Active matched‐field processing.

In passive matched‐field processing, a model is used to simulate the acoustic field propagating from an object to a receiver array (usually with vertical extent). After generating many replica fields corresponding to many object positions, one can estimate the location of the object by seeing which of these replica fields best matches the received data. In this paper, active matched‐field processing is demonstrated. An acoustic model based on adiabatic normal modes is used to simulate the acoustic field on a vertical receiving array in an active scenario. That is, the acoustic energy from a point source propagates to an object in a three‐dimensional environment, is scattered by the object, and is subsequently received on a vertical array of hydrophones. Just as in the passive case, this model is used to create many replica fields corresponding to many object positions, and then the position of the object is estimated by determining which of these replica fields best matches the received data. In principle, it is also possible to determine the orientation of the object.