Ambiguity structure of multipath channels

Using a recently proposed definition, the authors characterize the ambiguity function of the multipath underwater acoustic channel for passive localization. They study the impact of two factors not considered by previous definitions: uncertainty about the signal spectrum and existence of multiple paths between the source and the receiver. The importance of accurate channel modeling is addressed by comparing the ambiguity surfaces of methods that use a complete model of the channel and methods that rely only on the information contained in the spatial structure of the incoming wavefield. It is shown that the difference in global behavior can be explained by a virtual array, whose geometry is determined by the set of temporal interpath delays