雾对无线光通信系统信噪比的影响

目前,无线激光通信系统以其安全性好、高带宽、高容量、成本低以及无需频率许可等优点得到越来越广泛的应用与研究。但通常激光在雾、雪、雨等恶劣气象环境下传输时,信号却产生严重的衰减甚至会造成通信中断,因而就有必要掌握激光在恶劣气象条件下的传输效应和衰减特性。本文从雾的物理特性出发,对激光在雾媒质中的传播衰减特性进行了基础的理论研究。分别给出了无线光通信系统的数字模型、噪声模型,并对数字信噪比的计算进行了理论推导,给出了不同因素对探测器数字信噪比的影响。最后,以工作波长为810nm的激光为例,利用衰减率与透过率之间的关系,给出了在平流雾及辐射雾中数字信噪比随能见度的变化关系曲线,分析了信噪比随视场角的变化关系。该分析说明,雾的能见度对无线光通信系统接收器信号功率及数字信噪比有较大的影响。

Effects of fog on the digital signal to noise ratio of a wireless communication system

The optical wireless communication system(OWC) has been more and more focused because of its security,wide frequency band,good capability and no need for frequency permission.But when transmitted in the fog weather snow,or rain,its signal may be minished or intermitted.So it is very necessary to hold its characteristic of attenuation and transmission.In this paper,mathematical and noise model for OWC are analyzed,effects of fog on the digital signal to noise ratio of a free space optical wireless communication system are discussed.At last,a numerical results of 810nm laser are given to show these effects which given by fog on the signal to ratio and the signal power.