OPTIMIZATION OF HYDROPHONE PLACEMENT FOR ACOUSTIC ARRAYS USING SIMULATED ANNEALING

The simulated annealing technique of nonlinear optimization [S. Kirkpatrick, C. D. Gellatt, Jr., and M. P. Vecchi, Science 220, 671-680 (1983)] is applied to optimization of horizontal and vertical sonar receiver array configurations. Optimizations of horizontal planar arrays to minimize array noise gain in a 2-D isotropic noise field result in regular geometric arrangements of the array elements. Performance measures are then formulated for arbitrary 3-D array configurations using either plane-wave beamforming or linear matched-field beamforming. These measures, which are based on normal-mode modeling of average array signal and noise responses, are applied first to optimization of plane-wave-beamformed vertical arrays. The optimized vertical-array configurations exhibit less regularity of spacing than do the horizontal arrays, because of the complexity of the acoustic field in the vertical. The results can be interpreted as a compromise between placement of hydrophones at depths with high signal-to-noise ratio and separation of hydrophones to reduce the array noise gain. Examples are given for optimization for matched-field processing based on minimization of average array noise power or average sidelobe power.