發(fā)布時(shí)間：2018-07-26 13:29

【摘要】：機(jī)載氣象雷達(dá)是民航飛機(jī)上強(qiáng)制安裝的機(jī)載電子設(shè)備，相當(dāng)于飛機(jī)的“雙眼”，可實(shí)時(shí)地探測飛行路徑上存在的暴雨、湍流和風(fēng)切變區(qū)域，給飛行員提供氣象預(yù)警和安全的飛行路徑。機(jī)載氣象雷達(dá)對氣象目標(biāo)的探測是經(jīng)過一系列復(fù)雜的信號(hào)和數(shù)據(jù)處理過程實(shí)現(xiàn)的，信號(hào)處理單元是決定機(jī)載氣象雷達(dá)系統(tǒng)性能的重要部件。論文針對機(jī)載氣象雷達(dá)信號(hào)處理若干關(guān)鍵技術(shù)進(jìn)行了研究，主要工作總結(jié)如下。 1.論文比較了兩種常見的仿真方法，基于回波統(tǒng)計(jì)特性和基于氣象目標(biāo)微物理特性的方法，并提出了一種結(jié)合機(jī)載快速存取記錄器數(shù)據(jù)的全飛行階段機(jī)載氣象雷達(dá)回波仿真方案。 2.機(jī)載氣象雷達(dá)是通過對回波的多普勒處理實(shí)現(xiàn)雨區(qū)探測、湍流和風(fēng)切變的檢測的,即估計(jì)回波的三個(gè)譜矩：功率、平均多普勒頻率和譜寬�，F(xiàn)今氣象雷達(dá)系統(tǒng)中廣泛采用的是非參數(shù)化的脈沖對方法，但不適用于信噪比低的情況和多高斯譜疊加的情況。論文充分利用氣象雷達(dá)回波服從高斯譜這一特性，構(gòu)造參數(shù)化的估計(jì)模型解決這一問題。首先，建立了回波的頻譜、自相關(guān)函數(shù)和協(xié)方差矩陣的數(shù)學(xué)模型。針對低信噪比時(shí)的譜矩估計(jì)，論文在分析協(xié)方差矩陣特性的基礎(chǔ)上，推廣了正弦信號(hào)譜估計(jì)中的子空間和Capon方法，提出了三種參數(shù)化譜矩估計(jì)方法，通過在譜寬和平均頻率上的二維搜索來得到估計(jì)值。針對多高斯譜混合時(shí)的譜矩估計(jì)，論文基于最小二乘擬合思想構(gòu)造代價(jià)函數(shù)，提出了基于頻譜和自相關(guān)函數(shù)擬合的譜矩估計(jì)方法，求解時(shí)通過循環(huán)優(yōu)化思想解決多高斯譜回波混合時(shí)的譜矩估計(jì)問題。最后，通過蒙特卡羅仿真實(shí)驗(yàn)對方法性能進(jìn)行驗(yàn)證。論文還提出了譜矩估計(jì)的快速計(jì)算方法，將估計(jì)時(shí)的二維搜索轉(zhuǎn)化為兩個(gè)一維搜索，可降低運(yùn)算量。 3.地雜波是對機(jī)載氣象雷達(dá)檢測目標(biāo)最大的影響因素。論文分析了氣象目標(biāo)回波和地雜波在頻域的特征，提出了基于譜寬的地雜波抑制方法。利用實(shí)際數(shù)據(jù)進(jìn)行了處理，并從抑制后的回波強(qiáng)度和頻譜特性變化上分析了算法的性能，分析證明提出的方法能夠有效抑制地雜波。
[Abstract]:Airborne weather radar is a compulsory installation of airborne electronic equipment on civil aviation aircraft, equivalent to the "eyes" of the aircraft, which can detect the rainstorm, turbulence and windshear areas in the flight path in real time. Provide pilots with weather warning and safe flight paths. The detection of meteorological targets by airborne meteorological radar is realized through a series of complex signal and data processing processes. Signal processing unit is an important component to determine the performance of airborne meteorological radar system. Some key technologies of airborne meteorological radar signal processing are studied in this paper. The main work is summarized as follows. 1. In this paper, two common simulation methods are compared, one is based on echo statistics and the other is based on the microphysical characteristics of meteorological target. A simulation scheme of airborne meteorological radar echo in the whole flight phase combining with airborne fast access recorder data is proposed. 2. Airborne weather radar detects rain area turbulence and wind shear by Doppler processing of echo namely estimating three spectral moments of echo: power average Doppler frequency and spectrum width. The non-parameterized pulse pair method is widely used in meteorological radar systems, but it is not suitable for the cases of low signal-to-noise ratio (SNR) and multi-Gao Si spectrum superposition. In this paper, a parameterized estimation model is constructed to solve this problem by making full use of the characteristic of meteorological radar echo from Gao Si spectrum. Firstly, the mathematical models of spectrum, autocorrelation function and covariance matrix of echo are established. Based on the analysis of the characteristics of covariance matrix, this paper generalizes the subspace and Capon method of sinusoidal signal spectrum estimation, and proposes three parameterized spectral moment estimation methods for low signal-to-noise ratio (SNR). The estimated value is obtained by a two-dimensional search on the spectral width and the average frequency. In this paper, the cost function is constructed based on the least square fitting idea, and a spectral moment estimation method based on the fitting of spectrum and autocorrelation function is proposed for the estimation of spectral moments when multiple Gao Si spectra are mixed. The problem of estimation of spectral moments when multiple Gao Si spectral echoes are mixed is solved by cyclic optimization. Finally, the performance of the method is verified by Monte Carlo simulation. In this paper, a fast calculation method of spectral moment estimation is proposed, which converts the two-dimensional search into two one-dimensional search, which can reduce the computation cost. Ground clutter is the most important factor affecting airborne meteorological radar detection. In this paper, the characteristics of meteorological target echo and ground clutter in frequency domain are analyzed, and a method of ground clutter suppression based on spectrum width is proposed. The performance of the algorithm is analyzed from the change of echo intensity and spectrum characteristic after suppression, and it is proved that the proposed method can suppress ground clutter effectively.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN957.51

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