Ship Track Initiation Of Shipborne High Frequency Surface Wave Radar Based On Tracking Before Detection Method

High frequency surface wave radar（HFSWR）can detect targets beyond visual range by using the characteristics of vertical polarization high-frequency electromagnetic wave diffraction propagation along the sea surface,and has the advantages of long-distance and large-area detection.In addition to the advantages of shore based HFSWR,shipborne HFSWR can also make use of the flexible and mobile characteristics of mobile platform,break through the fixed detection area limitation of shore based HFSWR,and expand its detection range,which has become a hot spot of HFSWR technology research in recent years.Due to the influence of the motion of the ship borne platform,the target tracking and detection method of the shipborne HFSWR is different from that of the shore based HFSWR,and faces many difficulties.Among them,track initiation is the first step and a very important stage of HFSWR target tracking,which directly affects the tracking quality of target track.Combined with the characteristics of shipborne HFSWR,this paper studies the ship target track initiation method of shipborne HFSWR based on tracking before detection.The main contents of this paper are as follows:1.The target track characteristics in the echo spectrum of shipborne HFSWR are studied.Firstly,the effects of ship borne platform motion and first-order sea clutter broadening on target signal in single frame RD spectrum are simulated and analyzed.Then the target motion model and measurement model of shipborne HFSWR are deduced,and the target track characteristics in continuous frames are analyzed through simulation and measured data.The analysis shows that the measured value of target track of shipborne HFSWR has nonlinear variation characteristics;When the ship is anchored,the speed and spindle angle of the platform shake violently,which will aggravate the broadening of the target signal and the fluctuation of the radial speed,lead to the overlapping of the target signal and reduce the correlation of the target;In the navigation state,the target is submerged in the widened sea clutter signal,the target track signal flickers and the signal-to-noise ratio is low,resulting in the difficulty of track initiation.2.A track initiation method for shipborne HFSWR based on DP-TBD is developed.Firstly,the track initiation method based on DP-TBD is applied to shipborne HFSWR,and the target track initiation results are given;Then,in order to solve the problem of false track caused by the jumbled first-order sea clutter strong signal points and target broadening signals,a shorter coherent accumulation time and sliding window time are used in the construction of RDT three-dimensional structure to mitigate the impact of ship borne platform motion on target signal broadening and improve the correlation of target information between frames;Combined with the long-time residence characteristics of shipborne HFSWR target in the range cell and the linear relationship between radial velocity and radial range change rate,a shipborne HFSWR target track initiation method based on improved DP-TBD is developed,which eliminates the false target track and improves the track initiation effect.3.In order to solve the problem of track initiation of weak targets with flickering signals in the widened first-order sea clutter area under the navigation state of ship borne platform,a ship target track initiation method for shipborne HFSWR based on pseudo spectrum is developed.Firstly,the effective effect of using target broadening information to construct pseudo spectrum on multi time target signal accumulation is simulated and analyzed;Then combined with the moving law of the target signal in the range Doppler domain,a ship target track initiation method based on pseudo spectrum is proposed;Combined with the actual situation,the strategy of using low threshold CFAR detection points and pseudo spectral signal accumulation points to confirm the real track is proposed;Finally,it is verified by the measured data of shore based HFSWR and shipborne HFSWR;The verification results show that this method can realize the track initiation of low signal-to-noise ratio（5d B）targets with signal flicker characteristics under the first-order sea clutter.4.Based on the advantages and adaptability of different track initiation methods,this paper presents a target tracking processing flow suitable for shipborne HFSWR.Firstly,the track initiation strategy based on sliding window processing is given in the track initiation stage.In the track maintenance stage,the minimum cost data association method of unified azimuth benchmark is used to complete the target tracking application;Then,the track quality evaluation method based on AIS data is given,and the target tracking results are analyzed and evaluated.The results show that the data processing flow of ship borne ground wave radar target tracking given in this paper has certain applicability,and the target tracking results can be obtained under different motion states of ship borne platform.