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Research On Electronic Countermeasures And Target Detection To Synthetic Aperture Radar

Posted on:2007-10-05Degree:DoctorType:Dissertation
Country:ChinaCandidate:R B GanFull Text:PDF
GTID:1118360185956748Subject:Signal and Information Processing
Abstract/Summary:PDF Full Text Request
As an important military scout instrumentality, synthetic aperture radar plays a more and more important role in modern wars. Research on SAR jamming and SAR de-jamming has become a significant project. And also SAR target detection under jamming has become a significant project in radar areas. Under this background, our aim is to solve the target detection problems of SAR under jamming. The main contents of this paper include SAR imaging and pretreatment, jamming and anti-jamming, target detection under jamming.Firstly, SAR imaging technologies are studied. Deconvolution autofocus algorithm and minimum total variation autofocus algorithm are presented. The performances of the algorithms are studied by experiments. The results show that our algorithms are better than phase gradient autofocus when dealing with second order phase error.Secondly, the author summarizes the statistic characteristic of SAR images as the foundation of SAR image filtering and targets detection. Adaptive windowing based on distribution characteristic algorithms for filtering is put forward. It is compared with statistic window filtering and adaptive windowing based on speckle model. Experiments show that our algorithm has better performance in character preservation of point like targets. This benefits target detection after filtering.After that, basic methods of radar jamming and anti-jamming are introduced. The advantages and disadvantages of SAR jamming and anti-jamming are pointed out, and the study directions of SAR jamming and anti-jamming are got. When jamming, the author brings forward random delay rebound jamming technology, random delay response jamming technology, and fast algorithm of deception jamming. When anti-jamming, the author brings forward rebound jamming cancellation technologies from Doppler frequency domain (including increase pulse repeat frequency and part frequency band imaging), two channels cancellation rebound jamming technologies, and response jamming depression by limiter after range compression. The advantages and disadvantages of the technologies are studied and validated by simulation experiments.Finally, target detection in SAR images is studied. First, Target detection algorithms are studied on the condition of no jamming. Distribution characteristics based target detection algorithms are got at different assumption of distribution. Then the author studied the distribution of SAR images after noise jamming. Detection algorithm, based on general likelihood ratio test and distribution of target and background, is put forward. Experiments show that our algorithm has better performance than traditional CFAR detection algorithm. Target change detection algorithms between two jammed SAR images are studied. Two detection algorithms are brought forward. One is based on confidence interval, and the other is based on general likelihood ratio test. Experiments show that the two algorithms are suitable for target detection in jammed SAR images.
Keywords/Search Tags:synthetic aperture radar, jamming, electronic countermeasure, target detection, general likelihood ratio test
PDF Full Text Request
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