Wireless environmental protection detection system solution based on ZigBee technology
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1. System background
Today, when the human living environment is deteriorating, it is very necessary to establish a complete environmental monitoring system. my country continues to place environmental protection in a prominent strategic position. Committed to water pollution prevention and control projects in key river basins and urban sewage and garbage treatment. Environmental protection instruments are mainly used in environmental quality monitoring and pollution source monitoring. Environmental protection is mainly to solve the two strategic and overall environmental ecological pollution problems of my country’s water environment and atmospheric environment.
1.1. The main requirements of environmental protection instruments are as follows:
(1) Environmental quality monitoring: At present, more than 4,000 monitoring stations have been established in the national environmental protection system and various departments, industries, and enterprises. The National Environmental Protection Agency plans to equip more than 400 national network monitoring stations across the country; more than 350 environmental information centers; 100 Automatic monitoring system for urban air and ground.
(2) Pollution source monitoring: The state will implement total discharge control and reduction of major pollutants for 18,000 key polluting enterprises across the country to improve environmental quality. Therefore, 18,000 major polluters are required to gradually install online continuous automatic monitoring systems.
(3) Remote sensing and remote sensing instruments: including monitoring of deserts, grasslands, forests, oceans, and agricultural ecological environments, as well as remote sensing and remote sensing of air pollution, water pollution (such as ocean red tides, oil spill pollution), and pollution sources.
1.2. Current status of the industry
At present, most of the environmental monitoring instruments and meters produced in my country are middle and low-end products, with single functions, high failure rates, and low added value, and they are far from being able to meet actual needs in terms of variety and quantity.
Relevant experts believe that the development trend of environmental monitoring instruments in my country has the following points: 1. Development towards three modernizations, namely automation, intelligence and networking; 2. Development from labor-intensive to technology-intensive; 3. From narrower fields Monitoring is developing in the direction of monitoring in all-round areas; 4. Development from pure ground environmental monitoring to a combination of remote sensing environmental monitoring.
Dealing with the data transmission problem of environmental detection points distributed in various places has always been a difficult point in establishing an environmental monitoring system. If the data of environmental detection points distributed in various places is not managed online in real time, it will bring a lot of problems to the management department. problem. Unable to implement real-time management and 24-hour monitoring and supervision. This system uses ZIGBEE wireless technology to realize real-time management and 24-hour monitoring and supervision on the basis of existing equipment. As my country pays more and more attention to environmental monitoring, on the basis of the original single-point environmental monitoring, environmental monitoring stations in various places have established some unattended inspection points to monitor the environmental quality in a wider and more real-time manner. There are better ways to upload and share information about measurement equipment in different places. Here we use a wireless technology given to ZIGBEE technology to solve such applications.
2. Introduction to System Technology
2.1 Introduction to Zigbee Technology
Zigbee is a commercial name for a wireless connection technology, which mainly solves the application of low-cost, low-power, low-complexity, low transmission rate, and short-distance device networking. Internationally, the IEEE802.15.4 working group and the Zigbee Alliance are jointly committed to the promotion of this wireless connection technology. Among them, the IEEE802.15.4 working group is mainly responsible for formulating the zigbee physical layer and MAC layer protocols, and the remaining protocols mainly refer to and adopt existing standards. , In order to facilitate the interconnection and intercommunication of equipment from different manufacturers in the future; the zigbee alliance is responsible for high-level applications and marketing. The zigbee alliance, established in 2002, has now attracted hundreds of chip companies and wireless device companies to join. At present, international giants such as Freescale and TI have launched relatively mature zigbee development platforms.
The ZigBee standard is based on the 802.15.4 protocol stack and has powerful device networking capabilities. It supports three main types of self-organizing wireless networks, namely star structure, mesh structure and cluster tree. , Especially the mesh structure, has strong network robustness and system reliability. If there is no direct path, communication can also be done by means of “multi-hop”; this topology can also form an extremely complex network; in addition, the network also has self-organization and self-healing functions.
2.2.
Figure 1 ZIGBEE star network structure
Figure 2 ZIGBEE mesh network structure
Three, the system plan
Through the previous analysis of the technical requirements of the environmental protection detection system, combined with the technical characteristics and technical advantages of zigbee, it is a very ideal solution to use zigbee technology to realize a wireless environmental protection detection system:
3.1. System composition:
A complete environmental monitoring system is composed of various environmental monitoring sensor equipment and communication networks:
①Environmental monitoring sensors include:
1) Particulate matter monitoring subsystem: dust detector
2) Flue gas parameter measurement subsystem: flow measuring instrument; temperature measuring instrument; pressure measuring instrument
3) Sampling and pretreatment system: measurement with heat treatment; measurement of condensation and water removal; measurement of filtration
4) Gaseous pollutant monitoring subsystem: SO2 analyzer; NOX analyzer; oxygen analyzer
②Communication network:
As shown in the figure: the sensor is connected to the ZIGBEE module through the RS232 or RS485 interface. By ZIGBEE
The module is connected to the central processing and data transmission system. It completes the wireless upload of sensor data and the wireless issuance of instructions from the upper controller. At the same time, the central processing and data transmission system can use ZIGBEE network or GPRS network to realize wireless upload of local node data (including enterprise environmental monitoring system and environmental protection bureau environmental monitoring system).
Four, system characteristics
1) Establish a comprehensive monitoring system to collect the monitoring information of each node of the network at regular intervals to accurately grasp the environmental pollution situation in time.
2) Full wireless system, convenient for wiring and installation and debugging.
3) The system adopts a modular structure, which can be easily expanded, and has a remote diagnosis function, which is convenient for installation and maintenance. Send the data from the remote collection point to monitoring centers at all levels in real time and reliably. And receive control instructions from monitoring centers at all levels.
With the continuous development of wireless communication technology, in recent years there has been a technology for the wireless networking requirements of low-cost devices, called zigbee, which is a short-distance, low-complexity, low-power, low-data-rate, and low-cost technology. Two-way wireless communication technology is mainly suitable for automatic control, remote control and household equipment networking. We use the combination of zigbee technology and GPRS/CDMA technology to provide a good solution for remote data transmission and communication of environmental monitoring systems. In practical applications, we have chosen to combine zigbee technology with GPRS/CDMA to flexibly construct a wireless meter reading network according to the different distribution of detection points.
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