Altitude Measurement of Low Elevation Target Based on Iterative Subspace Projection

A new temporal-spatial general MUSIC (TS-GMUSIC) method is proposed for the altitude measurement of low-elevation targets. As an expansion of the traditional temporal-spatial process, our proposed method employs the alternate projection (AP) theory to measure the target elevation. Different from conventional AP where the direction vector is iteratively projected to achieve the elevation, we iteratively project the received echoes onto different signal subspace to obtain the elevation. Thus the conventional direction-search of the multiple targets can be simplified into one target parameter estimation. Further we consider the multipath geometry characteristic of low-elevation targets, therefore the direction-search of both direct wave and specular wave is changed into one-dimensional parameter search. The Monte-Carlo simulations prove that the proposed TS-GMUSIC shows better performance than the existing temporal-spatial algorithms. Moreover, the real-data processing of VHF radar demonstrates the validity of the proposed method.