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考虑散射链路所在高空大气中温度、压强、臭氧浓度和湍流垂直强度的分布规律,依据Rayleigh散射理论,提出紫外光多径散射链路模型。将散射体划分为多个散射元,各散射元对应一组路径,并依照不同路径划分信号光,计算其信号强度;利用对数正态分布和非直视链路的湍流模型,分别计算不同路径的信号强度概率密度分布;用所有概率密度函数卷积得到接收端各路径信号叠加的强度分布和链路损耗。根据实际大气环境仿真得到:新模型得到的信号强度概率密度分布较原模型更集中,紫外光的消光系数受吸收系数影响显著,二者垂直分布曲线只在15km以下略有差异。在高空2~14km范围内,当收发端位于11km左右闪烁指数存在极大值,而收发端位于6km左右闪烁指数最小。综合考虑湍流效应和链路损耗,高空紫外光通信可将收发端安置于10km高度以下。
Considering the distribution of temperature, pressure, ozone concentration and turbulence vertical intensity in the upper atmosphere of the scattering link, the UV multipath scattering chain model is proposed based on Rayleigh scattering theory. The scatterer is divided into a plurality of scatterers. Each scatterer corresponds to a set of paths, and the signal light is divided according to different paths to calculate the signal intensity. By using the logarithmic normal distribution and the non-direct-view link turbulence model, Path signal strength probability density distribution; using all the probability density function convolution to obtain the receiving end of the path signal superimposed intensity distribution and link loss. According to the actual atmospheric environment simulation, the probability density distribution of the signal intensity obtained by the new model is more concentrated than the original model, and the extinction coefficient of ultraviolet light is significantly affected by the absorption coefficient. The vertical distribution curve of the two models only has a slight difference below 15 km. At a height of 2 ~ 14km, when the sending and receiving end is located at about 11km, there is a maximum value of the scintillation index, while the receiving and sending end is located at a minimum of 6km. Taken into account the turbulence effects and link loss, high-altitude ultraviolet communication can send and receive placed in the 10km height below.