| Because of its wide bandwidth, small scale and high secrecy, free space laser communication becomes the optimum solution for space information transfer. It has important meaning and promising prospectThis paper is mainly study of characteristics of space atmospheric random channel, especially the effect of the random channel to laser communication. It is a key part of space laser communication system, and it can be good reference to the design and realization of free space laser communication system.My work include: firstly, the character of turbulence channel is introduced, the model of the channel was build, and the facula simulation was done by computer, the facula were compared with the photo. Secondly, the characteristics of hydrometeors were done. Based on the relation of the specific rain attenuation and rain rate, the effect of rain to laser communication was analyzed. The drop size distributions for advection and radiation fog were obtained with empirical relations of the liquid water content and the visibility, the characteristics of drop size distribution for different kinds of fog were analyzed and discussed. The fog attenuations at infrared wavelength were computed and analyzed with the fog drop size distribution model of radiation and advection fog, the empirical relation of attenuation with water content or visibility are obtained. Finally, the rate of laser penetrating in atmosphere was calculated.The results through simulation and calculation have been obtained: i) turbulent structure constant of atmosphere decreases with altitude; ii) the more turbulent, the more change of facula;iii) the small rain will not affect laser communication, and the rainstorm will affect laser communication , maybe the communication will cut down;iv) at the same visibility, the attenuation of advection fog is bigger than the attenuation of distribution model of fog.This paper provided the theory to optimize laser communication. |
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