Measurement And Research On The Influence Of Atmospheric Turbulence On Laser Communication Systems

Wireless optical communication is a method of using optical signals to achieve long-distance data transmission,which has the characteristics of high bandwidth and strong anti-interference.When the signal beam of a wireless optical communication system is transmitted in atmospheric media,random changes in local temperature,pressure,and other parameters in the atmosphere can generate atmospheric turbulence noise,causing random fluctuations in the amplitude and phase of the signal light,causing beam distortion,spot flicker,and other phenomena,seriously affecting the communication quality of the system.The form of atmospheric turbulence noise is related to the physical characteristics of specific atmospheric turbulence,and it will have different impacts on wireless optical communication systems as the actual atmospheric turbulence constantly changes.Especially in longdistance and complex terrain situations,the impact of atmospheric turbulence noise is more prominent,which greatly limits the practical application of wireless optical communication.This article mainly studies the impact of atmospheric turbulence noise on communication systems in wireless optical communication and the suppression effect of aperture smoothing technology on turbulence effects.The main work is as follows:1.Introduced the basic principles of atmospheric turbulence motion;Detailed analysis was conducted on the applicability of various atmospheric turbulence power spectrum models and atmospheric turbulence noise channel models;A simulation analysis was conducted on the impact of atmospheric turbulence noise on the performance of wireless optical communication systems.2.Simulation analysis was conducted on the suppression effect of aperture smoothing technology on turbulence effects,and three measured links were built to measure the scintillation index,skewness and steepness,atmospheric refractive index structure constant,and fading characteristics under different receiving apertures.3.Three measured links were set up,and the probability density distribution,refractive index structure constant,slope and steepness,fading characteristics and outage probability of the actual atmospheric turbulence noise samples were analyzed.The results show that the structure constant of atmospheric refractive index and Rytov variance increase with the increase of transmission distance.The turbulence intensity measured by the 0.42km and 1.32km links is in the weak and weak middle turbulence regions,respectively.The probability density distribution follows the logarithmic normal distribution.At the same time,the fluctuation degree of light intensity decreases in order of dust days,sunny days,haze days,snow days,light rain,moderate rain,heavy rain and cloudy days;The turbulence intensity measured by 10.3 km link is in the middle strong turbulence area,and the probability density distribution follows the double gamma distribution;The probability of decline and probability of interruption increase in the order of cloudy,heavy,moderate,light,snowy,hazy,sunny,and dusty days;In the experimental study of aperture smoothing effect,the scintillation index,atmospheric refractive index structure constant,and fading probability all increase in the order of D_G=l0mm,D_G=20mm,D_G=50mm,and D_G=105mm.