Evaluating the performance of underwater acoustic arrays for multi-angle swath bathymetry applications

Transducer array performance is widely recognized as a significant factor in determining the accuracy of target detection and bottom imaging in sonar systems. This thesis proposes methods to evaluate the performance of multi-element acoustic arrays used in a multi-angle swath bathymetry sonar system. The evaluation of array performance is accomplished through measurements of beam pat terns, t he inter-element spacing, and crosstalk between array elements. The Beam Pattern Measurement System developed by the Underwater Research Lab is used to produce beam patterns from which the inter-element spacing is estimated by applying the inverse Fourier Transform. The crosstalk between array elements is investigated by exciting a single element and measuring the phase and magnitude of induced signals on non-excited array elements. A coupling matrix is constructed from measurements and used to predict the impact of crosstalk on the beam pattern and angle-of-arrival estimation with some limitations. The techniques developed to evaluate array performance are applied to three arrays and the results are presented in this thesis.