The Design Of Underwater LED Visible Light Multimedia Communication System

Since the 21st century,countries around the world have paid more and more attention to the exploitation and utilization of ocean resources and the protection of ocean rights and interests.However,the exploration and higher requirements are put forward for the systematicness,high speed and high efficiency of underwater communication means.At present,the main underwater communication methods include laying submarine optical cable,underwater long-wave communication and underwater acoustic communication.However,there are still some shortcomings such as large,expensive equipment,unfavorable integration,low communication rate,poor directivity and confidentiality.As a new underwater wireless communication technology,the underwater visible light communication technology overcomes the above disadvantages.We will study and analyze the key technologies of underwater communication based on visible light and complish an entire underwater multimedia LED communication system based on FPGA,and.The specific work is as follows:(1)this thesis introduces the main underwater communication modes and their advantages and disadvantages,and expounds the development status of underwater visible light communication technology.(2)the key technologies of the underwater visible light communication system are analyzed,the channel characteristics of visible light in underwater are introduced,the analytical model is given from absorption,scattering and other factors,and the characteristics of optical devices and photodetectors are introduced.(3)introduced the design process of the system hardware,and verified the feasibility of the hardware platform through experiments.In the design of optical transmitter,the selection of transmitter device and the design of driving circuit are mainly introduced.In the design of optical receiver,the selection of optical receiver circuit and the design of signal processing circuit are mainly introduced.(4)performance comparison of light modulation,dimming and coding technologies based on FPGA is analyzed.The OOK,LPPM and DPIM modulation technologies are analyzed.In the dimming technology,the PWM dimming technology is introduced and the OOK based PWM dimming technology is proposed.Manchester code and 4B/6B code are introduced.(5)designed the underwater multimedia transmission system based on SOPC,designed the Ethernet and audio communication module,and tested and analyzed their performance.