Study On Countering Off-board Interference For Radar Seeker Of Anti-ship Missile

Radar seeker is an important guidance system used in anti-ship missile (ASM), thewarfare efficiency of ASM could be directly affected by the anti-jamming performanceof radar seeker. As the electromagnetic environment of sea battlefield is getting morecomplex, the anti-jamming ability of radar seeker is facing a bigger challenge.Therefore, the problems, such as studying the anti-jamming techniques of radar seekerand enhancing its capacity of adapting complex warfare environment, are needed to besolved urgently. And these works would have important signification and applicationvalue in military. This dissertation is dedicated to the anti-jamming technologies ofASM terminal guidance, which would face the typical jamming, such as chaff andoff-board active decoy, during its acquisition and target tracking phase.On the analysis of off-board jamming faced by the radar seeker, the foundationof anti-jamming techniques is proposed by summarizing the chaff, corner reflector andoff-board active jamming. The content of this part is as following:Firstly, the property of chaff echo is analyzed. The tactical application and weaponequipments of dilution and centroid jamming are reviewed. Secondly, the basicproperties of corner reflector, such as effective RCS, directivity and frequency property,are discussed. The typical weapon equipments of corner reflector are also concluded.Finally, the basic principle, usage specialty and typical weapon equipments of off-boardactive jamming are discussed. The development tendency of off-board jamming isanalyzed.On the anti-jamming technologies of radar seekers in acquisition phase, thedetermination of the optimal starting distance of radar seeker, and the target acquisitionstrategy to encounter dilution jamming is deeply studied. By using these approaches, theseeker acquisition performance will be effectively enhanced. The content of this part isas following:①The method of determining the optimal starting distance of radar seeker isproposed in the single target and multiple targets situation respectively. By consideringthe termination error of auto-control flying missile and target scattering error, theoptimal starting distance of radar seeker, which can ensure the given acquisitionprobability, is obtained by simulation in some typical situation based on the model ofacquiring zone. For the multiple targets situation, the expression method of scatteringerror of the formation targets is built based on the formation targets model. The optimalstarting distance of radar seeker for different parameters is then obtained. And thefactors that impact the optimal distance are discussed.②A novel method to eliminate the dilution jamming is introduced based ontarget-object map (TOM), after the analysis of dilution jamming effection on ASM target acquisition. This method, which apply the TOM concept into the ASM targetacquisition phase in the missile defense application, establish the TOM mapping modeland the corresponding target selection rules. It is shown by simulation that the radarseeker can effectively acquire the designated target in the multiple targets situation byusing this method, especially in the condition of chaff dilution jamming.On the anti-jamming method of radar seeker in the tracking phase, severaleffective off-board jamming discrimination methods are proposed for anti-jammingapplication during the target tracking phase of radar seeker. The major work of this partis studied from the points of view of information processing and tech-tact applicationrespectively. The content of this part is as following:①Two countering methods of chaff centroid jamming are introduced based on thedifference of the polarization characteristics of the warship target and the chaff jamming.At the beginning of chaff centroid jamming evolvement, the warship target and thechaff jamming can not be discriminated by radar seeker. The existence of chaffjamming can be determined by using the generalized likelihood ratio test (GLRT). Thenthe centroid jamming can be suppressed through the oblique projection polarizationfilter. The measuring error of target angle of radar seeker can also be reduced throughthis processing. For the situation that these two targets can be discriminated, aneffective jamming discrimination algorithm is designed by consideration the diversityproperties of the polarization angle statistical of the warship target and chaff jamming.This method is testified by simulation and field test.②An INS-aided off-board jamming countering method for radar seeker isproposed using the short-term high accuracy character of inertial navigation system(INS). Based on the analysis of the feasibility of the off-board jamming counteringmethod based on the INS information aiding, an extended Kalman filtering (EKF)algorithm is proposed to reduce the random measuring error of radar seeker and obtainmore accurate estimation of target location and velocity. On the Basis of the GLRTdetection algorithm, an enhanced double-threshold detection method is proposed toeffectively detect the off-board jamming, which can offer the precondition to start-upthe INS information aiding. Its effectiveness is validated by both computer simulationand hardware-in-the-loop simulation.