James A. Doutt
Dept. of AOPE, Woods Hole Oceanographic Inst., Woods Hole, MA 02543
Edward H. Hug
Old Ironsides, Inc., New London, CT 06320
The range and depth of a target are determined and compared with the known depth and the range as derived from differential GPS navigation. The data consists of a single return from a monostatic sonar configuration. The method uses a cost function defined as the sum of the squares of the differences between the arrival times measured from the data and those predicted by ray trace for an assumed target depth and range. The depth and range are then varied so as to minimize the cost function. Only the direct and surface-reflected paths have been used. However, the method is easily generalized to use more arrivals if the bottom depth is known and bottom-interacting arrivals can be identified.