Application Of LoRa Communication Technology In Permafrost Monitoring System

Global warming and increased human activities have led to the degradation of permafrost in the northern part of Greater Khingan Range and affected to the local ecological environment.Although scientists can analyze the relationship between permafrost and the environment through the pennafrost temperature monitoring system in the northern part of Greater Khingan Range,they can hardly reach the data from that system without mobile network signal there.Given the permafrost temperature monitoring system in Greater Khingan Range,this thesis studies the communication problem of the data from monitoring stations without mobile network signal.First,LoRa low-power long-distance communication technology is used to realize the extension of the mobile public network under the condition of field power supply.Besides,a mobile public network communication gateway based on LoRa communication technology and a LoRa communication device based on STM32L476 are designed so that the data from monitoring stations can be collected and communicated without mobile public network signal.The specific work is as follows:First,LoRa technology is adopted to extend the mobile public network,and sub-centers or gateways are set up in the place where there is mobile public network signal.As a result,the communication between sub-centers without mobile public network signal and the monitoring sub-station is realized.This study introduces LoRa communication technology,as well as the mechanism and process of collecting data from multi-station.LoRa module cannot automatically shut down and data acquisition device is frequently woken up in the current short-range wireless communication,resulting in excessive power consumption of the system.In order to solve these problems,this paper designs a LoRa communication device of which a low-power ARM platform-STM32L476 is the MCU.The device controls the LoRa module and the communication process between the LoRa module and its monitoring station,and through monitoring the voltage of the solar power supply system,the control system can control the powering of the LoRa module to reduce power consumption of the system when the charge amount is enough.The hardware and software design of the device is provided,including the hardware and software design of address storage of monitoring station(substation)using I2C interface ferroelectric memory.Second,in order to reduce the correlation between the power supply of the data acquisition instrument of the monitoring station and that of the communication device,the combination of solar panels and Super-Capacitors is adopted to provide independent power supply for the LoRa communication device.Based on the power consumption estimation of LoRa communication device,the power of the solar panel and the capacity of the Super-Capacitor are set up.In order to further reduce the power consumption of voltage measurement,the Ultra-micro power RC integral method is adopted in this thesis to realize the voltage measurement scheme with static consumption close to 0.Besides,the circuit design and program design are given.The pulse period is tested and calibrated by GPS IPPS,which makes the measurement error less than 0.2V and meets the accuracy requirement for the application of the system.Finally,this paper introduces the long-distance communication experiment report and the experiment report of collecting data and communication of multi-substation.Experimental data shows that the packet loss rate is less than 10%when the communication distance is 6 kilometers,which can meet the communication needs of Greater Khingan Range whose monitoring substation without mobile public network signal is at a distance of 4 kilometers with another.