithm will perform when integrated into a commercial sonar system. While the data will be collected in a time‐consuming manner which is impractical for a wide‐area survey, the data will be used to simulate wide‐area surveys and evaluate the performance of the algorithm under different conditions and data‐acquisition choices.

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Benefits

A physics‐based, high‐frequency acoustic inversion does not require ground‐truth data, thus reducing efforts and costs for the DoD in wide‐area surveys for sediment characterization. While the inversion will be applied to multibeam echosounder data in this study, the inversion is system agnostic and can be used to supplement UXO detection sonars with sediment characterization capabilities. Ground‐truth data collected in Sequim Bay will also supplement studies of the bay for use as a UXO detection test site.

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Points of Contact

Principal Investigator

Dr. Brian Hefner

University of Washington

Phone: 206-616-7558

Program Manager

Munitions Response

SERDP and ESTCP

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