| Underwater laser communication technology becomes the hotspot of underwater communication research these days.Mastering the key technology of underwater laser communication can help dominate the underwater battlefield,and recently the complexity and variability of seawater channel is one of the main difficulties in underwater laser communication.Under this background,studying the influence of the seawater channel characteristics on optical communication has high practical value in military.In order to further study the characteristics of underwater laser transmission in different channel environments.Its application in weapon detection system and communication system,verify the effects of diameter,density and transmission distance of underwater scatterer on the received photon weight,single photon scattering times and the extent of time broadening,and validate the feasibility of Monte Carlo simulation in the above research,the characteristics of underwater channel have been simulated and tested in this paper.Firstly,the scattering method of light underwater and the research method of underwater channel characteristics are introduced,and the scattering model mainly based on Mie scattering and Monte Carlo simulation method are established.By combining the Mie scattering analysis model with the Monte Carlo simulation method and changing the diameter,density and transmission distance of scatterer in the Mie scattering model,the scattering coefficient,extinction coefficient,asymmetry factor,photon free motion distance and other parameters which need to be set in the simulation process are changed,and the simulation results show that the photon weight decreases with the increase of the diameter,density and transmission distance of the scatterer,the causes of the results are also analyzed;the effect of underwater scatterer diameter on average scattering times of single photon is simulated and the simulation results show that the single photon scattering times increase with the increase of the diameter of the scatterer in the Mie scattering model,and the influence of the diameter of the scatterer on the time broadening is analyzed based on the simulation result.Combined with the experimental requirements and simulation results,the underwater laser transmission experiment and signal receiving system for laser fuze are designed in this paper.First of all,feasible communication modes for underwater fuze are analyzed according to the characteristics of reliability,signal-to-noise ratio and bit error rate of the system,where the suitable communication modes are encoding system of binary duty ratio coding + cyclic redundancy check code and encoding system of sine counting.Then based on the experimental equipment and conditions,the receiving system of sine counting code is designed and applied to the underwater laser transmission experiment,checking whether the influence of different receiving distance,diameter and density of the scatterer and other factors on the sined laser transmission is consistent with Monte Carlo simulation results;the signal data collected from the receiving system are analyzed and compared,showing that the influences of different underwater channel environments on laser transmission are basically the same as the simulation results.Finally,the signal-to-noise ratio of the signal receiving system is analyzed and the method to improve the signal-to-noise ratio is proposed.This paper has not only verified the feasibility of the Monte Carlo simulation method in the research of underwater channel characteristics,but also laid the foundation for the follow-up study of underwater laser communication technology. |
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