TECHNOLOGY AREAS: Sensors

ACQUISITION PROGRAM: PMS 397 OHIO Replacement Program, ACAT I

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: The Navy has a need for specialized acoustic sensors to provide high array gain and high resolution for source localization. An underwater volumetric array is needed to achieve high array gain (> 28 dB) in the frequency range of 10-80 kHz in order to acquire special acoustic measurements for full and model scale submarines.

DESCRIPTION: The Navy has a need for specialized acoustic sensors to provide high array gain and high resolution source localization. Current technology to support this need has numerous shortcomings in areas that effect sensitivity, directivity and noise floor. Achieving accurate measurements in the upper frequency ranges will be particularly challenging. To achieve beamformed outputs with high array gain, a large quantity of low noise sensors will be required. To achieve the high frequency performance, the individual sensors will need to be small and packed close together. Isolating these sensors from non-direct acoustic paths, structural vibrations, and electrically coupling from adjacent sensors will require innovation in design of both the sensor and mounting configuration. Key components to this research include developing a low noise, high sensitivity acoustic sensor that can be continuously deployed in the ocean for a 10-15 year operational life. The sensor and beamformed array outputs must be capable of being calibrated both electrically and acoustically to provide sound pressure levels that can be certified to a NIST reference standard. Additionally, the array shall be capable, with the aid of advanced beamforming techniques, of resolving broadband and narrowband sources with low SNR with a precision of two feet or less.

PHASE I: Develop a conceptual design for a high gain (>28db), very high frequency (10 kHz to 80 kHz) underwater acoustic volumetric array. Perform modeling and simulate candidate array designs in realistic noise fields at various sites, sensors and depths. Develop and/or utilize innovative sensor materials that incorporate compact, low power electronics into a packaging concept that is easily deployed for a 10-15 year operational life.

PHASE II: Develop, construct, and demonstrate the operation of a prototype high frequency volumetric array through laboratory and over-the-side testing utilizing electronically generated broadband and narrowband signals. Validate that the prototype meets the design goal for array gain and source localization. Provide signal processing needed to demonstrate array performance. Complete component design, expected sensor life analysis, and a deployable packaging concept.

PHASE III: Develop a production design of the Phase II solution. Demonstrate full operational functionality in full and model scale Navy supported test scenarios. Transition the developed technology for Navy acoustic facility use and provide a detailed supportability plan.

PRIVATE SECTOR COMMERCIAL POTENTIAL: High array gain and associated beamforming technologies have potential application in the medical industry.

REFERENCES:
1. D. C. Bertilone, D. S. Killeen, and C. Bao, "Array Gain for a Cylindrical Array with Baffle Scatter Effects", J. Acoustic Soc. Am, Vol 122, Issue 5, Nov 2007, pp. 2679-2685.

2. H. L. Van Trees, "Optimum Array Processing", Part IV of Detection, Estimation and Modulation Theory, Wiley-Interscience, New York, 2002

3. E. A. Skelton and J. H. James, "Theoretical Acoustics of Underwater Structures", Imperial College Press, London, 1997.

4. J. L. Butler and A. L. Butler, " A Tri-modal Directional Transducer", J. Acoustic Soc. Am, Vol 115, Issue 2, Feb 2004, pp. 658-665.

5. C. LeBlanc, "Handbook of Hydrophone Element Design Technology", NUSC, Oct 1978, pp. 4-27.

6. Sullivan and Powers, "Piezoelectric Polymer Flexural Disk Hydrophone", J. Acoustic Soc. Am., 63(5), May 1978, pp. 1396-1401.

7. Holden, Parsons, and Wilson, "Flexural Disk Hydrophones Using Polyvinylidene Flouride (PVDF) Piezoelectric Film: Desensitization with Increasing Hydrostatic Pressure:, J. Acoustic Soc. Am., 73(5), May 1983, pp. 1852-1862.

KEYWORDS: Volumetric array; array gain; high frequency; underwater sensor; source localization;

** TOPIC AUTHOR (TPOC) **

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