N151-013 TITLE: Deep Long Life Passive Sonobuoy Sensor System

TECHNOLOGY AREAS: Air Platform, Sensors, Battlespace

ACQUISITION PROGRAM: PMA 264

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, long life, passive sonobuoy sensor system that can be deployed by aircraft and used for undersea surveillance.

DESCRIPTION: The Navy is becoming increasingly interested in deploying acoustic sensing systems below critical depth in the ocean close to or on the ocean bottom in convergent zone type environments [1]. At these depths the ambient noise structure and sound propagation physics are unique [2] and have the potential to be exploited by future undersea surveillance systems. The concept of utilizing deep sonobuoy systems is not new; in the 1970�s there were efforts to place sensors deep in the ocean. Two sonobuoy concepts were considered: an On-the-Bottom (OTB) Directional Frequency Analysis and Recording (DIFAR) and a 14,000 feet Deep Suspended DIFAR (DSD) [3]. Recent investigation of the ambient noise structure in the deep ocean [2] suggests that a passive directional sonobuoy system covering the band from 5 to 500 hertz (Hz) would be of interest. When the sea state is calm and there is little distant shipping, the ambient levels are nominally 40 to 50 decibel (dB) are 1 microPascal^2/Hz [2]. A sonobuoy array composed of a combination of omnidirectional and biaxial sensors with an electronic noise floor of 40 dB/microPascal^2/Hz is thought to be well suited for this application particularly in view of array gains that are possible as a result of the vertical anisotropic noise field. What is desired is an A-size sonobuoy which can be deployed from an aircraft and operate at or close to the ocean bottom (up to 6 km). The sonobuoy will have a minimal operational life of 3 to 14 days and be capable of storing data until commanded to exfiltrate the data to an aircraft or periodically to an over the horizon location. It is expected that In-Buoy Signal Processing (IBSP) will be needed to reduce the data transfer rate and in-buoy data storage. IBSP will, as a minimum, consist of acoustic beamforming (possibly adaptive) and both narrowband and broadband processing. For data exfiltration from the array up to the radio frequency (RF) communication link, consideration should be given to data rates from the array, pressure and temperature variations across depths as well as survivability. It is expected that array design, long life, deep depth survival and data exfiltration will require innovative solutions because of the A-size packaging constraints [4].

The RF communication link should conform to the receive capability of the air platform which is composed of Continuous Phase Gaussian Frequency Shift Keying (CPGFSK) waveform of 320 kilobits per second (kbps) for which 288 kbps can be acoustic data.

Note that A-size refers to the standard U.S. Navy Sonobuoy form factor or a right-circular cylinder having a diameter (D), length (L), and maximum weight (W) of D=4.875 inches, L=36 inches, and W=39 pounds.

PHASE I: Develop approaches, and perform modeling and simulation activities to evaluate prospective designs associated with the sensor type(s), array, telemetry, packaging, deployment, and self-noise remediation within the overall architecture of an A-size sonobuoy.

PHASE II: Conduct performance predictions, design refinement, and selective hardware maturation for the high-risk components identified in Phase I, and develop a prototype sonobuoy.

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

REFERENCES:
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. 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

3. 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.

4. 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

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

** TOPIC AUTHOR (TPOC) **

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