【摘要】：相干光通信系統(tǒng)具有較高的接收靈敏度,可實現(xiàn)遠距離和高碼率的數(shù)據(jù)傳輸,是自由空間光通信技術的重要發(fā)展方向。然而,大氣信道中湍流引起的折射率隨機起伏,導致激光信號的振幅和相位發(fā)生隨機波動,降低相干檢測效率,影響通信系統(tǒng)的性能。系統(tǒng)地研究大氣湍流對相干光通信系統(tǒng)性能的影響,探索抑制湍流效應、改善光通信系統(tǒng)性能的方法具有重要的理論意義和應用價值。此外,目前關于湍流對空間相干光通信性能影響的研究主要是基于平面波模型和單端探測方式,平面波模型無法體現(xiàn)光束半徑對系統(tǒng)性能的影響。另外,光相干技術中的平衡探測是改善相干光通信系統(tǒng)性能的新技術。本文將開展基于平衡探測方式下的大氣信道相干光通信系統(tǒng)性能的研究。本文系統(tǒng)地分析了湍流對基于平衡探測方式下的空間相干光通信系統(tǒng)性能的影響,其中信號光和本振光根據(jù)實際情況分別選擇平面波模型和高斯光束模型。得出了在無湍流和有湍流影響下該模型中的信噪比概率密度分布函數(shù)及誤碼率計算表達式。在此基礎上,針對近地水平傳輸鏈路,在無相位補償和采用自適應相位補償兩種條件下,研究了光強閃爍指數(shù)和相位波動方差對系統(tǒng)誤碼率的影響;同時還分析了孔徑平均效應對接收孔徑直徑的最優(yōu)值的影響。數(shù)值計算了星地下行傳輸鏈路,孔徑平均效應和天頂角對系統(tǒng)誤碼率的影響。本文最后基于實際測量的不同天氣下的大氣信道衰減系數(shù),利用Optisystem軟件,對空間相干光通信與非相干光通信系統(tǒng)性能進行了仿真,通過接收端的眼圖分析比較了不同天氣條件下兩種通信方式的接收性能。
[Abstract]:Coherent optical communication system has high receiving sensitivity and can realize long distance and high bit rate data transmission. It is an important development direction of free space optical communication technology. However, the random fluctuation of refractive index caused by turbulence in atmospheric channel leads to random fluctuation of the amplitude and phase of laser signal, which reduces the efficiency of coherent detection and affects the performance of communication system. The effects of atmospheric turbulence on the performance of coherent optical communication systems are systematically studied. It is of great theoretical significance and practical value to explore the methods of suppressing turbulence effects and improving the performance of optical communication systems. In addition, the current research on the effect of turbulence on the performance of spatial coherent optical communication is mainly based on the plane wave model and single-ended detection mode. The plane wave model can not reflect the influence of beam radius on the performance of the system. In addition, balanced detection in optical coherence is a new technique to improve the performance of coherent optical communication system. In this paper, the performance of coherent optical communication system in atmospheric channel based on balanced detection is studied. The effect of turbulence on the performance of spatially coherent optical communication system based on balanced detection is systematically analyzed in this paper. The plane wave model and Gao Si beam model are selected according to the actual conditions of signal light and local oscillator light respectively. The probability density distribution function of signal-to-noise ratio and the expression of bit error rate in the model are obtained without and without the influence of turbulence. On this basis, the effects of intensity scintillation index and phase fluctuation variance on the bit error rate of the system are studied under the condition of no phase compensation and adaptive phase compensation for near-ground horizontal transmission link. At the same time, the influence of average aperture effect on the optimum value of the diameter of the receiving aperture is analyzed. The effects of satellite transmission link, average aperture effect and zenith angle on the bit error rate of the system are numerically calculated. Finally, based on the actual measured attenuation coefficient of atmospheric channel under different weather conditions, the performance of spatial coherent optical communication and incoherent optical communication system is simulated by using Optisystem software. The receiving performance of the two communication modes under different weather conditions is analyzed and compared by the eye diagram of the receiver.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN929.1

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相關碩士學位論文 前1條

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本文編號：2220492