Application solutions of WSN and wireless measurement technology

1. Definition of terms

Wireless Sensor Network (WSN) is a multi-hop self-organizing network system composed of a large number of cheap micro sensor nodes deployed in the monitoring area through wireless communication. Its purpose is to collaboratively sense, collect and process the information of the sensed objects in the network coverage area and send it to the observer. Sensors, sensed objects and observers constitute the three elements of wireless sensor networks. As a wireless self-organizing two-way communication network, the sensor network can automatically complete the networking of various irregularly distributed sensors and control nodes with the greatest flexibility.

As an important branch of wireless measurement technology, WSN technology is increasingly favored and concerned by application engineers. It is widely used not only in industrial control and environmental monitoring, but also in military industry and aerospace. The prospects of wireless measurement technology led by WSN are unlimited. Its application fields have been extended to military, aviation, anti-terrorism, explosion-proof, disaster relief, environment, medical treatment, health care, home, industry, commerce and other fields. Some fields have risen to the height of national strategy.

2. Solution Introduction

A complete wireless measurement network consists of three parts: sensor part (WSN), data processing part, and data application part, as shown in Figure 1.

The sensor part is WSN - wireless sensor, which can be selected and used according to on-site needs; the data application part is actually the software system, which can be classified and designed according to application needs; the core part is the data processing unit, which can choose a single-chip microcomputer or ARM system according to application needs.

The support system of the wireless measurement system is also very important. For the WSN part, it must be powered by batteries, while for the data application part, only a computer with Internet access is needed, and the data processing part can use different power supply systems according to actual needs.

From the above figure, we can see that the biggest advantage of the wireless measurement system is that the three parts have no hard connection with each other. In other words, there is no physical relationship between them except data exchange, which effectively avoids complex interference and resource allocation between each other. I think this is the key to the vigorous development of wireless measurement technology.

3. Key technologies

Undoubtedly, the most critical part of the wireless measurement system is the data processing unit, and the most important part is of course the two wireless communication modules, one is the short-distance communication module and the other is the long-distance communication module. There are many articles and products about the long-distance communication module, which will not be described here. There are also many products, including SIMENS, SIMCOM, WAVECOM, etc. from abroad, and Huawei, ZTE, Youfang, etc. from China. Customers can choose products with good cost performance according to their needs. Here we mainly introduce the short-distance communication module designed by our company---WT3224.

The WT3224 module is designed by Beijing Woyintech Electronic Information Technology Co., Ltd. The main control chip adopts TI's CC1110 solution and SMD structure design. In order to meet the needs of WSN network, the module integrates RF power amplifier circuit inside, and the maximum RF transmission distance can reach 20dB, which can be selected and used according to needs. WT3224 has two working modes, one is independent working mode, in which the module works autonomously to realize the real WSN function; the other is online working mode, which can be used as a standard serial port device of the main control microcontroller, thereby realizing the wireless connection from the main control computer to the WSN.

4. Specific Application

According to the complete scheme of wireless measurement, we have successfully applied the above scheme to two systems, namely, the comprehensive online monitoring system of transmission lines and the online monitoring system of road traffic information.

The comprehensive online monitoring system of transmission lines realizes various status parameters of power system transmission lines in operation, such as various states of transmission conductors, including conductor vibration and conductor temperature. It is definitely not feasible to use traditional wired measurement technology, because it is impossible to lay analog data channels in transmission lines with high voltage, harsh environment and high interference. Therefore, it can be easily realized by using WSN network. You only need to hang completely independent WSN sensors on the transmission lines that need to be measured, and then send the digitized data to the data concentrator, and then send the data to the monitoring center through the remote transmission function. In this way, you can implement line monitoring while sitting in front of the computer in the office.

Another practical application of WSN wireless measurement is the online monitoring system for road traffic information. How to realize the monitoring of road traffic information and monitor the actual traffic status of each road and the relationship between them in a simple and convenient way has always been of great concern to the transportation department, such as road traffic volume, speed, vehicle type status, the relationship between road environment information and traffic volume and speed, etc. The traditional method is often to dig up the road and lay wiring, which is not only very complicated but also destroys the original state of the road. Now the use of WSN network makes the design very simple. You only need to dig a small hole where you need to monitor and place the WSN sensor.

5. Conclusion

The application of WSN and wireless measurement technology is extensive, which is subverting the traditional test system structure. I hope this article will play a role in inspiring others and contribute to the vigorous development of WSN technology in China.