Utilizing an Extended Target for High Frequency Multi-beam Sonar Intensity Calibration

TitleUtilizing an Extended Target for High Frequency Multi-beam Sonar Intensity Calibration
Publication TypeThesis
Year2014
AuthorsHeaton, J
Degree and ProgramMaster of Science in Mechanical Engineering
Number of Pages75
Date Published09/2014
UniversityUniversity of New Hampshire
LocationDurham, NH
Keywordsacoustics, calibration

There exists an interest in expediting intensity calibration procedures for Multi-Beam Echo-Sounders (MBES) to be used for acoustic backscatter measurements. Current calibration methods are time-consuming and complicated, utilizing a target that is different from the seafloor. A target of irregularly oriented chain links arranged in a 'curtain' was constructed to simulate an extended surface, like the seafloor. Tests with a 200-kHz SIMRAD EK60 Split-Beam Echo-Sounder (SBES) to investigate the targets scattering strength were performed. These tests suggest that the scattering strength depends on the number of scattering elements. A 200 kHz Reson SeaBat T20-P MBES was calibrated with the same target. This MBES was rotated so that all beams were incident on the target. The final output is a beam-dependent calibration coefficient determined from the sonar equation. The T20-P was then used to collect backscatter in the field along a local survey line, where data were compared to the EK60.