Recognition Of True And False Ballistic Warheads In Midcourse

Ballistic warhead usually releases various baits in middle course tocheat the ballistic warhead defense system of the opposite side,making itdifficult for the defense side to intercept the true warhead. As a result,the recognition of the true ballistic warhead under the interference fromother false targets becomes more and more important in the wholeballistic warhead denfence system. This dissertation focuses on thefeature extraction of midcourse ballistic targets based on wideband andnarrow band radar information, serving for ballistic missile defense inmidcourse.The introduction of background and significance of this research werefirstly given. Then the review and summary of present status of methodsfor the recognition of the ballistic true warhead are presented, followingwhich is the frame work and main content of this dissertation.The Micro-Motion difference of the midcourse targets is the onlyavalibale distiction since the true warhead and other false targets aresimilar in appearance, electromagnetic scattering characteristics andorbital parameters. This paper firstly gives the mechanic analysis of thosemidcourse targets and presents Micro-motions’ mathsmatical models.Owing to the lack of field datas of those targets, the simulations ofthe wideband and narrow band radar echoes of midcourse targetsaccording to their motions with the help of CST electromagneticcomputing software are conducted. Then the precession periodestimation based on the RCS sequence of the midcourse targets isstudied and the compare of cyclic autocorrelation function with Fourier analysis, average autocorrelation function and average magnitudedifference function are conducted to testify the validity of cylicautocorrelation function.What’s more, the Micro-Doppler analysis of the dominent scatteringpoints on the midcourse targets was carried out to extract theinformation about those midcourse targets’s Micro-Motions. The optimallength of the window of Short-Time Fourier Transform (STFT) and PeudoWigner-Ville distribution are detemined with the method proposed inthis paper. And a method based on the minimum entropy of the DopplerSpectrum of radar echoes was developed to cancel out the translationalphase.Since the High Resolution Range Profile(HRRP) reflects thedistribution of the dominant scattering points on the targets, HRRP is asignificant feature for target recognition. This paper presents someattempts to detect the variations of targets’ radial size from HRRP. Thevariations in radial size can be utilized to give an estimate of theMicro-Motion information of those targets. What’s more, the CLEANmethod is also applied to HRRP matching in order to reduce thecomputational complexity greatly.Summary of this dissertation is made and the problems demandingfurther research are pointed out finally.