N092-108 TITLE: Single Crystal Transducer Technology for Undersea Tracking Ranges

TECHNOLOGY AREAS: Ground/Sea Vehicles, Sensors

ACQUISITION PROGRAM: PMA-264, Air Anti Submarine Warfare Systems

OBJECTIVE: This project will provide the research and design for application of single crystal lead magnesium niobate-lead titanate (PMN-PT) to undersea tracking ranges.

DESCRIPTION: Undersea tracking is used to monitor and assess the performance of submarines, torpedoes, ships and targets conducting tests and exercises on weapon system performance. They are also used to evaluate crew efficiency during training exercises. The ability to track these platforms is based on the transmission of coded signals to and from instrumentation installed on the ocean bottom. The quantity of instrumentation is dependent largely on the sensitivity of the sensors, the power level transmitted and the signal degradation caused as sound travels through the water. Current state-of-the-art piezo-electric ceramic transducers are limited by depth, bandwidth, and life cycle.

Innovative solutions are sought that would increase the sensor performance through the use of a newly developed transducer material. This material (lead magnesium niobate-lead titanate (PMN-PT), commonly known as single crystal), demonstrates the potential to provide greater sensitivity, power and bandwidth versus traditional materials. If these characteristics can be harnessed, it would enable the design of tracking systems requiring a smaller quantity of sensors reducing the system's acquisition cost. The challenge of this topic comes from the application of PMN-PT to meet the unique transducer performance requirements for undersea tracking ranges. Viable designs should exhibit the following characteristics: acoustic receiver sensitivity of -195 dB re uPa or better; acoustic receiver bandwidths from 8 KHz - 45 KHz (minimum) and 100 Hz to 75 KHz (goal); acoustic source levels of 195 dB re 1 uPa or greater; source bandwidths from 8 KHz - 14 KHz (minimum) and 2 KHz - 20 KHz (goal); operating depth to 6000 feet (minimum) and 20,000 feet (goal); transmission duty cycles capable of continuous transmissions for 30 seconds at a 50% duty cycle indefinitely (30 seconds on, 30 seconds off) indefinitely; nominal operating life of 20 years.

PHASE I: Demonstrate proof-of-concept of proposed design. Analyze performance predictions of beampatterns, sensitivity, power efficiency, bandwidth, operating depth, operating duty cycle and output power level.

PHASE II: Develop a prototype tranducer and test the design. The prototype should be tested to characterize all aspects of its performance. System interfaces should be defined for integration in range designs including electrical parameters for both transmission and reception and mechanical mounting and protection for deep ocean environments.

PHASE III: Transition the use of the single crystal technology from Phase II as the basis for Undersea Warfare Training Range system design. This will include direct reflection and use of the capabilities to implement the transmit and receive functionality required to monitor and track vehicles operating on the range.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Acoustic sub-bottom profiling is performed by energy companies and researchers to characterize sedimentation, silt depositions and ocean bottom structure. These devices use sonar sources operating from a few Hz to 10s of KHz (10 - 40 KHz in one example). This frequency range substantially overlaps the Navy's frequency band of interest since most tracking range designs cover a 50 Hz - 40 KHz band.

REFERENCES:
1. Harold C. Robinson, James M. Powers, and Mark B. Moffett, "Development of broadband, high power single crystal transducers," Proceedings of the 2006 SPIE International Symposium on Smart Structures and Materials, in press (2006).

2. Advanced Piezoelectric Single Crystal Based Transducers for Naval Sonar Applications. Snook, K.A.; Rehrig, P.W.; Xiaoning Jiang; Hackenberger, W.S.; Meyer, R.J.; Markley, D., Ultrasonics Symposium, 2005 IEEE. Volume 2, Issue , 18-21 Sept. 2005 Page(s): 1065 - 1068

3. Single Crystal Cylinder Transducers for Sonar Applications. Robinson, Harold; Stevens, Gerald; Buffman, Martin; Powers, James. Acoustical Society of America Journal, Volume 117, Issue 4, pp. 2447-2447 (2005).

4. Single Crystal Naval Transducer Development. Powers, J.M.; Moffett, M.B.; Nussbaum, F. Applications of Ferroelectrics, 2000. ISAF 2000. Proceedings of the 2000 12th IEEE International Symposium on Volume 1, Issue , 2000 Page(s):351 - 354 vol. 1.

KEYWORDS: Transducers; Sensor; Acoustic; Single Crystal; Tracking; Undersea

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