【作者】 司立宏；

【导师】 敖发良；

【作者基本信息】 桂林电子科技大学 ， 通信与信息系统， 2007， 硕士

【摘要】 本文着重分析了海水和大气信道对蓝绿激光上行通信的影响,深入研究了激光通过风浪作用下的随机起伏海面的上行传输特性。在前人研究海浪谱以及随机海浪数学模型的基础上,模拟随机起伏的海面及其特征参数,并首次利用这种模型来分析随机起伏的海面对上行激光通信的影响。按照光束分割的思想,将发射光束在随机起伏海面上的光传输简化为确定传输方向的光在确定倾斜角的海面上的光传输。通过水池实验,将随机起伏的海面模型与斯涅尔定律相结合,分析并计算激光束通过随机起伏的海面和长距离的大气传输后,到达接收机所在的平面时形成的光斑的具体参数。通过理论分析和计算机仿真,发现海面随机起伏对上行通信的影响取决于海面光斑的相对尺度,光束随着海面的起伏在有限的范围内不断漂移,相当于做随机扫描,结合有效的扫描机制可以保证通信质量;还发现海面的随机起伏还使得上下行信道更加不对称。大气的折射率是不均匀分布的,光束在大气中传输时发生弯曲和偏移,可以根据折射率模型和光束的偏移量对光斑参数进行修正。论文理论分析、计算机仿真和实际实验相结合,相互印证,得出很多重要的结论,对深入研究上行激光通信和实际系统的设计有重要的意义。更多还原

【Abstract】 The influences of sea and air on blue-green uplink laser communication are analyzed emphatically, and the characteristics of laser transmission upward through the random undulate sea surface caused by wind waves are studied deeply. Based on the existing studies of sea wave spectrum and the mathematical models of random sea waves, the fluctuation in waves and feature parameters of the sea surface are simulated, and the sea wave model is used for analyzing effects of the random undulation of sea surface to uplink laser communication for the first time. According to the thought of beam division, the complex problem that beam propagation through stochastic fluctuant sea is simplified to a simple problem that ray with certain direction goes through an inclined surface with certain tilt angle. By the tank experiment, combining the model of random fluctuant surface with Snell’s Law, specific parameters of the spot formed at the receiver plane after beam going through the stochastic fluctuant sea surface and a long distance of atmosphere are analyzed and calculated. By theoretical analysis and computer simulation, the author finds out that the influences of sea’s random undulation lie on the relative scale of spot formed at the sea surface. Beam wanders in a limited area with the fluctuation of sea surface constantly, that behave as random scanning. Cooperated with effective scanning mechanism, quality of communication can be ensured. Also the random undulation of the sea surface aggravates the asymmetry of uplink and downlink. The refractive index of air distributes unevenly, so beam will be curved and deviate from the initial position during propagation through the atmosphere. According to the model of air index and analysis of beam offset, parameters of spot formed at the receiver plane can be amended in theory. In the paper theoretical analysis and computer simulation are discussed, combining with practical experiments, many important conclusions are educed, which have great significance in research on uplink laser communication and design of operational system.更多还原