Passive geolocation and tracking of an unknown number of emitters

An algorithm for the geolocation and tracking of an unknown number of ground emitters using the time difference of arrival (TDOA) measurements in practical scenarios is proposed. The focus is on solving the important issue of data association, i.e., deciding from which target, if any, a measurement originated. A previous solution for data association based on the assignment formulation for passive measurement tracking systems relied on solving two assignment problems: an S-dimensional (or SD, where S >= 3) assignment for association across sensors and a 2D assignment for the measurement-to-track association. In this paper, (S + 1)D assignment algorithm-an extension of the SD assignment formulation-that performs the data association in one step, is introduced. It will be shown later that the (S + 1)D assignment formulation reduces the computational cost significantly without compromising tracking accuracy. The incorporation of correlated measurements, as with the case of TDOA measurements, into the SD framework that typically assumes uncorrelated measurements, is also discussed. The nonlinear TDOA equations are posed as an optimization problem and solved using SolvOpt, a nonlinear optimization solver. The interacting multiple model (IMM) estimator is used in conjunction with the unscented Kalman filter (UKF) to track the geolocated emitters.