Compact Deep Vector Sensor Array
Navy SBIR 2015.1 - Topic N151-011
NAVAIR - Ms. Donna Moore -
Opens: January 15, 2015 - Closes: February 25, 2015 6:00am ET

N151-011 TITLE: Compact Deep Vector Sensor Array

TECHNOLOGY AREAS: Air Platform, Sensors, Battlespace


The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 5.4.c.(8) of the solicitation. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a deep-deployed array of vector sensors for use in an expendable sonobuoy system.

DESCRIPTION: Arrays of vector velocity sensors provide major system gains over legacy arrays of omnidirectional hydrophones in bottom moored configurations. For example, gains against ambient noise can be realized, the left-right ambiguity can be eliminated, and sensitivity nulls can be steered towards an interfering source making much quieter targets detectable. Deploying such acoustic sensing systems for use at extremely deep depths close to or on the ocean bottom (below critical depth) in convergent zone type environments has garnered recent interest in the Navy [1-3]. The advent of highly sensitive, compact directional sensors made possible by new transducer materials is a key enabler for this performance enhancement [2]. Recent investigation of the ambient noise structure in the deep ocean [3] suggests that a passive directional sonobuoy system covering the band from 5 to 500 hertz (Hz) would be of interest.

A sonobuoy array composed of a combination of omnidirectional and biaxial/triaxial sensors with an electronic noise floor of 40 decibels relative to 1 micropascal per root-hertz (dB/uPa/rtHz) is thought to be well suited for this application, taking into account possible inherent array gains against vertical anisotropic noise. The array design should be able to be deployed and operated at a depth of up to six kilometers. It should achieve nominal gains against noise of 15 dB (threshold) to 20 dB (objective) up to the 300 Hz region (can include gains associated with a combination of operational depth and array gain). The required gain against noise should be measured relative to average noise at shallow water depth, based upon the Ambient Noise Directionality System (ANDES) model [4].

The array should be capable of operating at a voltage of 5.0 volts-Direct Current (VDC) with a maximum current draw of 70 milliamps (mA). The array package must be less than 10 inches in height, no greater than 4.5 inches in diameter, and less than 15 pounds in weight (volume/weight constraint should not include power source). Because of the expendable nature of sonobuoy systems and the potential number of vector sensor elements required to realize effective gains, cost-effectiveness will also play a role in determining an acquisition choice.

PHASE I: Develop an initial conceptual design for a small inexpensive velocity sensor array, to include number and type of sensors, sensor spacing, and self-noise remediation (risks, limitations, proposed solutions). Perform modeling and simulation activities to evaluate prospective candidate arrays in realistic noise fields for various sites, sensors and depths.

PHASE II: Develop, construct, and demonstrate the operation of a prototype array through over-the-side testing utilizing electronically generated broadband and narrowband signals. Validate that the over-the-side prototype meets design goals. Provide signal processing needed to demonstrate array performance. Conduct performance predictions, design refinement, and selective hardware maturation for the high-risk components identified in Phase I.

PHASE III: Develop a production design of Phase II solution for integration into full sonobuoy system. Demonstrate full operational functionality in Navy-supported test scenarios. Transition the developed technology for fleet use and provide a detailed supportability plan.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Use of these sensors has potential applications in seismology, marine mammal detection, and terrorist security systems.

1. Urick, R. J. (1996). Deep-Sea Paths and Losses: A Summary. In D. Heiberg & J. Davis, Principles of Underwater Sound (3rd ed.) (p. 195). New York: McGraw-Hill Book Company.

2. Holler, R. A., Horbach, A. W., & McEachern, J. F. (2008). The Ears of Air ASW: A History of U.S. Navy Sonobuoys. Warminster: Navmar Applied Sciences Corporation.

3. McEachern, J. F., McConnell, J. A., Jamieson, J., and Trivett, D. (2006). ARAP Deep Ocean Vector Sensor Research Array. MTS/IEEE OCEANS 2006, 1-5. doi:101.1109/OCEANS.2006.307082

4. Leigh, C. V., & Eller, A. I. (2006). Dynamic Ambient Noise Model Comparison with Point Sur, California, In Situ Data. Seatle, WA: University of Washington Applied Physics Laboratory. Retrieved from:

5. Shipps, J. C., & Deng, K. (2003). A Miniature Vector Sensor for Line Array Applications. Oceans 2003 Marine Technology and Ocean Science Conference Proceedings, 5, 2367-2370. doi:10.1109/OCEANS.2003.4178284

6. Gaul, R. D.,Knobles, D. P.,Shooter, J. A., &&Wittenborn, A. F. (2007). Ambient Noise Analysis of Deep-Ocean Measurements in the Northeast Pacific. IEEE Journal of Oceanic Engineering, 32(2), 497 512. doi:10.1109/JOE.2007.891885

KEYWORDS: Passive; Asw; Sonobuoy; Vector Sensor; Reliable Acoustic Path; Deep Ocean

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