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A Modeling and Analytic Method of Radar Sea Echo Based on CHMM |
Wan Jian-wei; Yang Jun-ling |
College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China |
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Abstract When high resolution radar observes rough sea surface with low grazing angle the level of sea clutter increases obviously and the sea spike phenomena appears. It is not accurate to analyze the radar echo including stationary sea clutter, spike and target with the conventional statistical model based on single Probability Density Function (PDF). In this paper, the Continuous Hidden Markov Model (CHMM) is used to model and analyze the sea clutter. The echoes from sea surface are divided into three states of CHMM stationary sea clutter, sea spike and target. The Gaussian Mixture Density Model (GMDM) and the Baum-Welch algorithm are used to construct the PDF expressions of the observations of the three states and re-estimate the CHMM parameters, respectively. At the same time, the expressing of the observation-state joint probability is modified to avoid the underflow of the denominator during the iterative procedure of the GMDM parameters. Thus, a new method is proposed for modeling and analyzing sea clutter.
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Received: 21 April 2006
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