Design And Implementation Of Application Processor Unit Of Tiantong Satellite Communication Terminals For The Marine Buoys

China’s oceans are vast and rich in resources,but the degree of exploitation of marine resources is insufficient currently.With the development of China’s technology and economy,the real-time collection and secure transmission of large-scale marine data has become an important demand for national marine security and economic development.At present,marine data transmission mainly relies on foreign satellite resources such as Iridium and maritime satellites which can’t meet the requirements of data security and confidentiality.The application of china’s self-developed Tiantong satellite provides a new program and way for maritime communications.Compared with other foreign satellites,Tiantong satellite has advantages such as high confidentiality,wide coverage,low interference and stable operation.This thesis focuses on the design and implementation of the hardware and software of the application processor unit.The application processor unit can be installed on the communication terminal of the micro buoys at sea.The communication terminal is designed and developed based on the Tiantong satellite of China,including a servo unit,an RF unit and application processor unit.The application processor unit realizes the control function of antenna tracking satellite signal beam with the servo unit.The application processor unit controls the CP(Communication Processor)module of the RF unit to connect the Tiantong satellite mobile communication network and realize real-time data transmission.The main work of the thesis is as follows:(1)In response to the demand for real-time transmission of data of the sea buoy communication terminal stably under the fourth-level sea conditions,the hardware design of the application processor unit is completed based on the FET1028A-C core board.Then the embedded system environment is built according to the actual demand.(2)The control scheme of the servo unit for the application processor unit is designed and implemented.The communication terminal uses directional antenna instead of omnidirectional antenna to obtain higher antenna transmitting gain.In the fourth-level sea conditions,the communication terminal is affected by waves to shakes irregular and violently so that the directional antenna will deviate from the best satellite communication area.The application processor unit realizes the function of real-time calculation of antenna attitude and control of servo unit to adjust antenna attitude for satellite signal beam tracking.At the same time,a communication scheme based on the lib Modbus protocol and the automatic switching function of satellite signal beam tracking mode(auto/manual)is designed and realized.(3)The communication terminal is designed and implemented to access the satellite network function.By analyzing 3GPP protocol and Tiantong satellite communication framework,the GSM07.10 protocol is used to send different types of data under the same physical serial port to realize the communication between the application processor unit and the CP.(4)Simulation tests are conducted on the communication terminal to simulate the fourth-level sea conditions,the functions of the application processor unit were tested,and the test results were analyzed.