Non-collinear Wave-front Curvature Range Measurement

"Improvements in wave front curvature (WFC) techniques to account for non-collinear sensor placements will decrease acquisition costs associated with submarine WFC ranging systems. Because the number and placement of sensors is not constrained to becollinear, improved target localization coverage and accuracy is achievable at reduced cost. This work will specifically develop time difference of arrival (TDOA) estimation algorithms using generalized cross correlators, matched filters and leading edgedetectors. Target localization algorithms will be developed that estimate the target's range, bearing and depression elevation angle based on the TDOAs measured from non-collinear sensor pairs. The localization algorithms will consider the number of sensorplacements as well as varying sound speed profiles and inexact knowledge of the hydrophone postions when processing the TDOAs to determine target range, bearing and depression/elevation angle. A laboratory simulation will be developed to test theperformance of the TDOA and target localization estimation algorithms. Finally, a sensitivity analysis will be peformed using monte carlo methods to determine target localization accuracy as a function of target geometry, TDOA accuracy, number ofhydrophones and hydrophone spacing/geometry. The use of TDOA estimation for localization of moving objects has been successfully utilized in systems such as GPS and LORAN. It is expected that the successful