| This paper researched the performance of 3 . 4km line-of-sight laser link under different weather conditions. Effects of haze, fog, rain and atmosphere turbulence on the BER of experimental link are given and theoretical analysis is taken through two communication channel modelsæ¢ttenuation channel and turbulence channel. In chapter l,we give a summary of laser communication and the development of atmosphere laser communication. In chapter 2,we introduce roughly effects of atmosphere on the propagationof laser beams and the laser communication system. They are the general bases of my concrete work (chapter4 to chapter 6).Chapter 3 introduces the experimental link and its instruments. The overall experimental results and the BER of communication system under different weather conditions are given.Chapter 4 gives the effects of haze, fog and rain on the BER of optical communication link and calculates their extinction coefficient. The major reasons of cause to the experimental link's BER are discussed.In chapter 5, experimental results of intensity fluctuation in fine day are given and expected variations in the scintillation over the course of a day are observed. In there, we calculate the turbulent intensity through weak turbulent theory, report the overall BER of link in the presence of strong scintillation, and analyze why cause to the BER. Besides, the characters of BER are comparied with the results of chapter 4.Chapter 6 obtains the BER as function of extinction coefficient by attenuation channel model, which fit for experimental link when thick haze and fog presented. And then we calculate the detection probability of communication system under different turbulent intensity and analyze the relation to BER. In the end, we compare the overall experimental results between Guilin and Beijing.
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