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RV Bat Galim 2016 Acoustic Test Report

During the at-sea test on BAT GALIM, the main objective was to determine ship acoustic characteristics and to assess potential impacts to sonar performance from all acoustic sources. The primary sonars of interest were the newly installed Kongsberg EM 302 and EM 2040 multibeam systems. The following evaluations were accomplished as part this testing:
  1. The overall noise levels of BAT GALIM were measured and characterized with special test sensors and internal noise routines inherent in the Kongsberg sonars.
  2. Propeller cavitation characteristics were assessed.

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.

Optimizing Sonar Performance by Managing Acoustics

Presentation given at the 2014 INMARTECH Meeting in Corvallis, Oregon in November, 2014.

Highlights:
Typical Sources of Acoustic Noise:

  • Machinery Noise
  • Sonar Interference
  • Electronic Noise
  • Propeller Cavitation (Hub and Tip Vortex)
  • Hydrodynamic Flow Noise
  • Appendage Cavitation
  • Transients
  • Bubble Sweepdown

Why Acoustic Noise is Important:

  • Excessive ship-related noise can degrade sonar performance
  • Degraded sonar performance will impact quality of acquired sonar data

Healy 2014 Acoustic Test Report

Gates Acoustic Services was tasked by SCRIPPS Institute of Oceanography to investigate and quantify acoustic issues associated with operation of the USCGC HEALY (WAGBG20). An at-sea investigation was accomplished during ship operations in deep water out of Nome, Alaska on August 13-24, 2014.

Sikuliaq 2014 Acoustic Test Report

Gates Acoustic Services was tasked by University of Alaska, Fairbanks, to investigate and quantify acoustic issues associated with operation of the R/V SIKULIAQ. An at-sea investigation was accomplished during ship operations in deep water out of San Juan, Puerto Rico on September 12-18, 2014.

Kilo Moana 2012 Acoustic Test Report

KILO MOANA’s acoustic signature was higher than previous acoustical data due to electronic noise interference. The levels in the EM 122 sonar operational frequency of 12 kHz were also higher than historic data. A significant problem was noted with numerous elements of the EM 122 sonar array that is believed to be associated with electronic background noise. Electronic noise was determined to be the major deficiency during this acoustic trial.

Kilo Moana 2010 Acoustic Test Report

KILO MOANA’s acoustic signature was comparable to previous acoustical data with one noted exception. The levels in the EM 122 sonar operational frequency of 12 kHz were similar to historic data. A new problem was discovered that was associated with engine and switching room air handler cooling systems. This problem created 4,000 Hz harmonics from the fundamental up through 80 kHz (the limit of onboard instrumentation). An additional problem was noted with numerous elements of the EM 122 sonar array that is believed to be associated with electronic background noise.

Melville 2012 Acoustic Test Report

R/V MELVILLE acoustic signature was successfully measured during this acoustic test. The levels of the EM 122 were controlled by a combination of propeller and anti-roll tank transients.

The general acoustic levels of MELVILLE were good and should produce excellent bathymetric data results:

  • At low speeds (up to 8 knots) sonar levels were controlled by a combination of sea-state and local machinery
  • At mid speeds (8 to 10 knots) sonar levels were controlled by hydrodynamic flow noise

Atlantis 2011 Acoustic Test Report

The acoustic signature of R/V ATLANTIS was successfully measured during this acoustic test. The levels of the EM 122 were controlled by a combination of flow noise and gondola cavitation. Higher sea state data was also influenced by bubble sweepdown effects.

The general acoustic levels of ATLANTIS with the new gondola mounted EM 122 sonar system were good and should produce excellent bathymetric data results:

  • At low speeds (from DIW to 350 RPM), sonar levels were controlled by a combination of sea‐state and local machinery. 

Langseth 2011 Acoustic Test Report

R/V MARCUS G. LANGSETH’s acoustic signature was successfully measured during this acoustic test. The levels of the EM 122 were controlled by propeller cavitation. The quietest vessel condition/speed was when the controllable pitch propellers were set to 85 percent pitch with an engine speed of 600 RPM. This yielded a ship speed of 10 knots and a sonar level of 52 dB. The seismic system created high levels when it was operating.

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