本文選題：Bragg散射頻率 + 高階累積量��； 參考：《哈爾濱工業(yè)大學》2014年碩士論文

【摘要】：本文針對高頻雷達天發(fā)岸收模式下一階海雜波的特性與抑制這一問題進行了深入分析和仿真研究，其中分別從模型建立和信號處理兩個角度，重點研究了新模式下一階海雜波的展寬特性、統(tǒng)計特性、散射截面積特性以及結(jié)合雜波特性的級聯(lián)抑制問題。 針對一階海雜波的展寬特性問題，首先分析了一階海雜波的空間分布特性，從理論和仿真角度證明了在回波延時固定的條件下，其分布可以用一個橢圓來描述，并據(jù)此進一步得到了Bragg散射頻率的計算公式。此外，考慮到雜波單元內(nèi)雙基地角變化所導致的一階海雜波展寬現(xiàn)象，定量計算了由雙基地角所引起展寬的空間分布情況。由仿真結(jié)果可以看出，其展寬程度隨著接收波束方位角的增大而減少。而關于電離層的非線性相徑擾動和多徑現(xiàn)象所引起的一階海雜波展寬問題，本文結(jié)合了電離層的粗糙面模型對不同層所引起展寬程度分別進行了計算。結(jié)果表明，電離層引起的展寬主要與積累時間、發(fā)射波束寬度、電離層相關距離等參數(shù)有關。 隨后，對一階海雜波幅度統(tǒng)計特性的檢驗問題，本文采用計算高階累計量的方法，將一個高斯檢驗問題轉(zhuǎn)化為一個二元假設問題。首先，基于最大后驗概率準則對一階海雜波進行了分段，得到了一段近似平穩(wěn)的回波數(shù)據(jù)，并且對分段后的數(shù)據(jù)進行了AR模型參數(shù)估計，結(jié)合AR模型參數(shù)以及多個距離門的平穩(wěn)回波數(shù)據(jù)，構(gòu)建三階、四階累積量的協(xié)方差矩陣并計算檢驗統(tǒng)計量，結(jié)果表明，，在置信概率為95%的門限下，多個距離門回波數(shù)據(jù)的檢驗結(jié)果服從高斯分布。 關于一階海雜波的散射截面積特性，本文首先推導得到了電離層為球面分層、電子濃度服從準拋物線模型條件下色散系數(shù)的計算公式，仿真分析了電離層色散效應對高頻窄帶信號傳播的影響，從匹配濾波角度研究了電離層對距離分辨率的作用，從而進一步得到了其對實際雜波分辨單元的影響，隨后以限制雜波單元為參考對實際雜波單元進行了劃分，結(jié)合Gill提出的雙基地散射截面積計算公式，仿真分析了在考慮電離層對雜波分辨單元影響下的一階海雜波散射截面積。 為了對展寬的一階海雜波進行抑制，本文從實際雜波回波信號成分入手，提出了一種基于EMD分解以及雜波對消的級聯(lián)抑制處理方案。由算法仿真結(jié)果可以看出，EMD分解可以有效提取出展寬的一階海雜波分量，從而為相徑擾動函數(shù)的提取提供基礎，考慮到銳化后的回波譜一階海雜波仍然占優(yōu)，本文隨后結(jié)合雜波多維特性，提出了一種基于FBLP的雜波對消方法，由對消結(jié)果可以看出，一階海雜波得到了抑制，并且可以有效的檢測到目標信號。
[Abstract]:In this paper, the characteristics and suppression of the first order sea clutter under the high-frequency radar landing mode are analyzed and simulated, respectively from the point of view of model building and signal processing. In this paper, the broadening characteristics, statistical characteristics, scattering cross-sectional characteristics and cascaded suppression of first-order sea clutter under the new model are studied. Aiming at the broadening characteristics of first-order sea clutter, the spatial distribution characteristics of first-order sea clutter are analyzed, and the theoretical and simulation results show that the distribution of first-order sea clutter can be described by an ellipse under the condition of fixed echo delay. Furthermore, the formula of Bragg scattering frequency is obtained. In addition, considering the first order sea clutter broadening caused by bistatic angle variation in clutter unit, the spatial distribution caused by bistatic angle broadening is calculated quantitatively. The simulation results show that the broadening degree decreases with the increase of the azimuth of the receiving beam. For the first order sea clutter caused by nonlinear phase diameter disturbances and multipath phenomena in the ionosphere, the degree of broadening caused by the ionospheric rough surface model is calculated separately. The results show that the ionospheric broadening is mainly related to the accumulation time, the emission beam width and the ionospheric correlation distance. Then, in order to test the statistical properties of first-order sea clutter amplitude, a Gao Si test problem is transformed into a binary hypothesis problem by using the method of calculating high-order cumulants. Firstly, the first order sea clutter is segmented based on the maximum a posteriori probability criterion, and an approximate stationary echo data is obtained, and the AR model parameters of the segmented data are estimated. Based on AR model parameters and stationary echo data of multiple distance gates, the covariance matrix of third and fourth order cumulants is constructed and the test statistics are calculated. The results show that the confidence probability is 95%. The test results of multiple distance gate echo data are obtained from the Gao Si distribution. With regard to the scattering cross-sectional characteristics of first-order sea clutter, a formula for calculating the dispersion coefficient of ionosphere with spherical stratification and electron concentration under quasi-parabola model is first derived in this paper. The effect of ionospheric dispersion on the propagation of high frequency narrowband signal is simulated and analyzed. The effect of ionosphere on range resolution is studied from the point of view of matched filtering, and the effect of ionospheric dispersion on the real clutter resolution unit is obtained. Then, the actual clutter element is divided with the limited clutter element as the reference. Combined with Gill's bistatic scattering cross section calculation formula, the first order sea clutter cross section area considering the influence of the ionosphere on the clutter resolution unit is simulated and analyzed. In order to suppress the first order sea clutter, a concatenated suppression scheme based on EMD decomposition and clutter cancellation is proposed. The simulation results show that the EMD decomposition can effectively extract the first order sea clutter component, which provides the basis for the extraction of phase path perturbation function, considering that the first order sea clutter is still dominant after sharpening the echo spectrum. In this paper, a new clutter cancellation method based on FBLP is proposed. The results show that the first-order sea clutter is suppressed and the target signal can be detected effectively.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN958.93

【參考文獻】

相關期刊論文 前10條

1 種衍文,黃天錫,趙正予,謝樹果;HF信道的色散帶寬及其對脈沖波傳播的影響[J];電波科學學報;2001年03期

2 吳雄斌;尹微;程豐;柯亨玉;;寬波束高頻雷達海洋回波的統(tǒng)計特性[J];電波科學學報;2006年03期

3 焦培南;楊龍泉;凡俊梅;;短波天波反射/地波繞射組合新傳播模式及其可能應用[J];電波科學學報;2007年05期

4 丁宗華;陳春;;電離層色散效應對線極化雷達信號的影響分析[J];電波科學學報;2011年01期

5 姜維;鄧維波;楊強;;高頻超視距混合天地波雷達海雜波特點分析[J];電子與信息學報;2011年08期

6 楊龍泉;凡俊梅;蔚娜;李星;焦培南;李吉寧;;天波/地波組合傳播模式下一階海雜波特性分析[J];電波科學學報;2012年04期

7 楊龍泉;焦培南;凡俊梅;;短波天波/地波聯(lián)合傳播模式下定位方法研究[J];中國電子科學研究院學報;2010年03期

8 趙志國;陳建文;鮑拯;翁海超;;OTHR海雜波抑制典型方法綜合性能評估[J];武漢理工大學學報(交通科學與工程版);2012年06期

9 陳俊斌,盧琨,劉興釗;天波雷達短駐留時間下海雜波抑制的改進算法[J];上海交通大學學報;2004年S1期

10 張忠,袁業(yè)術,孟憲德;Constrained-MUSIC算法在高頻地波艦載超視距雷達中的應用[J];系統(tǒng)工程與電子技術;2002年05期

相關博士學位論文 前1條

1 張雅斌;高頻地波雷達干擾與海雜波信號處理研究[D];西安電子科技大學;2010年

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