Modeling And Simulation Of The Land And Sea Clutter And Study On The Techniques Of Target Detection

The dissertation is focused on the modeling and simulation of coastal clutter as well as radar target detection.Chapter 1 introduces the main problem of current modeling and simulation of the sea clutter and radar target detection techniques and proposes the solution.In chapter 2, a physical realizable filter that adopts minimum phase feature and complex cepstrum technology is presented. The method of generating general random clutters sequences is described in detail. The relationship between the classical clutter models and GC-PDF model is also analyzed which deduces the method of least mean squares parameter estimation. Furthermore, a new model parameter estimation algorithm is brought out through the parameter decoupling and fully using the information contained in the clutter sequences. This new estimation method translates four dimension nonlinear optimization problem to one dimension linear optimization problem, which can not only improve the estimation performance, but also depress the calculation quantity and the necessarily clutter sample numbers. The simulation is processed and the results prove the validity and veracity of the method proposed in this chapter.Chapter 3 proposes a novel coastal compound distributed model of the clutter amplitude. Then the technique of generating the random coastal compound clutter sequences is presented with deduction of the nonlinear relation of autocorrelation function between the coastal compound clutter random sequences and the correlated Gaussian random sequences based on the research on the statistic characteristic, which is the important precondition for the clutter simulation based on the ZMNL. In the end, a new approach is presented with WVD based on the signal detection in the ocean whereas WVD has the time-frequency local characteristic for LFM signal. The simulation result with the observed data shows veracity and validity for the clutter mode and significant clutter suppression with the detection algorithm.In chapter 4, the chaos basic theories are studied and the methods to define chaotic time series are analyzed at first. Then, two prediction technologies based on the RBF neural networks and memory-based predictor are analyzed with their performance comparation, which gives the analytical results. By adopting the model of fractional Brownian motion (FBM), the Hurst exponent is deduced based on the observed data of the S band radar. Furthermore, the fractal dimension of the S-band sea clutter is also deduced. Then the largest Lyapunov exponent is obtained by Rosenstein method, which proves its chaos and fractal characteristic. It turns out to be a novel method of chaotic time series prediction based on LS-SVM. Based on the observed data of S-band radar, the computer simulation is processed and the results prove the validity and veracity of the conclusion proposed in chapter 4.In chapter 5, the pattern classification method of SVM is analyzed with an ameliorated RBF kernel function, contrasted whose classification performance with those of FKNN and FMMNN. By analyzing the box dimension difference between the observed sea clutter and the target echo signal, the method of target detection is proposed based the fractal property of the sea clutter. Also by adopting the SVM classifiers of the ameliorated RBF kernel function, a novel method of target detection in the background of sea clutter is presented based on the predictive information difference between the observed sea clutter and the target echo signal. Based on the observed data, the computer simulation is processed and the results prove the effective detection performance and noise tolerance.In chapter 6, a discrete model is set up for high resolution profile of an extended target, and then the math model of echo signal is presented from an extended target produced by stepped chirp radar. The effect of target motion on a range profile is analyzed in deep, and then precision necessitation is derived for motion compensation. Studies on the method of time field correlation and the rule based on the least burst error; the motion compensation arithmetic is presented which suits the project requirement. Finally the result of a cyber-emulation proves the conclusion.Chapter 7 is the summary of the paper and points out the problems which need further research.