Abstract:

Considering tracking the three-dimensional (3D) trajectory of an aircraft with high-nearly constant altitude by two 2D passive radars. On the basis of the characteristics of passive radars, a method is proposed to decouple and estimate the target altitude and the horizontal state (target position, speed, etc.) to realize 3D tracking through two parallel estimators. As to the altitude estimator, the altitude interval of a target is divided into a number of altitude sub-intervals, then the weight of the target in each altitude sub-interval is calculated recursively based on the measurement values, and finally a weighted summation method for all altitude sub-intervals is used to obtain the target altitude. As to the horizontal state estimator, the maneuverability of the target in the horizontal plane is further considered, and an interactive multiple model extended Kalman filter (IMM-EKF) is used to update the target horizontal state in combination with the target altitude estimation value. Simulation and experimental results show that the two 2D passive radars can achieve accurate 3D tracking for an aircraft with nearly constant altitude, providing an altitude estimation within 200 m accuracy for a horizontally maneuvering target, and eliminate the error caused by the regardless of the target's altitude in 2D tracking condition.

Key words: 3D target tracking, passive radar, altitude estimation, interactive multiple models