Design of an automated, computer-controlled acoustic tank facility and its application to measurement of nonlinear effects

Abstract

A computer-actuated acoustic research tank facility designed for facilitating precise acoustic measurement of sonar transducers, small arrays, and structural models has been installed at the Georgia Institute of Technology. The apparatus consists of a wooden tank, having dimensions of 7-m diameter and 5-m depth, integrated to a computer actuated positioning and data retrieval system. A resident minicomputer controls positioning and signal generation, as well as providing temporary data storage and signal processing capabilities. Permanent data storage and post-processing are provided by a remote minicomputer. The multiaxial positioning and scanning system, which extends over the entire active tank area, provides accurate triaxial and rotational positioning of the transducer. Component hardware, positioning system design features, computer software and facility capabilities are presented. One current use for the facility is to perform a series of experimental measurements exploring nonlinear effects encountered in sound beams generated by a high-power transducer operating at a moderately high ka value. Waveforms are measured at a variety of locations in the near and farfields, both on and off axis. Signal processing then provides amplitude and phase information for the fundamental and higher harmonics.