Dynamic DOA Estimation Error Correction for Shipborne HFSWR Under 6-DOF Motion

Under the influence of the six-degree-of-freedom (6-DOF) motion of the platform, the direction of arrival (DOA) estimation accuracy of the shipborne high-frequency surface wave radar (HFSWR) is significantly reduced. Existing research mostly focuses on the steering vector deviation caused by the positional changes of the array elements, often ignoring the phase disturbance caused by the relative velocity differences of these elements. In this paper, we establish the array motion model and echo model under the 6-DOF motion coupling of the platform. The influence of position changes and relative velocity differences of the array elements on the DOA estimation error is systematically analyzed, and the dynamic steering vector, including the phase disturbance term of the relative velocity differences, is innovatively derived. The dynamic steering vector of the shipborne HFSWR array can be embedded in various DOA estimation methods to achieve dynamic compensation for phase deviation caused by platform motion, thereby correcting the DOA estimation error accurately. Both simulation and field data experiments verify the effectiveness of the proposed dynamic steering vector-based method compared to traditional digital beamforming (DBF) and multiple signal classification (MUSIC) methods. The results show that the proposed method can significantly reduce the DOA estimation error under the influence of 6-DOF motion of the platform.