Design And Implementation Of High Speed Underwater Visible Light Communication System

With the further development of marine resources,the communication between mankind and the oceans is becoming more and more frequent,and the need for high-speed underwater wireless communication technology is urgently needed.At present,underwater acoustic communication is the main way of underwater wireless communication.However,due to the limitation of underwater acoustic bandwidth,the underwater acoustic communication can not achieve the effective increase of transmission rate.In addition,due to the severe attenuation of underwater electromagnetic waves,underwater electromagnetic communication can not achieve high-speed underwater communication.450 ~ 550 nm light band-blue and green light attenuation is smaller than other light band in the water,which laid the foundation for the development of underwater optical communication.In addition,underwater optical communication system has the advantages of large transmission bandwidth,high data transmission efficiency and small size of communication equipment,which can solve the problem of underwater high-speed wireless transmission.However,the underwater channel transmission environment is complex,and the development of underwater optical communication is slow,until the higher coding mode,high power light source and high processing rate chip in recent years had made the underwater optical communication become a hotspot of the research.In this paper,an underwater high-speed optical communication system based on Pulse Position Modulation(PPM)is designed and implemented.The system uses the communication interface to receive the datas which are sent by the host computer software.The slave computer adopts the field Programming gate array(Field-Programmable Gate Array,referred to as FPGA)development platform for PPM modulation and demodulation processing.The paper mainly completes the following work:First of all,the system hardware design: the system complete the transmitter light source drive circuit,optical receiver circuit,external signal processing circuit and other hardware circuit design,including the corresponding device function analysis and selection.And through the signal detection to complete the hardware circuit design feasibility and efficiency testing.Secondly,based on Quartus II11.0 development software using hardware description language software part of the design.Mainly to complete receiving of the data signal,and the data for PPM modulation and demodulation processing coding design.Through the separate design of the functional sub-modules in PPM modulation and demodulation,the data processing function is realized and simulated by waveform simulation software.At the same time,each function sub-module verifies the feasibility of each module design according to the waveform simulation result.Finally,the experimental results of underwater optical communication system designed in this paper are analyzed,and the feasibility of the design is verified further.Experiments show that the design based on PPM modulation of underwater visible high-speed communication system can realize high speed data transmission rate of Mbps in the range of minimum error rate in wireless data communication,finish the communication of underwater channel accurately and efficiently.