The Study Of Effect On AIS Dynamic-precontract Mode

Automatic Identification System , short for AIS, has development for the use of ships identification ,track and communication since 1990s. As the new ship equipment, it helps to assure navigation safety. In the pulse of International Telecom Union(ITU), International Marine Organization(IMO) and International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA), AIS is becoming a standard in Marine, named ITU-R M.1371.AIS broadcasts data at regular and short intervals, with which the ship can be identified and tracked. Further data can be transmitted to provide additional information on the ship's motion, navigational state, intended voyage and cargo. The transmissions can be received by every interested party having an appropriate receiver both at sea and ashore. With these functions, AIS provides new, accurate and detailed information to maritime traffic, which is relevant not only to ship/ship but also to land/ship interaction. What's more, AIS can provide many other communication functions.In fact AIS is the mobile wireless communication. It adopts many communication technologies, .the paper researches these technologies . The first ,it introduces AIS ' development, the application in the future and its work modeli the function .and emphasize on its dynamic- precontract mode. The second, on the base of the communication technologies, for example GMSK , CRC, HDLC and SOTDMA, analyze their influence for AIS. Establish the AIS ' standard and communication model .SOTDMA is the key theory. At last , then analyses AIS communication performances in theory and make simulation, for false-slot ,put forward the disposal to reduce collision .by those analysis ,get the and gives some advise for the better application.