Empty - To The Optical Communication System Design And Decomposition Of The Key Technology And Channel Simulation

Because of its wide bandwidth, small scale and high secrecy, space-to-ground optical communications becomes the optimum solution for space to ground information transfer. It has important meaning and promising prospect.This paper is mainly study of characteristics of space-to-ground atmospheric stochastic channel. It is a key part of space-to-ground optical communication systems, and it can be good reference to the design and realization of space-to-ground optical communication systems.Firstly, the characteristics of space-to-ground optical communication systems are introduced. The principle and key technologies of space-to-ground optical communication systems are also analyzed. The same time, we give emphasis to space-to-ground atmospheric stochastic channel. Secondly, we build the physics and mathematical model of space-to-ground optical communication systems. And the link equation is deducted, based on which we calculate the communication link. The design of space-to-ground optical communication systems is also provided, including transmission and receiving terminal, optical subsystem, modulating and detecting scheme. Subsequently, we stress on the absorption and scattering characteristics of space-to-ground atmospheric stochastic channel. Models describing laser beam propagate through horizontal and slant atmospheric stochastic channel are built. And we also make the simulation of space-to-ground optical propagation by using the software of MATLAB, including scintillation, turbulent structure constant of atmosphere and spot of horizontal optical propagation. At last, we get some experiment data by self-made experiment hardware, which is able to display and measure parameters of horizontal optical propagation through atmospheric stochastic channel real-timely.We have the following results through simulation and experiments: i) turbulent structure constant of atmosphere decreases with altitude; ii) turbulence induced power scintillation decreases with the optical wavelength; iii) scintillation of space-to-ground optical propagation is smaller than that of horizontal optical propagation; iv) power scintillation of space-to-ground optical propagation increases with wavelength; Results above are accord with existent theory. What's more, the last result discovers a new rule.