Crossfix errors of directional acoustic sensors in a medium with a constant horizontal velocity gradient

Abstract

An investigation was made of the magnitude of the bearing and distance errors which result from two passive directional acoustic sensors obtaining a crossfix on a target in a medium with a constant horizontal velocity gradient. Results are tabulated in Appendix III. For the conditions considered, the errors were found to be small in relation to the target range but became appreciable in absolute value at very large target ranges. However, with a knowledge of the horizontal velocity gradient, sensor separation, sensor axis orientation, apparent target range, and apparent target bearing the errors could be predicted. Further, by proper sensor orientation, the errors could be minimized.