Kilo Moana 2015 Acoustic Test Report

Multibeam System: 
EM122

Executive Summary

Conclusions

  • The EM 122 receive array had a bad preamplifier board that was causing the entire array to have higher noise levels and to exhibit non-uniform distribution of noise characteristics.2.The EM 122 receive array module 6 was out of phase with the rest of the sonar receive array.
  • The EM 122 receive array module 6 was out of phase with the rest of the sonar receive array.
  • Propeller cavitation performance was good and consistent with previous results.
  • Following a modification to the bad preamplifier board, acoustic levels of the EM 122 sonar were considered acceptable and similar to levels measured in 2012.
  • Following a temporary phase shift of module 6 to correct the phase deficiency, sonar operations were good and will allow for good science data acquisition
  • Noise from diesel engines was determined to not be the source of excessive sonar noise.
  • A sewage room rattle was detected and should be corrected when possible.

Recommendations

  • Replace bad sonar preamplifier board.
  • Ensure all sonar modules are in phase with each other.
  • DOCUMENT all temporary fixes to the sonar so future operations issues are easier to diagnose.
  • Correct rattle in sewage room.
  • Install a permanent acoustic monitoring system to allow for shipboard personnel to listen to reference hydrophone data and to acquire and analyze this data during real time operations

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KILO MOANA ACOUSTIC TRIAL AUG 2015-reduced.pdf3.73 MB