introduction
The vehicle monitoring system based on GPS / GPRS began to be applied in China in the early 1990s, and mature products appeared gradually after 2000. At present, the data transmission methods of many navigation and positioning products are not optimized, and the relatively real-time and stable monitoring tasks cannot be completed with less traffic, which affects the real-time and reliability of the entire system.
This article introduces the design of the GPS monitoring system based on the GPRS network from the perspective of the overall system design. The GPRS network is selected as the main GSM communication method and the auxiliary communication method. This communication method has strong stability and can be smoothly upgraded in the face of future 3G networks. It consumes less traffic, and the GPRS network supports TCP / IP protocol, which makes wireless data transmission easier and expands functions.
GPRS (General Packet Radio Service) is a data service opened on the existing GSM network. Compared with the original GSM dial-up data exchange transmission method, it has "always online", "pay by flow rate", and "quick login" "," Support TCP / IP protocol "," Suitable for small and medium data volume transmission "and other advantages. On the basis of GSM, the GPRS system has added network element equipment such as a packet control unit (PCU), a serving GPRS support node SGSN (serving GPRS support node), and a gateway GPRS support node GGSN (gateway GPRS suppor t node).
1 Overall vehicle monitoring system and communication channel
The vehicle monitoring and management system includes a server, a monitoring service terminal, an in-vehicle terminal, a peripheral web browser manager and a user mobile phone manager. Each part is centered on the server, organized and cooperated through GSM / GPRS network and Internet network to complete functions such as real-time monitoring and management of vehicles. The overall block diagram of the system is shown in Figure 1.
Figure 1 Block diagram of vehicle monitoring system
Vehicle terminal integrated control chip (MCU), GPS positioning module, GPRS data transmission module and voice module and other peripheral equipment. The GPS positioning module collects positioning information and sends it to the MCU through the serial port. After the MCU is analyzed and packaged, it is sent to the GPRS module through the serial port to complete the information collection, analysis and transmission process.
In data transmission, the GPRS network and the Internet network jointly build a system data transmission channel, and maintain three communication channels between the vehicle-mounted machine and the monitoring center:
1) T CP protocol command channel-adopts T CP protocol ASCII encoding transmission.
2) T CP protocol data channel-data is transmitted in binary code, and transmitted in the same SOCKET as the command channel information.
3) UDP protocol data channel-real-time upload data is transmitted using UDP protocol using binary encoding.
The server applies for a static IP address, opens the corresponding TCP and U DP ports, and opens threads to complete data receiving and storage work.
The game keyboard requires a strong sense of key paragraphs,so as to produce a special feel suitable for game entertainment,and achieve a good experience for players in the game. The keyboard is one of the indispensable computer peripherals in our life. The previous keyboard has been used as an input device for office typing.With the emergence of computer games, the keyboard has gradually become a peripherals for games. Due to the relatively low performance of early computers,the way of computer games in this period is also relatively simple,ordinary office and home keyboard can completely meet the needs of players.However, with the continuous upgrading of hardware performance,the fun and complexity of games are also increasing, and the requirements for keyboard performance are also getting higher and higher,so the professional Gaming Keyboard was born.
As one of the most important peripherals for playing games,the tactile feel of the gaming keyboard is the most important reference.Tactile sensation is mainly determined by the strength of the key resistance degree.To judge the feel of a keyboard,it will be tested from whether the key elastic is moderate,whether the key force is uniform,whether the key cap is loose or shaken,and whether the key process is appropriate. Although different players have different requirements for the stretch and range of the keys,the most commonly accepted peripherals for playing games are the Black Axis Gaming Keyboard Mechanical.
The appearance includes the color and shape of the keyboard.A nice and stylish gaming keyboard will add a lot of color to your desktop,while a stuffy Wireless Gaming Keyboard will make you feel dull when playing games. Therefore,for the keyboard,as long as the player feels beautiful like, practical can be.
Gaming Keyboard,Led Gaming Keyboard,Keyboard Gaming Mobile,Optical Mechanical Keyboard
Henan Yijiao Trading Co., Ltd , https://www.yjusbcable.com