Altitude estimation of maneuvering targets in mimo over-the-horizon radar

Target altitude estimation is an important problem in over-the-horizon radar (OTHR) systems for target tracking and classification. Narrow signal bandwidth and rich propagation environment in OTHR render this problem difficult and challenging. In this paper, we develop a novel technique that allows accurate altitude estimation for a maneuvering target during its ascending or descending flight. The proposed technique considers a multiple-input multiple-output (MIMO) OTHR platform and utilizes the difference in the Doppler signatures generated in a micro-multipath propagation environment. The separability of the multi-component Doppler signatures in the time-frequency domain is used to individually estimate the elevation angles of these paths, which are otherwise infeasible to obtain, due to their small angular separation. The estimated elevation angle information is then used to achieve a reliable estimate of the target altitude.