Multi-Static Processing Using Sonobuoys as Opportunistic Receivers
Navy SBIR 2013.1 - Topic N131-030
NAVSEA - Mr. Dean Putnam - dean.r.putnam@navy.mil
Opens: December 17, 2012 - Closes: January 16, 2013

N131-030 TITLE: Multi-Static Processing Using Sonobuoys as Opportunistic Receivers

TECHNOLOGY AREAS: Sensors

ACQUISITION PROGRAM: PEOIWS 5E, Anti-Submarine Warfare Command and Control Systems

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 object is to develop new processing algorithms to use sonobuoys as opportunistic multi-static receivers with other deployed active processing systems.

DESCRIPTION: The Navy has a need to extend the range and accuracy of existing sonar sensors; to increase warfighter capabilities by providing on-scene operators with more sonar options and courses of actions for Anti-Submarine Warfare (ASW) tactics; and to enhance platform inter-operability and coordinated ASW operations while ensuring that operators on the carrier and escort ships can view detection and tracking results on a common tactical picture. Successful development and fleet deployment of sonobuoy multi-static algorithms will improve ASW’s strike-group mission to better protect the carrier and escort ships from ASW threats. Sonar performance will achieve increased detection probability, increased detection range, increased submarine holding time, and increased success of submarine prosecution. Mission capability will be improved relative to the current system in which operators only have a mono-static option. A new technology will meet the need to improve performance and capability.

Sonobuoys provide the Navy with a unique capability as a remote sensor for ASW search and prosecution. There are two types of sonobuoys, passive and active. Passive sonobuoys, such as Frequency Analysis and Recording (DIFAR) Sonobuoys, are covert omni or directional receivers. They are used to Detect, Classify and Localize (DCL) threats. Active sonobuoys, such as the Directional Command Active Sonobuoy System (DICASS), are low power mono-static active sensors used for localization, tracking, and prosecution. Ref (1) describes current sonobuoy signal processing algorithms to improve detection, and resolve the bearing estimation ambiguity when processing widely spaced omni-directional sonobuoys arrays. Increasingly, coordination is required to manage the acoustic interference between Navy platforms to avoid false alarms in sonobuoy processing. This interference is caused by mutual acoustic interference from other active sensors (i.e. Surface combatant hull-mounted sonars, surface ship variable-depth active sonars, and helicopter-deployed Dipping sonars, such as the Airborne Low-Frequency Sonar (ALFS)).

The mutual acoustic interference described above can be used as a capability multiplier to perform opportunistic bi-static processing using a passive sonobuoy as the receiver and one or more cooperative active sources. Ref (2) highlights the performance potential of sonobuoys operating in a chokepoint in conjunction with a standoff sound source to create a barrier to submarine transit.

The Navy seeks acoustic processing algorithms that exploit multi-static active processing from sonobuoy receivers in conjunction with the cooperative active sources. The technology gap to be filled includes signal processing that uses the direct path pulse replica for both the matched filter processing and the timing basis to synchronize bi-static active source transmission with receiver processing as well as algorithms to exploit multi-static active processing with multiple sonobuoy receivers. The signal processing algorithms will be applied to systems with active or passive sonar systems (I.E. AN/SQQ-89, AN/SQQ-34, MH-60R, P-3).

The Phase I effort will not require access to classified information. If need be, data of the same level of complexity as secured data will be provided to support Phase I work. The Phase II effort will likely require secure access, and the contractor will need to be prepared for personnel and facility certification for secure access.

PHASE I: Based on analysis of currently fielded active sonar systems and various passive and active sonobuoy receive bands, and candidate pairings of platform mounted active sonar and sonobuoy receivers, the company will develop a concept and conduct a feasibility analysis for bi-static processing, assuming the known locations of the transmitter and sonobuoy receivers and the time of pulse transmission. The company will generate an acoustic simulation of a source/receiver pairing and candidate processing algorithms as a proof of concept. The company will provide a Phase II development plan with performance goals, technical metrics, and key technical milestones. The development plan will address technical risk reduction for bi-static sonobuoy operations. The company will show feasibility of the technology development efforts and suitability of the technology for meeting Navy requirements.

PHASE II: Based on the results of Phase I algorithm assessments and the Phase II development plan, the company will develop a prototype system hosting the bi-static algorithms suitable for evaluation using calibrated simulator data and at-sea data recordings of sonobuoys and active sources. The company will measure prototype detection, localization, and tracking improvements relative to baseline monostatic sonobuoy performance. The results of this prototype assessment will be used to refine the processing algorithms, in order to support an evaluation of the capability using a government provided closed data set. The company will prepare a Phase III development plan to transition the technology to Navy use.

PHASE III: If Phase II is successful, the company will be expected to support the Navy in transitioning the technology into one or more ASW programs employing sonobuoys. Candidate transition programs include the aircraft carrier ASW combat system (CV-TSC), the MH-60R helicopter ASW system, and the AN/SQQ-89 surface ship ASW combat system. Specifically, the company will develop formal specifications, software, test documentation, and training support material necessary to complete the transition. Software for new algorithms and system interfaces will be developed in a distributed object processing framework implemented in the Java programming language. The company will tailor algorithms and system interfaces to be compatible with ASW systems on different platforms. The company will support the Navy and prime contractors for test and validation to certify and qualify the system for Navy use.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: A bi-static configuration of ultra-sonic sensors could be used for non-intrusive medical analysis where high-resolution object location and temporal analysis is needed. Also, acoustic security systems using low-power sources and fixed receivers with bi-static detection algorithms improve detection and localization accuracy against surface and subsurface objects

REFERENCES:
1. Osman, Abdalla; Noureldin, Aboelmagd. "Array Processing of Passive Sonobuoys for Underwater Target Tracking: Advanced Signal Processing Techniques." LAP LAMBERT Academic Publishing, August 8, 2010.

2. Been, R., Jespers S.; Coraluppi, S.; Carthel, C.; Wathelet, A.; Strode, C., Vermeij, A. "Multistatic Sonar: A Road to a Maritime Network Enabled Capability." NATO Undersea Research Centre, Viale San Bartolomeo 400, 19126 La Spezia, Italy, October 2007.

KEYWORDS: Monostatic acoustic receiver; active sonar; passive sonar; bi-static sonobuoy, multi-static sonobuoy, detection, localization, and tracking

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