It is the U.S. Navy's policy to maintain acoustic standards of measurement to certify performance of test and measuring equipment. The impetus for this effort is to ensure consistent and accurate measurements for research, development, inspection, acceptance and maintenance of ships, aircraft, and weapon systems. The National Institute of Standards and Technology (NIST) performs the governmental function of providing standards in areas except underwater sound.
The Underwater Sound Reference Division (USRD) at the Naval Undersea Warfare Center (NUWC) in Newport, Rhode Island performs as the equivalent to NIST in underwater acoustics with traceability to NIST electrical voltage and current standards. Consistent with this role, USRD provides the U.S. with a wide variety of underwater transducer standards.
USRD transducer standards are used to verify specifications, to show conformance with contractual obligations, to show conformance with environmental laws, and to provide a reference base for advancing science and technology within the underwater acoustics community. Approximately 45% of the customers for these transducers are from various parts of the U.S. government and 55% of these customers are from commercial industry, universities, and state governments. Once authorized, loans to foreign governments are treated the same as loans to U.S. governmental agencies.
The intended use, the measurement environment, and the frequency range of interest determine the type of transducer that is best suited to the application. Based on this information, the USRD staff can help select an appropriate transducer. For general guidance, refer to the chart of transducer specifications below.
USRD charges a loan fee for use of transducers in order to recover incurred costs. The full amount of the loan fee must be received prior to shipment of a transducer. Normally, the loan fee provides for shipping costs, 30 meters of underwater electrical cable, a standard calibration (free-field voltage sensitivity and/or typical transmitting response), and minor repair or maintenance of a transducer. If a transducer is lost or severely damaged, a replacement or repair fee is charged.
Products and services include:
- Defense, commercial and university acoustic transducer and transducer array engineering
- Underwater acoustic transducer narrow and wide band frequency applications
- Shallow and deep water transducers and arrays
- Active and/or passive transducers and arrays
- Transducer materials of choice: ceramic, composite, PVDF or single crystal, etc.
- Research and Development
- Design and prototyping
- Fabrication and qualification testing