Research On The Wireless Audio Communication System Based On Single Photon

Wireless optical communication is also known as free space optical communication.With obvious advantages like high communication speed,less electromagnetic interference,no need for frequency permission and flexible networking,it is developing rapidly in deep space communications,ultraviolet communications,underwater communications,atmospheric lasers and other communication fields.However,the long-distance wireless optical communication has shortcomings of link interruption,high bit error rate,and too many burst errors,due to the flicker of light intensity and the quantum effect of light.Thus,the long-distance wireless optical communication transmission with high reliability has gradually become a research hotspot in recent years.To achieve long-distance high-reliability wireless optical communications,single-photon detectors with single-photon-limited sensitivity are used for detecting optical signals at the receiving end.This paper studies how to extract single photon communication signals,considering the feature that when the single photon detector is used for signal detection,output signals of wireless optical communication receivers are discrete pulse sequences.A single photon wireless audio communication system is built and communication performance tests are simulated in underwater environments.The main accomplishments are as follows.（1）The research status is investigated and the development trend is analyzed,within the field of optical communications and underwater wireless optical communications based on the photon counting technique.And the principles of photon-counting wireless optical communications are expounded.（2）A scheme is proposed for designing the whole single-photon wireless audio communication system.The single-photon wireless audio communication system is built successfully,with a single-photon source for modulation developed,transceiver modules integrated and the underwater environment sink simulated.The system achieves high-quality audio communications.（3）A signal extraction method implemented via FPGA is proposed for single-photon communications,given the characteristics that the output of communication receivers is discrete pulse signals.Single-photon communication signals can be quickly extracted through three steps:single-photon pulse broadening,single-photon signal extraction based on pulse interval,and signal de-tailing processing.（4）An experiment system is built to test the underwater communication performance.The influence of factors,such as light intensity of the single-photon source radiated,settings of baud rat,and extraction circuit parameters on the communication performance is tested and analyzed.The test results show that the bit error rate of our system stays as low as the order 10^-4,when the single photon source voltage is 5 V and the system's baud rate 100kbps.Finally,a physical model of the system for data transmission is established to calculate the theoretical communication distance of the single-photon wireless communication system.The calculation shows that the theoretical maximum communication distance of this system can reach about500 meters in type I ocean water when the system parameters are set to the best performance parameters.