Optimal source localization and tracking from passive array measurements

If the signal of a moving source is observed at several spatially separated locations during a common time interval, the received signals exhibit differential delays and Doppler shifts which provide information about source location and velocity. This paper deals with the optimal (in the minimum mean-square error sense) source localization and tracking by utilizing differential delay and Doppler observations at a linear array of receivers. We shall be concerned with source ranges large compared with array baseline and with the distance traversed by the source during the observation interval. It is shown that the optimal estimation procedure can be carried out in two sequential steps without any loss in performance. In the first step source location is estimated from the differential delay group of measurements. In the second step source velocity is estimated from the differential Doppler group of measurements and the outcome of the first step. Furthermore, by employing an intermediate track-dependent parameter set, the two-step algorithm yields a closed form solution of the estimation problem.