Research On Coordinatre Registration And Multipath Data Process Of Shipborne High Frequency Hybrid Sky-Surface Wave Radar

Shipborne High Frequency(HF)Hybrid Sky-surface Wave Radar uses sky waves and surface waves to detect targets and the data measured by radars is usually ray distance,Doppler velocity and azimuth angle.In order to obtain real positions and motion information of targets in the geographic coordinate,it is necessary to convert targets' measurement vectors in radar coordinate to state vectors in geographic coordinate,and this conversion process is called Coordinate Registration(CR).Due to the existence of sky-wave paths in this type of radar,ionosphere's stratification will lead to multipath effects,that is,there will be multiple measurements corresponding to one target at the same time.The multipath effect will adversely affect CR and probability data association.The main work of this dissertation can be summarized as follows:1.Studied the CR problem of targets.The ray tracing method and the geographic method are used to coordinate targets,and the key P-D conversion coefficients are derived.For the method of geometric models,the coordinate registration formulas based on the plane measurement model and the spherical model are derived separately,and accuracy of these formulas is verified by simulation experiments.Then,the measuring error theory and Geometric Dilution of Precision is used to analyze CR errors and location precision.2.Researched target state estimation algorithms in this type of radar.A target tracking model is built,and some nonlinear filtering algorithms are analyzed.The Jacobian matrix of measurement transfer matrix is given,and a simulation target is tracked and filtered by three filtering algorithms.The filtering results are compared and analyzed.3.Analyzed radio waves' propagation pattern recognition,and multipath probability data association algorithms.A Viterbi algorithm based on Hidden Markov Model is used to study coordinate registration problems under multipath conditions.Simulation experiments are used to illustrate multipath-measurements.Propagation modes of radio waves are modeled as hidden states,and measurements are modeled as observation states.The Viterbi algorithm is used to decode propagation modes,and the Root-Mean-Square-Errors of target positioning after propagation mode recognition are given.MPDA algorithm is applied to solve the multipath probability data association problem with known ionosphere height,and MPCR algorithm is used to solve the same problem with unknown ionosphere height.