TECHNOLOGY AREAS: Sensors, Electronics

ACQUISITION PROGRAM: PMS 415 –Acoustic Augmentation Support Project, not a "ACAT level" program.

OBJECTIVE: Conduct a research and development effort to develop a transducer capable of providing continuous wave (CW) output of simultaneous narrowband tones and broadband noise in a frequency band from 1kHz down to 10Hz at output levels not less than 150 dB (referenced to 1 micro-pascal at 1 meter) over the entire operating spectrum of the transducer. While in a standby condition the transducer should not produce any appreciable acoustic signal. In depth knowledge of the Navy, submarines, and ASW techniques is not required for the first or second phases of this SBIR. The work being done under this SBIR will be unclassified.

DESCRIPTION: The Acoustic augmentation Support Project (AASP) provides a temporary system that is used to produce acoustic signals across an operating band of 10Hz to 44kHz. These signals are used by the Navy for team training exercises in anti-submarine warfare (ASW). The AASP system, as it is currently configured, consists of a drive computer, 2 power amplifiers, and 3 transducers. One of the transducers supports the VLF frequency spectrum, one supports the LF to MF frequency spectrum, and the last supports the HF frequency spectrum. The problem with the AASP system lies primarily with the HLF-1 transducer that supports the system’s VLF frequency band. The transducer options currently available to the Navy to support the VLF spectrum of AASP all have limitations such as external compensation, excessively large size, high power draw, etc. The transducer currently used by the Navy to fill this role is a hydro-acoustic design (HLF-1) which does not meet the source level requirements that would satisfy the Navy’s current interest in high source level/VLF signals, and, when in a standby mode, this transducer contributes unwanted signals that are natural artifacts of the rotating machinery inside the transducer.

Because of the problems stated above the AASP system cannot completely satisfy the requirements of the Navy at frequencies below 60 Hz. When the system attempts to produce a complex signal with a high level VLF component, the HLF-1 will overdrive and go into oscillation resulting in an unnatural signal with a high source level. The R&D effort generated as a result of this SBIR should design a new transducer that is capable of generating simultaneous broadband and narrowband acoustic signals at frequencies down to 10 Hz and at source levels of not less than 150dB (referenced to 1 micro-pascal at 1 meter) over the entire operating spectrum of the transducer. While in a standby condition the transducer should not produce any appreciable acoustic signal.

PHASE I: Conduct a research and development (R&D) effort to design a VLF transducer to meet the goals stated in the objectives section of this paper. Develop details for the design and provide theoretical reasons for expected acoustic performance. Develop conceptual drawings of the transducer including physical size, means of compensation, and means of transduction. Estimate the time to manufacture, cost to manufacture, and the transducer’s expected VLF performance. The transducer‘s design should be capable of fitting within existing spaces on all U.S. submarines. The dimensions of the mounting spaces for the current transducer are listed in the reference documentation. If available, modeling of the transducer’s physical size, and theoretical operating characteristics should accompany the candidate transducer.

PHASE II: Develop and assemble an Engineering Development Model (EDM) of the VLF transducer. Conduct tests of the EDM prototype VLF transducer in acoustic free-field conditions at depths varying from 50 to 1000 ft. to determine the ability of the prototype VLF transducer to produce an omni-directional noise field in both the vertical and the horizontal axes. Determine the ability of the prototype VLF transducer to simultaneous produce complex narrow band and broadband signals. Determine the ability of the prototype VLF transducer to remain in an energized "standby" condition and not produce any unwanted acoustic artifacts.

PHASE III: Take the information gathered from the EDM transducer tests and develop a production model transducer. Conduct tests of the production model transducer to verify it’s ability to meet the Navy’s needs. Support integration of the production VLF transducer into the AASP system (mechanical, electrical and control system design). Lab based integration tests should be performed at the system level to validate system compatibility and transducer performance. These laboratory tests should be followed by system level testing in a relevant environment at full scale. All testing should be coupled with continued design modification to reduce the incidence of future developmental efforts.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The resulting VLF transducer would greatly aid in the areas of underwater tomography, oil exploration, and fisheries biology.

REFERENCES:
1. Acoustic Augmentation Temporary Alteration for SSN-774 Class Submarines (TempAlt 06-0007 Rev B).

2. Acoustic augmentation Temporary alteration for SSBN/SSGN 726 Class Submarines (TempAlt 183.02R4).

3. NUWC-NPT Technical Memo 05-047A HLF-1 Government Acceptance Specification

4. NUWCDIVNPT Code 1511 Technical Memo 92162/001A Acoustic Augmentation suppport Program (AASP) System Operation and Troubleshooting Manual for SSN-688, SSBN/SSGN-726, and SSN-774 Class Submarines 20 April 2009.

5. NUWC-NPT Technical Document 11,854 dated 1 Sept 2009 Acoustic Augmentation support Program Equipment Installation and Removal Procedures for Virginia-Class Submarines.

KEYWORDS: VLF transducer; VLF acoustic augmentation; noise augmentation unit; AASP; NAU; underwater transducer

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between July 20 and August 16, 2010, you may talk directly with the Topic Authors to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting August 17, when DoD begins accepting proposals for this solicitation.

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