Target Elevation Estimation Under Strong Interference with a Deep-Sea Vector Vertical Array

To address the performance degradation of target elevation estimation for deep-sea vector hydrophone vertical arrays under strong interference, this paper proposes an inverse beamforming (IBF)-based interference suppression method for such vertical arrays. The proposed method exploits the array spatial response characteristics to detect, reconstruct, and iteratively cancel dominant interference components. An adaptive stopping strategy is adopted to prevent excessive cancellation and reduce the risk of target self-cancellation. Furthermore, it utilizes the coherence properties between multiple physical channels to perform joint processing of sound pressure and particle velocity channels, thereby enhancing the target-direction response and mitigating residual interference. To alleviate the performance degradation induced by array element failures, this paper introduces a least-squares-based array output reconstruction method to restore the spatial sampling structure and reduce array-manifold distortion. Simulation and sea trial results demonstrate that, compared with conventional beamforming (CBF) and minimum variance distortionless response (MVDR), the proposed method effectively suppresses strong directional interference and recovers the target-direction spatial response. The median spatial-spectrum contrast between the target region and the interference region improves from −1.21 dB before IBF to 2.70 dB after IBF, with a median improvement of 4.12 dB over the full observation interval. The mean estimated elevation angle is 46.5°, close to the reference value of 47.2°, with an RMSE of 0.76° and a success rate of 100% within ±2° and ±3° tolerances. These results indicate that the proposed method enables reliable target elevation estimation under strong interference and remains effective in the presence of array element failures, demonstrating its suitability for practical underwater applications.