In the 21st century, the status of information has become increasingly important, and the ability to acquire and process information has become a key issue in modern information processing. In the process of informationization of human society, the main means of achieving information exchange through various means of communication. Various needs have led to the rapid development of mobile communications (paging, GSM/GPRS, CDMA) and the Internet. When informationization reaches a certain level, an urgent problem is: how to integrate many scattered production units and information units into the unified informationization process, such as oil well control in large oil fields, mine control in large coal mines, and control of hydrological monitoring points. Wait.
Traditional wireless monitoring systems use radio stations. However, the radio has poor anti-interference and poor confidentiality and is not suitable for use in cities. Wireless monitoring systems that utilize wireless mobile networks are bound to have unparalleled advantages. At present, there are three main methods for mobile wireless transmission of data: GSM short message, GPRS and CDMA.
The GSM network uses short messages to transmit data. Since the short message transmission uses a signaling channel and uses a store-and-forward method, the disadvantages are low data transmission rate, delay, and time uncertainty. GPRS adopts packet switching technology, which can efficiently transmit data and signaling according to the flow rate. The theoretical transmission rate of GPRS can reach 171.2 kb/s, and the actual transmission rate is about 40 kb/s. The CDMA 1X network provides data services in packet form. The CDMA 1X theoretical transmission rate can reach 300 kb/s. The current actual transmission rate is about 100 kb/s, which can be used for applications such as Internet connection and data transmission. CDMA 1X wireless data network has become an important resource in the above-mentioned business informationization because of its wide coverage, low cost, perfect technology, high security and reliability.
This article will introduce the system components of the remote monitoring system and the remote terminals based on the MG815+ wireless module and the ARM LPC2210 microcontroller.
The focus is on the design and implementation of remote terminal hardware and software.
1 system compositionThe system uses the CDMA 1X mobile communication network to complete the wireless transmission of data, eliminating the initial construction cost of the on-site networking and future network maintenance costs. Through the remote terminal, the collected field data is sent to the monitoring center in the form of an IP packet, and the data processing and storage are performed in the monitoring center, and corresponding query, statistics and reporting functions are provided. The monitoring center can also obtain real-time data of the remote terminal by sending an IP packet to the remote terminal, setting monitoring terminal configuration information or control commands.
The outstanding feature of this system is “according to the flow rateâ€. The CDMA 1X network supports the user's “always on†working mode, and adopts the sleep state during the idle time of the terminal. If the data needs to be transmitted, the terminal wakes up and starts working, which greatly saves the money. Cost; in addition, since CDMA uses a pseudo-random sequence PN for spread spectrum/de-spread spread spectrum communication technology, it has natural confidentiality, and the probability that its information is intercepted on the air channel is almost zero, which can ensure the security of data transmission. In addition, due to the comprehensive coverage of the mobile communication network, the networking of the system is very flexible and can meet complex and variable conditions.
The system consists of remote terminal equipment, CDMA network and monitoring center. The block diagram is shown in Figure 1.
Figure 1 System principle
Ningbo Autrends International Trade Co.,Ltd. , https://www.supervapebar.com