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Intercomparison to validate calibration methods for hydrophones in the frequency range 10-315 kHz.

Robinson, S P; Green, G J (1997) Intercomparison to validate calibration methods for hydrophones in the frequency range 10-315 kHz. NPL Report. CIRA(EXT)020

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Abstract

This document is the Final Report for EC contract number MAS2-CT94-0095 entitled Intercomparison to validate calibration methods for hydrophones in the frequency range 10-15 kHz. This two-year project was funded partly by the Directorate-General for Science, Research and Development of the Commission of the European Communities, and partly by the UK DTI. Although the contract has been funded by the EC under the Marine Science and Technology Programme, it was administered through the Standards, Measurement and Testing Programme.
The aim of the project was to carry out a European intercomparison of hydrophone calibrations in the frequency range 10-315 kHz in order to validate existing standards and methods and to identify areas where improvements are required. The intercomparison has been organised radially with the coordinator, NPL, taking a central role. A total of 12 participants from 7 European countries have calibrated three reference hydrophones, with NPL performing the coordination, inter-participant checks on the hydrophones, fmal analysis and reporting of results.
The agreement between the results of participants was such that a majority of the results were within ±1 dB of the Grand Mean. In general, this is encouraging and reflects well upon the expertise of the participants. Nevertheless, it still means that calibrations originating from two different countries could easily disagree by 2 dB, which could lead to serious and potentially expensive disagreements in measured values when the hydrophones are used in the field. In addition, some large variations were observed which give cause for concern. The uncertainties in the calibrations were typically under-estimated by the participants, with the maximum differences from the Grand Means almost invariably exceeding the quoted overall uncertainties. The report concludes with a discussion of possible further work identified as a result of undertaking the intercomparison.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CIRA(EXT)020
Subjects: Acoustics
Acoustics > Underwater Acoustics
Last Modified: 02 Feb 2018 13:18
URI: http://eprintspublications.npl.co.uk/id/eprint/695

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