N101-062 TITLE: Improved Torpedo Defense

TECHNOLOGY AREAS: Sensors

ACQUISITION PROGRAM: PMS-415: Anti-Torpedo Torpedo Defense System: ACAT II

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: Develop innovative technology to resolve closely spaced approaching torpedo salvos near end-fire of towed sensors.

DESCRIPTION: A difficult technical challenge for surface ship torpedo defense is the spatial resolution of closely spaced multi-torpedo salvos. Passive detection and localization are typically done with towed line arrays, which have been shown to localize well and resolve multiple targets near broadside with state-of-the-art processing (see reference 1, chapter 9). Target resolution near end-fire is much more difficult because of the broader line array beamwidths, and the inability to use wavefront curvature or triangulation with hull-mounted sensors. Innovative approaches are solicited.

The objective of this topic is to perform R&D that will clearly establish the technical feasibility of end-fire salvo resolution. Torpedoes are typically loud passive acoustic emitters with significant broadband energy from 0- 30 kHz. (Reference 3 describes typical broadband signatures of ocean vehicles.) Satisfactory performance would provide resolution of targets separated by 50-100 yards at ranges of 1000-5000 yards.

Proposed techniques may include innovative passive signal processing techniques, model-based approaches, matched field processing (reference 2), exploitation of acoustic propagation effects, Doppler, etc. The Navy�s primary interest is in towed array solutions but multi-sensor (tow ship sonar and towed array) solutions are also of interest. Significant flexibility in proposed approaches will be accommodated.

Spectral identification or other exploitation of classified torpedo signature information is not required to address this topic.

PHASE I: Describe the proposed approach for end-fire salvo resolution and conduct analysis to show feasibility of the approach.

PHASE II: Design and build a prototype of the proposed salvo resolution technique for evaluation. Evaluate performance on the prototype using synthetic or recorded data.

PHASE III: Conduct full scale testing of the technique in an operational environment such as a sea test. Integrate successful improvements into Navy torpedo defense systems (e.g., ATTDS, AN/SQQ-89).

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATION: This technology can be applied to commercial applications in which detection and resolution (separation) of multiple objects is required using sensor arrays. Commercial applications would include array-based cell phone signaling, seismology, medical imaging and law enforcement (gunshot detection/localization).

REFERENCES:
1. H.L. Van Trees, Optimum Array Processing. Wiley, New York, 2002.

2. A.B. Baggeroer, W.A. Kuperman, P.N. Mikhalevsky, "An Overview of Matched Field Methods in Ocean Acoustics," IEEE J. Oceanic Eng, vol.18, No. 4, October 1993.

3. R.J. Urick, Principles of Underwater Sound, McGraw Hill, New York, 1983.

4. A.B. Baggeroer and H. Cox, Passive Sonar Limits upon Nulling Multiple Moving Ships with Large Aperture Arrays, 33rd ASILOMAR Conference on Signals Systems and Computers, Vol. 1, pp. 103-108, 1999.

KEYWORDS: Keywords: torpedo defense; detection; multiple targets; localization; acoustic sensors; sonar

** TOPIC AUTHOR (TPOC) **

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