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  本文關鍵詞： 雷達 MIMO OTH 空間分集　出處：《電子科技大學》2014年碩士論文　論文類型：學位論文

【摘要】：多輸入多輸出(MIMO)系統(tǒng)利用空間分布的多個發(fā)射天線和多個接收天線獲得空間分集增益,從而用來對抗信道衰弱。天波超視距(OTH)雷達利用電離層折射探測目標,具有超遠距離目標探測和信息獲取的能力,具有重大的戰(zhàn)略意義,本文針對采用MIMO技術的OTH雷達(MIMO-OTH雷達),研究復雜環(huán)境中MIMO-OTH雷達目標檢測的分集增益,分析雷達系統(tǒng)參數(shù)配置、多徑傳播等因素對MIMO-OTH雷達系統(tǒng)目標檢測性能的影響。通過分析OTH雷達的工作模式和OTH雷達信號在電離層中的傳播特點,構建同時具有MIMO雷達以及OTH雷達特性的MIMO-OTH雷達回波信號模型,該信號模型不僅體現(xiàn)雷達信號在復雜電離層環(huán)境中的傳播特性,還能體現(xiàn)多徑傳播現(xiàn)象,在有加性復高斯白噪聲和雜波的情況下,根據(jù)上述MIMO-OTH雷達回波信號模型,利用尼曼-皮爾遜(NP)準則得到高斯檢測器。本文研究了NP準則下MIMO-OTH雷達最佳檢測器的漏檢概率,同時推導了MIMO-OTH雷達目標檢測的分集增益,并以分集增益為評價指標分析了影響MIMO-OTH雷達檢測性能的主要因素。雷達信號經過電離層傳播后照射到目標,并在目標上反射后再次經過電離層傳播回到雷達接收端,因此在本文所構建的信號模型中存在兩次電離層傳播和一次目標反射過程,其中電離層傳播損耗系數(shù)和目標反射系數(shù)有可能是確定未知量或者復高斯隨機變量,使得總的信道增益表現(xiàn)為復高斯、復雙高斯或復三高斯等隨機變量。本文將分別計算在復雙高斯信道環(huán)境下和復三高斯信道環(huán)境下MIMO-OTH雷達目標檢測的分集增益。對于一個由M個發(fā)射天線和N個接收天線所構成的MIMO-OTH雷達,若第m個發(fā)射天線發(fā)射的探測信號通過mQ條傳播路徑照射到目標,經目標反射后通過mnH條傳播路徑被第n個接收天線接收到,本文證明在復高斯或復三高斯信道環(huán)境中,雷達系統(tǒng)目標檢測能夠獲得的最大分集增益d滿足1 1min{, }N M n m mn md NM H Q= =￡ ? ? 。研究表明MIMO-OTH雷達目標檢測的分集增益小于等于雷達收發(fā)端天線個數(shù)的乘積與總傳播路徑條數(shù)的最小值。增加天線個數(shù)或者多徑條數(shù)均可以增大分集增益,有利于雷達提高檢測性能,本文的分析不僅表明天波MIMO-OTH雷達較傳統(tǒng)OTH雷達具有更好的檢測性能,并且為合理設計MIMO-OTH雷達的系統(tǒng)參數(shù)以提高目標檢測性能提供了理論參考。本文最后分別對兩種復雜環(huán)境下MIMO-OTH雷達目標檢測的進行數(shù)值仿真,展現(xiàn)了不同場景下MIMO-OTH雷達目標檢測的漏檢概率情況,同時分析對比了不同雷達參數(shù)、不同信道環(huán)境以及不同傳播路徑條數(shù)對雷達目標檢測性能的影響。
[Abstract]:Multiple input and multiple output (Mimo) systems use spatially distributed multiple transmit antennas and multiple receiving antennas to gain spatial diversity gain to counter channel debility.Sky wave over-the-horizon OTHradar uses ionospheric refraction to detect targets. This paper studies the diversity gain of OTH radar and MIMO-OTH radar based on MIMO technology, and analyzes the configuration of radar system parameters. The effects of multipath propagation on the target detection performance of MIMO-OTH radar system are analyzed. The working mode of OTH radar and the propagation characteristics of OTH radar signal in the ionosphere are analyzed. The echo signal model of MIMO-OTH radar with the characteristics of MIMO radar and OTH radar is constructed. The signal model not only reflects the propagation characteristics of radar signal in complex ionospheric environment, but also reflects the phenomenon of multipath propagation. In the case of additive complex Gao Si white noise and clutter, according to the above mentioned MIMO-OTH radar echo signal model, we use the Niman-Pearson MIMO-OTH criterion to obtain the Gao Si detector. In this paper, we study the missed detection probability of the best MIMO-OTH radar detector under NP criterion. At the same time, the diversity gain of MIMO-OTH radar target detection is deduced, and the main factors affecting the detection performance of MIMO-OTH radar are analyzed with diversity gain as the evaluation index. The radar signal is irradiated to the target after ionospheric propagation. After reflection on the target, the ionosphere propagates back to the radar receiver again, so there are two ionospheric propagation and one target reflection process in the signal model constructed in this paper. Among them, the ionospheric propagation loss coefficient and the target reflection coefficient may be unknown variables or complex Gao Si random variables, so that the total channel gain is represented by complex Gao Si. In this paper, we calculate the diversity gain of MIMO-OTH radar target detection in the environment of complex double Gao Si channel and complex triple Gao Si channel, respectively. For a MIMO-OTH radar target detection by M transmitting antenna and N connection, we will calculate the diversity gain of target detection in the condition of complex double Gao Si or complex triple Gao Si, respectively. MIMO-OTH radar composed of receiving antenna, If the detection signal transmitted by the m transmitting antenna reaches the target through the mQ propagation path and is received by the nth receiving antenna by the mnH propagating path after the reflection of the target, it is proved in this paper that in the environment of the complex Gao Si or the complex triple Gao Si channel, The maximum diversity gain d obtained by radar system target detection satisfies 11 min {,} NM n m mn m m d NM H Q = =? ? It is shown that the diversity gain of MIMO-OTH radar target detection is less than the minimum value of the product of the number of antennas at the radar transceiver end and the number of total propagation path bars. Increasing the number of antennas or the number of multi-path bars can increase the diversity gain. The analysis of this paper not only shows that the sky-wave MIMO-OTH radar has better detection performance than the traditional OTH radar, It provides a theoretical reference for reasonably designing the system parameters of MIMO-OTH radar to improve the performance of target detection. Finally, numerical simulation of MIMO-OTH radar target detection in two complex environments is carried out. The missed detection probability of MIMO-OTH radar target detection in different scenes is presented. The effects of different radar parameters, different channel environment and different propagation path number on radar target detection performance are analyzed and compared.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN958

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本文編號：1534855