【摘要】：低空監(jiān)視雷達(dá)在對低空目標(biāo)進(jìn)行探測時,由于多徑效應(yīng)的存在,直達(dá)信號與多徑信號同時進(jìn)入天線波束主瓣,兩者矢量疊加,使回波信號幅度和相位發(fā)生改變。同時直達(dá)信號與多徑信號強(qiáng)烈相干,且難以分辨,嚴(yán)重影響了低空監(jiān)視雷達(dá)對目標(biāo)的檢測與跟蹤性能,甚至造成目標(biāo)丟失。因此,如何抑制多徑效應(yīng)對目標(biāo)檢測與跟蹤的影響,對低空監(jiān)視雷達(dá)探測性能的提升非常重要。本文從多徑效應(yīng)這一關(guān)鍵問題出發(fā),通過建立的低空多徑回波幾何模型,研究了直達(dá)信號與多徑信號的幾何關(guān)系。接著分析了影響多徑信號的反射系數(shù)以及多徑陣列信號的回波模型,同時還詳細(xì)介紹了單脈沖測角原理,并分析了多徑下影響目標(biāo)檢測概率與低角跟蹤精度的主要因素。然后,以本文建立的理想平面對稱鏡面反射模型為基礎(chǔ),分析了多徑效應(yīng)對目標(biāo)檢測的影響,還研究了多徑下影響低空目標(biāo)回波信號幅度和功率的主要因素,并推導(dǎo)了低空目標(biāo)回波信號與多徑傳播因子的關(guān)系。接著對多徑下低空監(jiān)視雷達(dá)目標(biāo)檢測方法進(jìn)行了研究,推導(dǎo)并仿真分析了采用頻率分集技術(shù)的多頻M/N檢測器的檢測性能曲線,再通過大量實驗仿真,得出了使多頻M/N檢測器具有最佳檢測性能時所對應(yīng)的M值。接下來,為了降低多徑對低空監(jiān)視雷達(dá)低角跟蹤性能的影響,本文在多徑陣列信號模型的基礎(chǔ)上,通過對天線方向圖進(jìn)行改進(jìn),首先設(shè)計了最優(yōu)對稱差波束,進(jìn)而實現(xiàn)了對稱波束單脈沖測角法。接著通過設(shè)計雙單脈沖的和波束與差波束方向圖,實現(xiàn)了雙零點單脈沖測角法。再分別仿真并驗證了兩種算法對解決多徑下低角跟蹤問題的有效性,同時分析了兩種算法的測角性能。由于以上兩種改進(jìn)的單脈沖測角算法均有各自的優(yōu)缺點及應(yīng)用場景,所以最后本文通過對兩種算法的算法流程、復(fù)雜度以及測角精度進(jìn)行仿真對比分析,給出了不同場景下,對稱波束法與雙零點法的最小SNR與最小可測仰角表。最后總結(jié)并給出了不同的雷達(dá)場景與精度要求情況下,如何選擇合適的低角跟蹤算法,從而達(dá)到節(jié)省資源,提高低空監(jiān)視雷達(dá)低角跟蹤精度的目的,給實際工程提供了理論參考。
[Abstract]:When low altitude surveillance radar is used to detect low altitude target, the direct signal and multipath signal enter the main lobe of antenna beam at the same time because of the multipath effect, the vector superposition of the two signals causes the amplitude and phase of echo signal to change. At the same time, direct signal and multipath signal are strongly coherent and difficult to distinguish, which seriously affects the detection and tracking performance of low altitude surveillance radar, and even results in the loss of target. Therefore, how to suppress the effect of multipath effect on target detection and tracking is very important to improve the detection performance of low altitude surveillance radar. In this paper, based on the key problem of multipath effect, the geometric relationship between direct signal and multipath signal is studied by establishing the geometric model of multipath echo at low altitude. Then the reflection coefficient of the multipath signal and the echo model of the multipath array signal are analyzed. At the same time, the principle of monopulse angle measurement is introduced in detail, and the main factors affecting the target detection probability and the accuracy of low angle tracking under multi-path are also analyzed. Then, based on the ideal plane symmetric mirror reflection model established in this paper, the influence of multipath effect on target detection is analyzed, and the main factors affecting the amplitude and power of echo signal of low altitude target under multi-path are also studied. The relationship between the echo signal of low altitude target and multipath propagation factor is deduced. Then the target detection method of low altitude surveillance radar with multi-path is studied, and the detection performance curve of multi-frequency MN detector using frequency diversity technology is derived and analyzed by simulation, and then a large number of experiments are carried out to simulate the detection performance of the multi-frequency M ~ (N) detector. The M-value corresponding to the optimal detection performance of the multi-frequency M-N detector is obtained. Next, in order to reduce the influence of multipath on the low-angle tracking performance of low-altitude surveillance radar, based on the multipath array signal model, the antenna pattern is improved, and the optimal symmetric difference beam is designed firstly. Then the symmetrical beam monopulse angle measurement method is realized. Then the double-zero monopulse angle measurement method is realized by designing the sum beam and the difference beam pattern of the double monopulse. Then the effectiveness of the two algorithms to solve the problem of low-angle tracking under multi-path is verified and the angle measurement performance of the two algorithms is analyzed. Because the above two improved monopulse angle measurement algorithms have their own advantages and disadvantages and application scenarios, finally, through the simulation and comparison of the algorithm flow, complexity and angle measurement accuracy of the two algorithms, the different scenarios are given. The minimum SNR and minimum measurable elevation table of symmetric beam method and double zero method. Finally, how to select the appropriate low-angle tracking algorithm under different radar scenes and precision requirements is summarized and given, so as to save resources and improve the low-angle tracking accuracy of low-altitude surveillance radar. It provides a theoretical reference for practical engineering.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN957.51

【參考文獻(xiàn)】

相關(guān)期刊論文 前8條

1 馮子昂;胡國平;周豪;師俊朋;;陣列雷達(dá)低角跟蹤技術(shù)分析與展望[J];飛航導(dǎo)彈;2016年03期

2 徐振海;熊子源;宋聃;肖順平;;陣列雷達(dá)雙零點單脈沖低角跟蹤算法[J];國防科技大學(xué)學(xué)報;2015年01期

3 楊勇;王雪松;張文明;肖順平;;多徑環(huán)境下海面低空目標(biāo)檢測技術(shù)研究[J];電波科學(xué)學(xué)報;2011年03期

4 簡濤;何友;蘇峰;曲長文;顧新鋒;;高距離分辨率雷達(dá)目標(biāo)檢測研究現(xiàn)狀與進(jìn)展[J];宇航學(xué)報;2010年12期

5 謝飛;張忠臣;張鵬;李博章;;多徑效應(yīng)對測向誤差的影響[J];電子測量技術(shù);2010年01期

6 李晶;裴亮;曹茂永;郁道銀;;一種用于多徑環(huán)境的超分辨率TOA定位算法[J];電波科學(xué)學(xué)報;2006年05期

7 楊世海,胡衛(wèi)東,萬建偉,周良柱;多徑反射下低空目標(biāo)檢測研究[J];電子與信息學(xué)報;2002年04期

8 張永泰;多徑效應(yīng)與低仰角跟蹤[J];遙測遙控;2000年02期

相關(guān)博士學(xué)位論文 前1條

1 劉俊;米波雷達(dá)低仰角估計方法研究[D];西安電子科技大學(xué);2012年

相關(guān)碩士學(xué)位論文 前1條

1 黎敏;多徑效應(yīng)下相控陣?yán)走_(dá)低空目標(biāo)角度估計與跟蹤技術(shù)研究[D];電子科技大學(xué);2006年

，

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