Modularization Design Of The Mobile Positioning Terminal And Implementation On The Interface Of Transmission Module

The development of wireless data transmission technology greatly stimulates the development of relative industries. One of the most beneficial fields is the system of data acquisition and transmission. The wireless data transmission technology expands the application of the system. The building and maintaining cost is reduced, designing and running efficiency is raised. The vehicle positioning system (VPS) discussed in this paper is one of the applications.The vehicle positioning system, as a key sub-system, is the terminal application in the Intelligent Transportation System (ITS). The wireless transmission module in VPS serves as the communication link between terminals and service center of ITS. So the stability, security and cost are largely influenced by the wireless transmission module. The mobile communication technology offers an ideal environment for the construction of this module. Among the data transmission services in the mobile communication system, SMS (Short Message Service) and GPRS (General Packet Radio Service) has their own advantages and disadvantages. The two services suit different applications. The research and design based on SMS is simple and can be used in applications without high requirement on data transmission. GPRS is better in security, transmission rate and functionality so is adaptive to more extensive applications.The MC35i wireless module by SIMENS is introduced in the design of wireless data transmission module in the vehicle positioning system. The MC35i is the new generation dual modes GSM/GPRS engine, which enables data transmission over both SMS and GPRS. According to the current requirement by the project, the SMS mode is adopted. The experiment shows that under the control of AT89S52 MCU, the module can implement the sending and receiving of short messages with stability. The specific hardware design offers great possibilities for system upgrades. With slightly modification, the GPRS transmission can be achieved so that the function of the whole system can be extended.