Passive Localization: A Model-Base Approach

Passive localization by use of propagation models, sometimes called 'Matched Field Processing' is usually carried out in three steps. First some appropriate model is selected, then model parameters (usually taken from archival data or from auxiliary measurements) are introduced into the model. Finally acoustic measurements of the field radiated by the source to be located are made---which, in combination with the properly parameterized model, allow a solution for the source coordinates to be carried out. Here we use such a model-based approach in conjunction with a normal-mode model. By coupling the procedure with a parameter estimation/identification scheme and using a horizontal (towed) array instead of the usual vertical array, we show that the model parameters need not be known a priori in order to carry out the solution. This is in contrast to the standard approach in which the modal functions and wavenumber must be a priori known in order to solve the problem; sufficient information to determine the range of the source can be inferred directly from the measured data themselves. Using a sophisticated acoustic propagation model to generate simulated data, coupled with various array processing techniques, the feasibility of the approach is demonstrated. The essential problems associated withmore » the technique are found to be the need for a large aperture for sufficiently accurate wavenumber estimation, and the need for a general sensitivity study in order to evaluate the efficiency of the algorithm. 16 refs., 11 figs., 1 tab.« less