Research On Demodulation System Of Optical Fiber Sensing Signal In Coal Mine Underground Communication

Coal resources are one of my country's important energy and mineral resources,and the safe production of coal mines supports the sustainable development of the national economy.When major disasters such as gas explosion and roof fall in coal mines will cause underground power failures and interruption of communication network links,the rescue center will not be able to detect the information of coal mine personnel and increase the difficulty of emergency rescue after disasters.In this paper,combining the characteristics of optical fiber sensing technology that can achieve signal passive detection,based on acoustic detection,research and design an emergency communication optical fiber sensing signal demodulation system based on existing optical cables in coal mines,which can detect the power supply interruption in the mine after a disaster.Voice messages of trapped persons.The research content of this paper mainly includes the following aspects:(1)Analyze the optical fiber sensing signal detection mechanism,explain the principle of acoustic wave information demodulation,and build an optical fiber sound sensing detection system based on the existing optical cable underground in coal mines.The system uses ASE broadband light source as the detection light and optical fiber as the sound sensing medium.With the signal transmission channel,it can listen to the sound signals such as taps and shouts sent by the trapped persons in the tunnel after the power supply is interrupted in the mine,and transmit the signals to the ground,and remote signal demodulation on the ground.(2)Designed an optical fiber sound sensor hardware demodulation system including a signal demodulation system and a data transmission system.Through the design of hardware circuits such as photoelectric conversion,I/V conversion,differential transmission,preamplification,active filtering,impedance matching,power amplification,electro-acoustic conversion,etc.,a signal hardware demodulation system is built to complete the demodulation of sound signals.Reproduction and extraction and restoration;with STM32F407 as the control chip,a data acquisition unit,data control unit,and data transmission unit are designed,and a data transmission system is constructed to transmit the demodulated and restored sound information data to the host computer monitoring system.(3)Developed the optical fiber sound sensing host computer monitoring system based on the MFC application architecture,realized the detection of the sound wave signal under the power supply interruption after the mine disaster,constructed the human-computer interaction interface,and realized the real-time detection of sound information,waveform display,and data Functions such as storage and sound reproduction;a multi-threaded structure is designed to optimize the running speed of the software.The upper computer monitoring system is a data processing and analysis platform,and a network data transmission system has been developed to push the comprehensively processed data analysis results to the staff,so as to realize the multi-party linkage of sound,image,and waveform to detect the actual environment of the mine after the disaster.(4)The optical fiber sensor signal demodulation system experiment platform was built.The optical fiber sound sensor detection system can detect the sound of the laid optical cable and realize the passive collection and transmission of the sound signal;the signal demodulation system can realize the sound signal Demodulation and reproduction;the data transmission system can stably transmit the demodulated and restored sound data to the host computer monitoring system.The upper computer monitoring system can reflect the changes of the external environment in real time through the waveform,and push the disaster occurrence information in time.The experimental results show that: within a test distance of 10 km,the constructed emergency communication optical fiber sensing signal demodulation system can detect sound signals with a frequency of 300Hz-3.4k Hz from 0-10 m away from the optical fiber probe,and the frequency accuracy can reach ±1Hz.The above research shows that the emergency communication optical fiber sensing signal demodulation system uses optical fiber sensing technology to realize the passive detection,acquisition and transmission of sound waves of trapped persons under the power supply state of the mine after a disaster,and solves the problem of communication failure due to power failure.It provides new ideas and technical means for the research on emergency communication and emergency rescue in underground coal mines.