本文關(guān)鍵詞： 地雜波 實(shí)測(cè)SAR圖像 幅度分布特性 空間相關(guān)性 雜波仿真　出處：《西安電子科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：在進(jìn)行復(fù)雜環(huán)境中目標(biāo)的檢測(cè)和識(shí)別時(shí),雷達(dá)接收到的回波信號(hào)中不僅包含目標(biāo)的信息,同時(shí)也包含了目標(biāo)所處地面環(huán)境的散射回波,即地雜波。雷達(dá)目標(biāo)環(huán)境的復(fù)雜多變性,決定了地雜波對(duì)于雷達(dá)目標(biāo)探測(cè)的重要意義,為了提高目標(biāo)識(shí)別的準(zhǔn)確性,必須對(duì)特定的地雜波特性進(jìn)行分析和研究,才能夠有效的抑制雜波。論文結(jié)合實(shí)際背景的需求,基于實(shí)測(cè)農(nóng)田和水泥的合成孔徑雷達(dá)(SAR)圖像,深入分析了其地雜波的統(tǒng)計(jì)分布特性和空間相關(guān)性。論文主要工作如下:1.分別從地海雜波的實(shí)驗(yàn)測(cè)量、基于雜波散射機(jī)理的后向散射以及基于統(tǒng)計(jì)的雜波仿真三個(gè)方面,總結(jié)闡述了國(guó)內(nèi)外目前對(duì)雜波的研究現(xiàn)狀以及發(fā)展趨勢(shì)。2.討論了地雜波的雷達(dá)散射機(jī)理以及影響雷達(dá)散射截面的條件,闡述了幾種常用的地面環(huán)境電磁散射分析的數(shù)值方法和解析方法。介紹了瑞利分布、對(duì)數(shù)正態(tài)分布、韋伯爾分布、K分布四種統(tǒng)計(jì)分布模型,給出了四種模型的概率密度隨分布參數(shù)的變化情況,并列出各個(gè)分布函數(shù)相應(yīng)的參數(shù)估計(jì)的方法。3.讀取得到實(shí)測(cè)圖像的數(shù)據(jù),對(duì)所獲得的數(shù)據(jù)進(jìn)行統(tǒng)計(jì)分析,并且經(jīng)過(guò)參數(shù)估計(jì)算法得到各個(gè)統(tǒng)計(jì)模型的分布參數(shù),將各個(gè)經(jīng)驗(yàn)?zāi)Ｐ偷母怕拭芏扰c原始圖像的幅度分布概率密度進(jìn)行擬合。學(xué)習(xí)了兩種經(jīng)常用到的擬合優(yōu)度檢驗(yàn)方法:K-S檢驗(yàn)和卡方檢驗(yàn)方法。并用K-S檢驗(yàn)方法對(duì)擬合進(jìn)行檢驗(yàn),得到了對(duì)數(shù)正態(tài)分布模型為最優(yōu)模型。根據(jù)圖像數(shù)據(jù)的相關(guān)性,分析了雜波數(shù)據(jù)的空間相關(guān)性。4.比較了兩種典型的雜波模擬方法,即零記憶非線性變換法(ZMNL)和球不變隨機(jī)過(guò)程法(SIRP)的優(yōu)缺點(diǎn)。闡述了仿真過(guò)程中高斯白噪聲的生成以及濾波器的獲取方法。根據(jù)估計(jì)得到的分布參數(shù),用對(duì)數(shù)正態(tài)分布(Log-normal)分布的ZMNL仿真方法,仿真得到農(nóng)田雜波和水泥雜波的分布圖,并將仿真得到的雜波圖的概率密度分布與原始圖像的對(duì)比。給出了通過(guò)ZMNL仿真方法仿真得到的雜波回波數(shù)據(jù)。5.通過(guò)對(duì)合成孔徑雷達(dá)的基本理論的學(xué)習(xí),對(duì)比了兩種經(jīng)典的成像算法線性調(diào)頻算法和距離多普勒成像算法,結(jié)合仿真得到的雜波回波數(shù)據(jù),采用距離-多普勒成像算法對(duì)雜波仿真結(jié)果進(jìn)行成像。并將成像結(jié)果與原始圖像以及雜波仿真圖進(jìn)行重構(gòu)對(duì)比。
[Abstract]:In the detection and recognition of target in complex environment, the echo signal received by radar contains not only the information of the target, but also the scattering echo of the ground environment of the target, that is, the ground clutter and the complex variability of the radar target environment. The importance of ground clutter for radar target detection is determined. In order to improve the accuracy of target recognition, it is necessary to analyze and study the specific ground clutter characteristics in order to suppress clutter effectively. Based on the measured synthetic Aperture Radar (SAR) images of farmland and cement, the statistical distribution characteristics and spatial correlation of ground clutter are analyzed in depth. The main work of this paper is as follows: 1. Backscattering based on clutter scattering mechanism and clutter simulation based on statistics. The research status and development trend of clutter at home and abroad are summarized. 2. The radar scattering mechanism of ground clutter and the conditions affecting radar cross section are discussed. In this paper, several numerical and analytical methods for electromagnetic scattering analysis in ground environment are described. Four statistical distribution models, Rayleigh distribution, logarithmic normal distribution and Webster distribution K distribution, are introduced. The variation of probability density with distribution parameters of four models is given, and the methods of parameter estimation for each distribution function are listed. 3. The data obtained from the measured images are read and the obtained data are analyzed statistically. And through the parameter estimation algorithm, the distribution parameters of each statistical model are obtained. The probability density of each empirical model is fitted to the probability density of the amplitude distribution of the original image. Two commonly used methods of goodness of fit test: K-S test and chi-square test are studied. The fitting is tested by K-S test method. The logarithmic normal distribution model is obtained as the optimal model. According to the correlation of image data, the spatial correlation of clutter data is analyzed. 4. Two typical clutter simulation methods are compared. The advantages and disadvantages of ZMNL (Zero memory nonlinear Transformation) and SIRP (spherical Invariant Stochastic process) are discussed. The generation of Gao Si white noise and the acquisition of filters in the simulation process are described. According to the estimated distribution parameters, Using the ZMNL simulation method of log-normal distribution, the distribution maps of farmland clutter and cement clutter are obtained by simulation. The probability density distribution of the simulated clutter is compared with the original image. The clutter echo data. 5. The basic theory of synthetic Aperture Radar (SAR) is studied. Two classical imaging algorithms, linear frequency modulation (LFM) algorithm and range Doppler imaging algorithm, are compared. The range Doppler imaging algorithm is used to image the clutter simulation results, and the imaging results are compared with the original images and the clutter simulation images.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN957.52

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本文編號(hào)：1538561