Source localization in underwater acoustic channels using random or deterministic signals

Work concerning depth and range, estimation accuracy in a multipath environment is presented. Cramer-Rao bounds are presented for location parameter accuracy and their dependence on the velocity profile is discussed. It is shown that significant variations of the velocity profile have only minor effects on the resulting bounds. It is also shown that an unknown parameter in the velocity profile has little effect on attainable accuracy. This indicates the possibility of calibrating the velocity profile using only the target data. The authors present computer simulations of a maximum likelihood estimator for source depth which comes close to the Cramer-Rao bound when the velocity profile is known, but fails badly when the postulated profile is inaccurate and no attempt at calibration is made