Ship Target DOA Estimation Based On Shipborne High Frequency Surface Wave Radar Simulation

High-frequency surface wave radar(HFSWR)operate with vertically polarized electromagnetic waves to enable all-weather,over-the-horizon monitoring of ship targets.Shipborne HFSWR offer better prospects for development as they can be flexibly deployed to areas of interest for target detection.The limited size of the shipborne platform requires the deployment of a miniaturized array antenna,and the diminished aperture caused by the miniaturized antenna leads to a lower azimuthal resolution of the ship target.In addition,due to sea clutter interference and the sixdegree-of-freedom(DOF)motion with the movement of the shipborne platform,both of which are detrimental to the estimation of the target’s azimuth.Therefore,there is a need to investigate the above-mentioned problems of shipborne HFSWR ship target azimuth estimation,as follows:1.In order to solve the problem of poor azimuthal resolution of shipborne HFSWR,the synthetic virtual array algorithm is proposed.The algorithm establishes the corresponding synthetic virtual array model,and uses the movement of the antenna in the spatial position to expand the array aperture equivalently.After deriving the target echo signal model,the ship target azimuth information is obtained based on digital beam forming(DBF)and multiple signal classification(MUSIC)algorithms,respectively.The simulation results verify that the application of the synthetic virtual array technology to shipborne platforms can improve the accuracy of ship target azimuth estimation.2.To address the sea clutter spreading problem caused by the forward motion of the shipborne platform,the loading sample matrix inversion(LSMI)algorithm is applied to the sea clutter suppression in shipborne HFSWR.The method first transforms the data into the array-Doppler domain with the transformation matrix and achieves data downscaling.Then the optimal weight vector is obtained by the LSMI algorithm.Finally,the array signal is multiplied with the optimal weight vector to accomplish the purpose of sea clutter suppression.The experimental results show that the LSMI algorithm can effectively suppress the sea clutter and achieve ship target detection.3.The forward motion of the shipborne platform and the six DOF motion cause the target point to spread and shift in the spectrum,which makes it difficult to confirm the azimuth information of the ship target.Aiming at the above problems,this paper quantitatively analyzes the factors influencing the platform motion on the target azimuth estimation based on the shipborne platform motion models.Through simulation experiments,it is verified that yaw and forward motion are the key factors affecting the azimuth estimation of the ship target.4.A MUSIC synthetic virtual array algorithm based on Bayesian inference is proposed for the ship target azimuth estimation problem in the case of unknown coherent target echoes.Firstly,the array signal model is reconstructed.Then,Bayesian inference is applied to obtain the ship target number.Finally,based on the estimated ship target number,the MUSIC synthetic virtual array algorithm is applied to effectively discriminate the direction of arrival(DOA)of the target.The simulation results show that the proposed algorithm can effectively extract the ship target azimuth information.