ASA 124th Meeting New Orleans 1992 October

4aUW2. Effect of bearing errors and random sound-speed fluctuations on a holographic source localization method.

Daniel Rouseff

Robert P. Porter

Appl. Phys. Lab., Univ. of Washington, 1013 NE 40th St., Seattle, WA 98105

A holographic source localization method has recently been proposed by Mourad et al. [J. Acoust. Soc. Am. 92, 1031--1039 (1992)]. The signals from both a reference and an unknown source are measured and combined along a vertical receiving array. To the extent that the two signals travel through the same medium, fluctuations in the sound-speed profile along the common paths approximately cancel thereby reducing the knowledge of the medium required to locate the source. In the present work, the effects on the localization algorithm of bearing errors and random fluctuations such as those caused by internal waves are considered. A 21/2-dimensional formulation featuring adiabatic modes and weak scattering is used in the forward scattering problem. The statistical properties of the predicted source location are examined. The random fluctuations are shown to diminish the amplitude but not the location of the mean focus and also to modify the sidelobe structure. Numerical examples are given. [Work supported by ONR.]