Research On Monitoring Of Environmental Parameters In Coal Mines Based On Visible Light Communication

The safety of underground coal mines has always been the focus of people's attention.However,the existing underground coal mine environmental monitoring systems rely on traditional communication methods,which are vulnerable to electromagnetic interference and have weak confidentiality.In recent years,the rapid development of visible light communication technology uses high-frequency flashing of lighting LEDs for information transmission.It is not susceptible to electromagnetic interference and has strong confidentiality.It can enable LEDs in coal mines to achieve lighting while having communication functions.In view of this,this article mainly studies the application of visible light communication in the underground coal mine environment monitoring system.Aiming at the complex communication environment in coal mines,this paper proposes to apply visible light communication to the coal mine environment monitoring system to expand the means of coal mine environment monitoring,and completes the design of the coal mine environment monitoring system based on visible light communication.First,on the basis of introducing the principle of visible light communication,the overall framework and implementation scheme of the underground coal mine visible light communication system are studied and explored.The design of the hardware circuit is emphasized,including the sensor detection circuit and the LED drive circuit at the transmitter,the photoelectric recriving circuit at the receiver.In order to achieve the coal mine environment monitoring index,the type of sensors is strictly screened and the corresponding detection circuit design principle of each sensor is described in detail.In this paper,an LED driver circuit with a carrier removal circuit is designed to reduce the influence of the carriers on the junction capacitance on the modulation rate of the LED when the LED is extinguished.Aiming at the problem that the light attenuation caused by the communication environment in coal mines leads to the weak light intensity of the light signal detected at the receiver,an avalanche diode is selected and a receiving circuit with the function of detecting weak light signals is designed.Afterwards,the PPM modulation is improved by adding synchronous header pulse,which improves the bandwidth utilization of the PPM modulation while reducing the strictness of the clock synchronization during the demodulation.FPGA is used to complete the software design of the whole system,including the design of the interface module,modulation and demodulation module,CRC module,CRC calibration module and serial port module in the uplink and downlink,and the function simulation of each module is carried out.The simulation results show that the designed modules are functioning normally.Finally,the hardware circuit test and data communication test are performed on the entire system.The test results show that the hardware circuit functions normally.The carrier removal circuit can effectively reduce the influence of the carriers on the junction capacitance on the modulation rate of the LED when the LED is turned off.Under the condition of no distortion of the waveform at the receiving end,the LED modulation rate can be increased to 3M,the system software runs normally,the entire system can realize the environmental monitoring function,the communication distance can reach 75cm,and the data transmission rate can reach 3Mbps.Figure[79]table[9]reference[71]...