Research On Echo’s Characteristics Of Multiple Shipborne High-frequency Over The Horizon Radar

Multiple-shipborne high frequency over the horizon radar combines theadvantages of ground wave over-the-horizon radar and shipborne platform,it has notonly the good properties of the anti-radiation missile,anti-jamming, anti-lowaltitude sudden attack,anti-stealth,but also has good maneuverability as shipborneplatform. It plays a more and more important role in the modern military war andhas wide applications in civil field,such as Sea-state Remote Sensing and oceanengineering. This paper mainly study the influence of six degree-of-freedom motion(pitch,roll,yaw,sway,heave,surge) of warship under stochastic sea surface on theechoes.The information of this paper may put a basis for later detection and trackingof targets and provide simulation data for parameter extraction.Firstly，a mathematical model of transmitter,target and receiver’s motion isestablished,then the dynamic sum of distance formula of six degree-of-freedommotion of war ship is deduced and a concrete analysis of rotating angle size andtranslational displacement of ship,provides basic model for the following processingof signal.Then analyze the signal form of shipborne high frequency over the horizonradar that is commonly adopted: linear frenquency modulation interrupt continuouswave. On the basis of mathematical model of six degree of freedom motion of shipthat is deduced in chapter2,the delay information is substituted into the differencefrequency signal of transmit and receive signals,and carriy on the reductionapproximation.Combines the concrete condition of six degree of freedom motion ofship,the three-dimensional spectrums of pithch,roll,yaw,sway motions of ship atlevel three and five sea state are simulated.2-D FFT method is used to extracte thevelocity and range informations of difference frequency signal of transmit andreceive signals.To analyze the influence on echo’s characteristics of six degree offreedom motion of shipborne high-frequency over the horizon radar,the range andvelocity informations of six degree of freedom motion and uniform motion arecompared.Finally,the generation mechanism and characteristics of sea clutter ofmonostatic radar and bistatic radar are analyzed.Then the simulation model of thebistatic radar sea clutter is established.Combines the mathematical model of sixdegree of freedom motion of ship,the calculation formula of bistatic radar angle andthe random changes part of bistatic radar sea clutter mathematical simulation modelis deduced. Subsequently, the sea clutter spectram at different sea state levels of sixdegree of freedom motion of ship is simulated. By contrasting the sea clutter spectram of six degree of freedom motion and uniform motion of ship,the influenceof six degree of freedom motion of ship on the sea clutter spectram is analysed.