Discrimination Methods For Ballistic Targets Base On Polarization Radar

With the maturing of active and passive jamming,the development of ballistic missile penetration and defence become more and more intense.Various decoys,such as balloon-profile decoys with small volume and light quality,and numerous active decoys with complex modulation,along with warhead constitute a “target cluster” in midcourse and will be great challenges for ballistic missile defense(MD)system.How to recognize the warheads rapidly and efficiently from the “target cluster” in midcourse will be the formidable obstacles for MD systems.“Eliminate false targets” are the basic ideas for target discrimination in midcourse,false targets can be more easily recognized than warhead,also warhead will be easier to find out if most false targets are eliminated.Radars are the main sensors in MD systems.The characteristics of various targets in temporal,frequency,spatial and polarimatric domain measured by radars,are very important to discriminate warhead from other targets.Actually,polarization information can remarkably improve the capabilities of target detection and discrimination of radar in complex electromagnetic environment.By using the information measured by polarimatric radar,based on the idea of “Eliminate false targets”,the discrimination methods for active and passive decoys are researched in this dissertation.And some conclusions are validated by the experiment data of simulation,microwave anechoic chamber measurement,and field measurement.The main contents of this dissertation include:1.Discrimination methods for passive decoys based on spatial-temporal association.Firstly,aiming to dealing with the issue of trajectory interruption during multiple targets tracking in midcourse,based on the “two-body-motion” characteristics,a spatial-temporal association method is proposed,the trajectory information for passive target discrimination will be prepared.Secondly,a method based on differences of release position is presented to recognize passive decoys(especially balloon-profile light decoy),which is very similar with warhead and very difficult to discriminate.Points of intersection are achieved by the temporal retrieve and spatial association of all trajectories.Passive decoys with different release locations relative to warheads and heavy decoys will be found out.The method provides a different way to recognize passive decoys.2.Discrimination methods for active decoys based on polarization differences.For the active decoys with fixed modulation,changed modulation,and full-polarization modulation in polarimatric domain,discrimination methods based on polarization information differences are proposed.Based on the stable polarization characteristics shared by all active decoys produced by one jammer,active decoys withfixed modulation and changed modulation in polarimatric domain,can be discriminated according to echoes polarization ratios(EPR).Probability density function(pdf)of EPR is derived and used to separate active decoys from physical targets,cumulative probabilities will be calculated to detect and discriminate active decoys.For full-polarimetric modulation decoys,a recognition method based on frequency responding characteristics is introduced.Three-step detection-recognition method based on single measurement and multiple measurements is proposed and the recognition threshold is determined by the microwave anechoic chamber measurements.3.Discrimination methods for decoys in complex jamming environment.Recognizing decoys in complex jamming environment is analyzed in this dissertation.For the active decoys recognition problem in existence of noise barrage jamming,with the processing result of polarimatric cancellation,discrimination methods for active decoys based on phase diversity and frequency diversity are introduced.Aiming to confronting collaborative angle deceptive jamming in midcourse,according to the angle measurement differences in both polarization channels,a detection method for dual-source angular glint jamming is presented.Based on the power requirement and cost control of MD radar,many radar systems with the function of transmitting various types of polarization signals,are compared with each other,based on phase diversity,a method used to discriminate active false targets is proposed.Taken use of scientific experimental polarimetric radar,field measurement experiments are designed to verify the robustness and validity of two proposed decoy recognition methods.