Estimation of underwater source parameters by use of multipath information

Normal mode theory is used to formulate a multipath ocean channel in terms of a relatively straightforward linear-transfer function matrix. The formulation can be used as a basis for maximum-likelihood and MUSIC-type estimator for source parameters such as depth and range. The Cramer-Rao bound shows that the accuracy of depth estimation depends on the shape of the sound speed profile. It is shown that adapting a MUSIC-type algorithm to the transfer function matrix for the ocean avoids difficulties produced by coherence of multipath arrivals from the same source