Multi-parameter On-line Monitoring System Of Air Quality

Clean air on earth is the necessary conditions for human survival,and the air can be self-purified by natural settlement,precipitation,ultraviolet radiation in the sunlight,etc.Now with the rapid development of the global economy and the emissions of industrial waste gas and vehicle exhaust,urban air pollution has become increasingly serious.Air quality monitoring not only can help people get to know the status of air quality and to make preventive measures in time,but also can provide urban residents air quality data of the surrounding area.In view of the problem that the current data provided by State Environmental Protection Department official website and other major air quality query platforms is not detailed and the location of the data is not accurate enough,the paper designed a multi-parameter on-line monitoring system of air quality to make up for these shortages and achieved a fine monitoring.The system used multi-point distribution of multiple sensors to collect data,and the wireless sensor network and LoRa communication technology and GPRS communication technology were combined to solve the issues of multi-parameter data acquisition,wireless data transmission.The main work of the paper is as follows:Firstly,the multi-parameter on-line monitoring system was designed.The sensor nodes in different areas of the city collected many kinds of air quality parameters,including temperature and humidity,CO2,CO,SO2,NO2,PM2.5,a plurality of sensor nodes and a gateway node formed a star wireless sensor network.Different nodes communicated with each other via LoRa communication technology,and the gateway node transmitted the data of each sensor node to the server via the GPRS module,the residents can query the monitoring data through the client,mobile terminal,Web and other ways.Secondly,the hardware and software parts of the system were designed and implemented.The hardware circuit part included related circuit of the optical gas sensor and PM2.5 sensor to detect the air parameter;the sensor node master MSP430 and its peripheral circuit,the Lo Ra communication module SX1276 and its receive and transmit circuit;the gateway node master STM32 and its peripheral circuit and the serial circuit connected to the GPRS module SIM900 A.The software part included the data acquisition of the sensor nodes,the communication between the gateway node and the sensor node,the data transmission and alarm of the gateway node,and the design of the software of the host computer.Finally,the multi-parameter on-line monitoring system was implemented and tested.According to the design requirements,a test system was built in the school,the data collected by the system was analyzed,the optical fiber gas sensor was calibrated,and the network communication was tested to ensure the maximum degree of the communication of the quality and distance.The test results show that the system can run stably for a long time,and it can realize multi-parameter acquisition and long-distance transmission.It can be used in the monitoring of urban air quality,the monitoring of the factor producing flammable and explosive gases,etc.