| TETRA digital trunked system is a special mobile communication system for commanding, dispatching and emergency communication. Dispatchers can monitor important group or a single wireless user directly by dispatching terminal, make voice and data communication with wireless user, achieve to dispatching efficient and convenient. Therefore, the dispatching terminal is an important part in digital trunked communication system.The function of video transmission in digital trunked dispatching system can send the site image information to command center. It can be used in the police, the armed police and the fire command, traffic accident investigations, and other such on-site emergency command. This can improve the ability of making decision accurately and timely. Therfore, research and development of video transmission function in dispatching terminal is great significance.First, this paper reviews the development of digital trunked dispatching system in domestic and foreign. It describes the channel bandwidth and data transmission of digital trunked system based on the analysis of digital trunking system architecture. Then, it describes the functional requirements and technical characteristics for video transmission in digital trunked system. And it detailed analysis of the whole structure of digital trunked video transmission system, signaling processes of system and data transmission, as well as business processes of video transmission. Finally, it using c++language to implement video transmission of dispatch terminal in Windows operating system based on the analysis of key technologies, used by video transmission of digital trunked system, which includes capture video data, changing the format of video data, encoding and decoding video data as well as sending the video data. It tests the video transmission function of dispatch terminal in actual digital trunked system. The result of testing meet the functional requirements of video transmission. |
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