Pick   To: Introduce a method for implementing a centralized control system for civil air defense and disaster warning based on GPRS . The system uses GPRS wireless data communication technology to realize remote centralized broadcast and monitoring of civil air defense and disaster alarms, featuring fast control response and low construction and maintenance costs. GPRS (General Packet Radio Service - General Packet Radio Service), which uses the concept of "packet switching" the development of a wireless transmission. GPRS is a new type of packet data transmission service opened on the existing GSM network. With GPRS wireless access technology, people can easily access the Internet whenever and wherever. The use of GPRS wireless access technology to form a wireless data transmission system has a large application range. At present, almost all medium and low-rate data transmission services can be applied, including: industrial remote signaling, telemetry, remote control, and POS networking in the financial and retail industries. , automatic cabinet machine networking, mobile banking, etc., as well as vehicle mobility data transmission, mobile vehicle scheduling and monitoring. Application of GPRS technology in the mobile phone has been very extensive, and in industrial remote, telemetry, remote control aspect has just started, this is the use of GPRS wireless access technology to design and implement a civil defense and disaster warning centralized control system, is the GPRS technology Typical applications for industrial telecom, telemetry, and remote control. system structure The system is mainly composed of two parts: the central control center and the alarm remote control terminal. The other parts are provided by China Mobile Communications Corporation. The structure is shown in Figure 1 . The alarm issuance command is issued by the computer of the central control center (the central control center can be mobile or fixed ) , and the alarm command issued by the central control center is transmitted to the alarm remote control terminal via the Internet network and the GSM/GPRS network. After the terminal receives the command, the alarm ( electric alarm, electro-acoustic alarm ) is activated, and the alarm sound is automatically transmitted back to the central control center and displayed on the electronic map of the computer. Figure 1  System block diagram Figure 2  GPRS data communication module structure block diagram Figure 3  Alarm remote control terminal block diagram GPRS wireless data communication In the implementation process of this system, the realization of GPRS wireless data communication is a very critical issue. GPRS is a new bearer service developed on the existing GSM system. The purpose is to provide GSM users with data services in packet form. GPRS uses the same wireless modulation standard as GSM , the same frequency band, the same burst structure, the same frequency hopping rules, and the same TDMA frame structure. This new packet data channel is very similar to the current circuit-switched voice traffic channel. . Therefore, the existing Base Station Subsystem (BSS) provides full GPRS coverage from the beginning . GPRS allows users to send and receive data in end-to-end packet transfer mode without the need to utilize network resources in circuit switched mode. Thereby providing an efficient, low-cost wireless packet data service. It is especially suitable for intermittent, bursty and frequent, small amounts of data transmission, as well as for occasional large data transfers. The use of GPRS technology to achieve data packet transmission and reception, the user is always online and according to the flow rate, greatly reducing the operating costs of the system. The theoretical bandwidth of GPRS wireless data transmission can reach 171.2Kbps , the actual application bandwidth is about 40~100Kbps , and TCP/IP connection is provided on its channel ( connecting GPRS/GSM network and Internet network through GGSN ) , which can be used for INTERNET connection. , data transfer and other applications. Then, to achieve GPRS data communication between the central control center and the alarm remote terminal , it is only necessary to follow the TCP/IP protocol and work on the same network level. In the realization process of the system, we designed a GPRS data communication module for the remote control terminal of the alarm , embedded TCP/IP protocol stack to parse the TCP/IP data to realize the transparent transmission of data, and then build the alarm system based on it. Communication protocol. Considering that the GPRS data communication module uses a single-chip microcomputer to implement TCP/IP protocol parsing, a UDP protocol with a small system overhead is used instead of the TCP protocol at the TCP network layer . The GPRS data communication module is mainly composed of CPU , GPRS transceiver module, SIM card holder, configuration / diagnosis module, TTL serial communication interface, extended data memory, etc. The block diagram of the structure is shown in Figure 2 . The GPRS transceiver module uses the MC35 GPRS wireless communication module of SIEMENS . In the MC35 module, PAP (Password AuthenTIcaTIon Protocol) and CHAP (Challenge Handshake AuthenTIcaTIon Protocol) are embedded in the PPP (Point-to-Point Protocol) connection to the GPRS data exchange center. When the call connection is established, the MC35 is connected. It can send and receive GPRS packet data according to the GPRS network protocol and parse it, and output IP datagram. The MC35 provides a standard AT command interface and an RS-232 interface for connection to external application systems. In addition, a SIM card interface is provided for connecting the SIM card holders to connect to different GPRS operating networks. The CPU uses Winbond 's 77E58 microcontroller chip, which has 32K of program memory inside , which is enough to embed IP and UDP protocol stack programs. At the same time, the 77E58 has two serial ports, one for connecting to the GPRS transceiver module and the other for outputting data after UDP parsing. Alarm remote terminal The alarm remote control terminal is an alarm actuator. It can be either an electric alarm control terminal or an electro-acoustic alarm control terminal. The working principle is: when the alarm controller receives a legal command ( remote control ) or receives a valid keyboard operation ( manual operation, password protection ) , the controller controls the electric or electro-acoustic alarm drive circuit to complete the electric or electric The alarm of the audible alarm. Its structural block diagram is shown in Figure 3 . In the alarm remote control terminal, it is composed of Atmel 's AT89C52 single-chip microcomputer, GPRS communication module, voice circuit, sound intensity detection module, man-machine interface, alarm driver and other functional modules to complete communication, playback, status detection, manual operation and other functions. Conclusion The application of GPRS wireless access technology in industrial remote signaling, telemetry and remote control will have broad prospects. Using GPRS wireless access technologies to achieve centralized control of air defense and disaster alerts, is only one aspect of technology GPRS. The alarm remote control system has been applied in many cities. M12 Circular Waterproof Connector 12 A Code,M12 B Code,M12 C Code,M12 L Code,M12 S Code,M12 X Code,M12 P Code,M12 T Code,M12 D Code,M12 K Code,Circular Waterproof Connectors Shenzhen HuaTao Electronic Co., LTD , https://www.htconnector.com
