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Analysis of the Radiated Soundfield of a Deep Water Multibeam Echosounder Using a Submerged Navy Hydrophone Array
CCOM/JHC
Multibeam echosounders (MBES) are tools used to gather geophysical information on the seafloor and water column which are important for feature detection, identifying gas seeps, and characterizing the seafloor, among others. At high frequencies (>100Khz), MBES can be calibrated for their ensonification patterns in test tanks. However, deep water MBES feature long transmit arrays and varying geometries that make calibration difficult. In addition, modern systems have higher source levels, broader bandwidths and longer pulse trains that can potentially impact the local soundscape. This study will better characterize the radiated sound field of deep water MBES. A MBES survey was conducted using a Kongsberg EM122 MBES on the SCORE range, a submerged broadband hydrophone array. The collected hydrophone data was analyzed and the radiation pattern was made and compared to theoretical models of the transmit beam pattern. The analysis identified an equipment limitation which prevented the full characterization of the MBES radiation pattern. Despite the limitation, the full radiation pattern revealed the presence of lobe like artifacts in the alongship direction that are atypical and suggest the need for further study and experimentation.
Michael Smith came to CCOM in 2016 as a master’s student in Ocean Engineering/Ocean Mapping with a focus on quantifying the radiation patterns of deep water multibeam echosounders for calibration and impact assessment. Prior to joining the Center, Michael graduated from the University of Rhode Island with a B.S. in Ocean Engineering and a B.A. in Spanish. In addition to pursuing his master's degree, Michael is also an engineer for CCOM—working to develop processing methodologies for seafloor backscatter data collected by multibeam echosounders. Additionally, he continues to expand his work on multibeam sound source verification and assessment.
