| BeiDou navigation satellite system is our self-developed satellite system. At present, it has successfully covered the Asia-Pacific region, it will achieve global coverage in 2020, with the gradual improvement of the BeiDou navigation satellite system, research and development of a new generation of vehicle terminal system is very important. The civil market proportion of BeiDou navigation terminal products is not high currently, mainly used for defense and other military fields, most domestic and foreign navigation products are relying on GPS technology. Therefore, the development of our own national navigation terminal products is imperative, it will no longer restricted by GPS service both in the military field and civilian field. Civil air-defense is an important part of the national defense forces. National civil air-defense navigation satellite system is an important task of the construction of national civil air-defense information system. BeiDou navigation satellite system incorporate positioning、short message communication and timing as a whole, especially suitable for civil air-defense to carry out emergency command、trend monitor、data transmission and other applications. BeiDou navigation satellite system and related equipment resource is suitable and only option to construct national civil air-defense navigation satellite system. This thesis based on the relevant civil air-defense project background of Anhui Sun Create Electronics Company, combined with satellite navigation technology、embedded technology、computer technology and mobile communication technology, to study and design about BeiDou vehicle terminal system which based on civil air-defense application, to achieve the real-time positioning、short message communication and other functions.Firstly, this thesis combines the relevant civil air-defense project background to analysis the needs of the vehicle terminal hardware function and the software function. Considering the cost、size and performance of vehicle terminal system, and then formulate an overall design scheme of the vehicle terminal system, the hardware platform selects STM32 processor as the core and μC/OS-Ⅱ operating system as the core of software platform. This thesis increases the innovative design of GPRS communication module, using its software design can improve the frequency of position reporting, to achieve the function that the position information can be reported in seconds, so the command center will get real-time location information of the user terminal.Secondly, this thesis gives the specific design of the vehicle terminal system. The hardware system mainly consists of terminal antenna and terminal host, and then gives specific circuit design of the two parts. The terminal antenna mainly gives the specific circuit design of base band signal processing module. The terminal host mainly consists of protocol processing unit、GPRS communication unit、WIFI communication unit and power management unit, and then gives specific circuit design of each unit. The software part adopts μC/OS-Ⅱ operating system for the design of application. Firstly, this thesis complete the transplantation of μC/OS-Ⅱ operating system based on the STM32 processor. Secondly, it focuses on the application software design of vehicle terminal system, this thesis gives the detailed design process of initialization function、main loop structure and GPRS communication module and then complete the writing of the part program in the end.Finally, the whole vehicle terminal system will be tested in this thesis. Including positioning function、short message communication function、GPRS communication function and so on, using BeiDou debugging assistant software to test each module, and to analyze the result of each functional module, the result basically meet the design expectation, the function of vehicle terminal system can be implemented properly. Meanwhile, this thesis gives the summarization of whole subject and puts forward looking to the future work. |
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