兰州地区夜间光强起伏特性实验  

Experimental Investigation on Light Intensity Fluctuation at Night in Lanzhou Area

作　　者：王惠琴[1] 李源[1] 胡秋[1] 包仲贤[1] 曹明华[1] WANG Hui-qin, LI Yuan, HU Qiu, BAO Zhong-xian, CAO Ming-hua(School of Com puter~ Communication, Lanzhou University of Technology, Lanzhou 730050, Chin)

机构地区：[1]兰州理工大学计算机与通信学院,兰州730050

出　　处：《光子学报》2018年第4期188-195,共8页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.61465007;61265003);兰州理工大学博士基金(No.14-0232)资助~~

摘　　要：在兰州地区夜间进行了链路长为610m的激光传输实验,研究了晴、阴、沙尘、雨夹雪天气下光强起伏的统计特性.采用闪烁法测量了不同天气下的大气折射率结构常数C_n^2,分析其最大值、最小值、均值和标准差,得到实验期间C_n^2值的范围为1.06×10^(-15) m^(-2/3)~1.05×10^(-13) m^(-2/3),均属于中等湍流;而且晴天和雨夹雪天气下C_n^2值以及起伏程度均大于阴天和沙尘天的值.同时,利用实测光强值分析了Rytov方差,结果表明:晴、雨夹雪、沙尘天气下光强起伏大部分时间属于弱起伏,有小部分时间跨入中等起伏区,而阴天下光强起伏均属于弱起伏,且晴天和雨夹雪天气下光强起伏大于阴天和沙尘天.通过对光强频数分布进行对数正态、Gamma-Gamma和指数威布尔非线性拟合,不同天气下光强起伏概率分布最为接近指数威布尔分布,其拟合优度均大于0.989 95,而在弱到中等起伏区,Gamma-Gamma分布拟合效果优于对数正态分布.A wireless optical transmission experiment with a link length of 610 m was carried out at night in Lanzhou area to investigate the statistical characteristics of light intensity fluctuation in sunny,overcast,sleet and dust days.The atmospheric structure constant of refractive index Cn^2 in different meteorological conditions were measured by using the scintillation method.The measured maximum,minimum and mean value and the standard deviation of Cn^2 indicate that the range of Cn^2 is 1.06×10^-15 m^-2/3-1.05×10^-13 m^-2/3 of the experimental period,which belongs to moderate turbulence.Moreover,it also indicates that the fluctuation of Cn^2 in sunny day and sleet day are greater than overcast day and dust day.Furthermore,Rytov variance is analyzed by using the measured light intensity values.The results show that in sunny day,sleet day and dust day,the light intensity fluctuation belongs to weak fluctuation at most of the time and there is a small part of the time it belongs to moderate fluctuation.However,the light intensity fluctuation in overcast day belongs to weak fluctuation in all time.The light intensity fluctuation in sunny day and sleep day are greater than overcast day and dust day.We can conclude that the probability distribution of light intensity in different meteorological conditions is closest to the exponential weibull distribution by comparing the nonlinear fitting results of the logarithmic normal,Gamma-Gamma and exponential Weibull distribution.The goodness of exponential Weibull distribution is greater than 0.989 95.In the weak to medium fluctuation region,the Gamma-Gamma distribution fits better than the lognormal distribution.

关 键 词：激光传输 湍流强度 光强起伏 Rytov方差 概率分布 

分 类 号：TN929.1[电子电信—通信与信息系统]