RANGE AND DEPTH ESTIMATION USING A VERTICAL ARRAY IN A CORRELATED MULTIPATH ENVIRONMENT

This paper investigates the effects of correlation between time differ ence of arrival (TDOA) estimates on the localization of an underwater source in a direct-surface reflected propagation environment. The inve stigation is for a two-element vertical array with omnidirectional sen sors. Expressions for the covariance matrix of the noisy TDOAs are der ived. The results show that the estimated TDOAs are correlated and tha t the degree of correlation depends on the relative location of the so urce. The expressions for variances of range and depth estimators have been developed using a least squares technique. The results show that the expressions for variances of the range and depth estimators can b e in error by as much as a factor 3.3 if the correlation among the TDO As is ignored. The expressions for the covariances of the TDOAs and th e expressions for the variances of the range and depth, which incorpor ate the correlation in the TDOAs, are corroborated with Monte Carlo si mulations.