Towed Array Position Estimation System
Navy SBIR 2020.1 - Topic N201-049
NAVSEA - Mr. Dean Putnam -
Opens: January 14, 2020 - Closes: February 26, 2020 (8:00 PM ET)


TITLE: Towed Array Position Estimation System


TECHNOLOGY AREA(S): Battlespace, Electronics, Sensors

ACQUISITION PROGRAM: PEO IWS 5, PMS 401: Submarine Acoustic Systems Program Office.

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 3.5 of the Announcement. 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 system for determining the position of the headline of the towed array relative to some fixed point on the towing platform for incorporation into future towed arrays.

DESCRIPTION: The Navy uses towed acoustic sensor arrays and hull-mounted acoustic sensors to detect submerged and surface vessels. Each type of sensor provides unique capabilities [Ref. 1]. In order to take advantage of capability overlap, it is critical to know key parameters about both systems, including physical location of towed acoustic sensors relative to each other. However, the ability to combine these capabilities is limited because state-of-the-art technology cannot accurately locate the towed array relative to the hull array.

Co-processing sensors provides two main benefits: increasing gain by increasing the number of channels and aperture at the design frequency; and allowing for target ranging and localization (triangulating). The required accuracy is a function of the design frequency of the array. Two (2) wavelengths are sufficient accuracy for position measurement for co-processing purposes [Ref. 2].

The Navy seeks an innovative solution to determine the relative positions of the towed and hull arrays to support coherent processing of the combined arrays. This capability will assist the Navy in maintaining or increasing its tactical advantage in the undersea warfare (USW) domain. While the Navy currently has many capable hull-mounted and towed sensors, there is currently no means to process the towed and hull sensors coherently with each other in order to provide increased awareness of the battlespace and overall performance improvement. The solution sought will provide, in three dimensions, accurate (relative to the wavelength correlating to the design frequency of the array in question), near real-time (less than one sample delay relative to the array sample rate) position data of the towed array headline relative to some fixed point on the towing platform. The array headline position is the most important position, but fully locating the entire array would be of additional interest to the Navy. The desired capability must also permit the desirable capabilities in currently fielded technologies (such as the capability some multi-line towed array systems use to report relative positions of each of several towed lines to each other) [Ref. 3].

The proposed solution must be suitable for packaging within towed arrays (no more than 5.1” long, 0.75” in diameter) and must not cause elevated signatures (e.g., acoustic or electro-magnetic) in a manner that makes the towing platform more detectable. Specifically, the system shall not generate any detectable signals above ambient conditions at a range of 100 yards. While modeling solutions may be part of the solution, it is anticipated that sensor-based elements will be required to achieve sufficient accuracy to attain the desired coherent processing.

Sensor elements associated with the proposed solution must survive extreme environments (as described below) during deployment and must maintain their accuracy within 10% of nominal (inclusive of drift) over the requirements described below. The sensor element(s) must suffer no degradation over a fifteen-year span from time of first use while operating at pressures up to 1200 psi, temperatures over a range of -28°C to 50°C, and accelerations up to 100 Hz over a range of 0.0 g to 25.0 g. The reliability of the sensor element(s) will need to support a Mean Time between Failure (MTBF) of at least 7,000 hours. Testing to validate the technology meets these requirements will be performed at the Naval Undersea Warfare Center in Newport, RI, or at the contractor’s facility if deemed sufficient by the Government.

Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. Owned and Operated with no Foreign Influence as defined by DOD 5220.22-M, National Industrial Security Program Operating Manual, unless acceptable mitigating procedures can and have been be implemented and approved by the Defense Security Service (DSS). The selected contractor and/or subcontractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances, in order to perform on advanced phases of this contract as set forth by DSS and NAVSEA in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material IAW DoD 5220.22-M during the advance phases of this contract.

PHASE I: Develop a concept for determining the position of the headline of the towed array relative to a fixed point on the towing platform. Demonstrate that the concept can feasibly meet all requirements in the Description. Establish feasibility through modeling and analysis. The Phase I Option, if exercised, will include the initial system specifications and capabilities description to build a prototype solution in Phase II.

PHASE II: Develop and deliver a prototype system for testing. (Note: The Government will provide support for packaging the system within the towed array.) Validate the prototype through testing. Demonstrate that the position of the headline of the towed array does not negatively affect the detectability of the towing platform. Perform testing and validation at a Government-provided facility.

It is probable that the work under this effort will be classified under Phase II (see Description section for details).

PHASE III DUAL USE APPLICATIONS: Assist the Government in transitioning the technology for Navy use. Conduct experimentation and refinement to qualify the technology for use on towed arrays within the Advanced Processing Build process. (Note: The Government will provide the performer access to a Navy ship where the final system validation and performance verification will be conducted.) Support installation and removal from an at-sea test platform and assist in data recovery and processing. Use the resulting data to verify the measurements and accuracy of the system.

This technology would prove useful for oceanographic research, oil and gas exploration, congested area traffic monitoring, and other applications where data from multiple disparate sensors are fused to provide a more holistic awareness of the volume being monitored by sensors, especially where sensors are not in fixed locations.


1. Lemon, S. G. "Towed-Array History, 1917-2003." IEEE Journal of Oceanic Engineering, Vol. 29, No. 2, April 2004, pp. 365- 373.

2. Burdic, William S. “Underwater Acoustic System Analysis.” Prentice-Hall, Inc.: New Jersey, 1991.

3. Chandrasekhar, Vijay et al. “Localization in Underwater Sensor Networks — Survey and Challenges.” 2006 Proceedings of the 1st ACM International Workshop on Underwater Networks (WUWNet), pp.33-40.

KEYWORDS: Towed Array; Sensor Fusion; Position Measurement; Acoustic Detectability; Measurement Certainty