N112-150 TITLE: Through the Sensor Active Sonar Enhancement

TECHNOLOGY AREAS: Sensors, Battlespace

ACQUISITION PROGRAM: PEO IWS Surface Advanced Capability Build (ACB)

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports):  This topic is "ITAR Restricted."  The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data.  Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: To develop robust and efficient techniques which utilize in situ sonar data to estimate parameters that effect temporal changes in the local range- and depth-dependent probability of detection versus probability of false alarm (PD/PFA) for improved performance prediction and potentially target recognition in active sonar systems.

DESCRIPTION: Mid-frequency (MF) active sonar performance prediction accuracy depends critically on the estimate of the range-dependent sound speed profile (SSP) and a variety of often unpredictable sources of reverberation and clutter. Through visual analysis and integration of sonar returns, trained operators and analysts are able to infer qualitative changes in reverberation, clutter, and the SSP and estimate the impacts on PD/PFA. Rapid automated quantification of these changes that could be folded back into sonar performance predications would support enhanced tactical decisions and could also support estimates of the temporal coherence and uncertainty associated with the predictions. Ideally, the automated analysis products would also serve to improve the recognition differential of the operators.

PHASE I: Utilizing unclassified mono-static and bi-static sonar data provided under the PH I contract, analyze and develop techniques to be used to estimate key parameters in sonar performance prediction for the given data and propose concepts for extending the methods to a wider variety of systems and scenarios. The effort may include model-based trials and development in addition to the data analysis.

PHASE II: Expand testing to include operational sonar data and conduct proof-of-concept demonstrations and tests of methods developed under the PH I program. Refine the methodology, develop metrics, and complete system verification and validation demonstration and testing. Develop a system employment concept of operations. SECRET clearance will be required for Phase II.

PHASE III: Deploy the prototype parameter estimation system on a Navy operational platform, support the at-sea testing, identify operational constraints and obtain end user feedback which can be used to improve the overall tool prior to transition under the ACB process. SECRET clearance will be required for Phase III.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Direct system application is limited, but the concepts may be leveraged to enhance other efforts that rely on sound propagation in the ocean: the commercial fishery, oil and gas exploration (seismic), and marine construction industries. In many cases environmental compliance and determination of risk to protected marine mammals from their activities is necessary, and ncreasingly these endeavors will have to rely on active sonar systems to monitor the area for marine mamnals in order to effectively employ mitigation measures (e.g. cease operations when marine mammals enter an exlcusion zone).

REFERENCES:
[1] Urick, R.J., Principles of Underwater Sound, Third Edition, McGraw-Hill Book Company, 1983.

[2] Medwin, H. and Clay, C.S., Fundamentals of Acoustical Oceanography, Wiley, New York, 1977.

[3] Backus, G. E., and J. F. Gilbert, Numerical Applications of a Formalism for Geophysical Inverse Problems, Geophys. J. R. Astron. Soc., 13, 247�276, 1967.

[4] Candy, J.V., Bayesian Signal Processing, John Wiley and Sons, 2009.

[5] Taroudakis, M.I. and Makrakis, G.N. Editors, Inverse Problems in Underwater Acoustics, Springer-Verlag, 2001

[6] Sambridge, M. and Mosegaard, K., Monte Carlo Methods in Geophysical Inverse Problems, Reviews of Geophysics, 40, 3, September 2002.

KEYWORDS: Sonar, Acoustic Performance Prediction, Estimation, Inversion, Simulation, Acoustical Oceanography

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