UACE2017 Proceedings: Challenges in the calibration of marine autonomous acoustic recorders

• Session:
  Underwater acoustic calibration, testing, facilities and standards
• Paper:
  Challenges in the calibration of marine autonomous acoustic recorders
• Author(s):
  Gary Hayman, Stephen P. Robinson, L. Wang, T. Pangerc, J. Ablitt, P.D. Theobald
• Abstract:
  There has been an increasing use of autonomous acoustic recorders for absolute in-situ measurement of sound in the marine environment. The technology has developed rapidly utilising recent improvements in mobile microprocessors and data acquisition systems, and currently there are a number of commercial off-the-shelf units available to the user. Whilst offering the enhanced ability to monitor acoustic signals autonomously for extended periods, such recorder units introduce a number of measurement and calibration challenges in addition to those associated with the calibration of individual hydrophones. In this paper, methodologies are presented for the calibration and characterisation of autonomous recorders to determine the key acoustic performance characteristics, including the absolute system sensitivity as a function of frequency and direction. Consideration is given to effects due to the proximity of the recorder body to the measuring hydrophone on the frequency and directional response of the overall system. The need for enhanced traceability is particularly acute at frequencies below 1 kHz where high-amplitude anthropogenic sources of greatest concern radiate much of their sound energy. A discussion is provided of the EU EMPIR UNAC-LOW project, and how the work described here feeds into a European initiative to provide improved traceability and more robust metrology infrastructure to catch up with the rapidly evolving legislative framework.
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Contact details

• Contact person:
  Mr Stephen Robinson
• e-mail:
  
• Affiliation:
  NPL
• Country:
  United Kingdom