EM122

Kilo Moana 2012 Sea Acceptance Report

CruiseID: 
KM1212

The EM122 and EM710 systems both appear to be configured correctly and, for the most part, adequately calibrated. Small MRU roll alignment residuals do exist and it is recommended that these be confirmed as soon as possible through acquisition of a pair of reciprocal survey lines over a flat and featureless seafloor. Verification lines should have been run for calibration tests for both systems, however, time constraints on the cruise schedule precluded this. It is standard practice to run verification lines.

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 2012 Quality Assurance Report

CruiseID: 
KM1204

The point of the QAT visit was to help the host institution in developing protocols and practices that are conducive to the acquisition of high quality multibeam data. Even with a finely tuned and calibrated survey system, it is still possible to collect poor quality data through poor choice of operational system parameters, etc. Software tools to aid in this regard were deployed and documentation was prepared that can help return the system to a healthy configuration such that the institution can recover from a sub-optimal system configuration.

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.

Syndicate content