Research On Ship Target Detection Methods Of Shipborne Surface Wave Over-the-horizon Radar Based On STAP

Shipborne HFSWR not only has the characteristics of shore-based HFSWR,but also has the advantages of flexible maneuverability and further expansion of the detection range.With the operation of the shipboard platform,the shipboard HFSWR is able to conduct real-time monitoring and surveillance of any area of the sea.Therefore,shipboard HFSWR has become an indispensable technology in the field of marine remote sensing.Due to the broadening of the shipboard first-order sea clutter caused by the movement of the shipboard platform,and the broadening range increases with the speed of the shipboard platform,a large number of target points are located in the broadened first-order sea clutter.As a result,the output signal-to-clutter of the target points is relatively low,making it impossible to perform accurate target detection.In view of this problem,this paper firstly carries out the analysis of the characteristics of shipborne first-order sea clutter and the analysis of the impact of broadened sea clutter on ship targets.Then,dimension reduction the space-time adaptive processing(STAP)method(including space-time cascade and space-time joint methods)are developed to suppress widened first-order sea clutter.Finally,adaptive target detection method is used to carry out target detection and target azimuth measurement on the data after sea clutter suppression.The main works of this paper are as follows:1.The article first analyzes the generation mechanism of the first-order sea clutter.On this basis,first-order sea clutter models based on time domain and frequency domain are established respectively,and the sea clutter broadening and amplitude characteristics under various conditions were analyzed through simulation.In addition,in order to analyze the influence of broadened first-order sea clutter on the target,the target model based on time-domain simulation was established.Finally,the paper analyzes the impact of simulated and measured shipborne sea clutter data on target detection in detail,and finds that the broadened sea clutter reduces the detection performance of the target,which is not conducive to target detection.2.In order to reduce the detection performance of widened sea clutter,the widened sea clutter should be suppressed before detection.Therefore,the paper proposes the time-domain processing and then space-domain adaptive processing method(mDT method for short)suitable for shipborne HFSWR first-order sea clutter suppression.In order to improve the output signal-to-clutter ratio(SCR)of the target after the firstorder sea clutter suppression,an improved mDT method(mDTI for short)method is proposed,which uses the modified sample matrix inversion(MSMI)statistics are output as the results of shipboard sea clutter suppression.Finally,the results of simulated and measured shipborne data show that the suppression result of mDTI method is obviously better than that of mDT method,among which the average mDTI sea clutter output SCR is about 13.37 dB higher than mDT.3.Aiming at the problem of widened sea clutter affecting target detection,an improved joint domain localized(JDL)method is proposed in this paper to suppress the widened sea clutter.This method can effectively suppress the remaining clutter after the clutter suppression of the main channel and improve the convergence speed.It overcomes the problem that the traditional JDL method cannot effectively suppress the remaining clutter after the main channel clutter suppression and the convergence speed is slow during the suppression process,which results in the performance of the method to suppress the sea clutter suppression.Through the results of simulated and the measured shipborne data show that the suppression result of the improved joint domain localized(IJDL)method is obviously better than that of JDL method,among which the average IJDL sea clutter output SCR is about 11.5dB higher than JDL.4.Comprehensive evaluation and analysis of different sea clutter suppression methods are carried out,and then an adaptive target detection method based on sea clutter suppression is developed.Finally,the scheme of target detection and azimuth estimation in the sea clutter is given,and the effectiveness of the scheme is verified by simulated data,measured shipboard data and synchronous ship automatic identification system(AIS)data.