An adaptive two stage Kalman structure for passive undersea tracking

A structure has been developed for tracking maneuvering undersea targets when the observations are passive. Inherent in this problem is the ability to smooth the original measurements before the highly nonlinear transformations to range, so that the range estimate will be less biased. Unlike other tracking techniques, the approach offered is to break up the problem into two stages, before and after the range transformation. It is shown by simulation that the structure substantially reduces the range bias while closely following maneuvering sources at varying distances. The exhibited bias reduction and stability is a clear improvement over previous approaches to this particular application