Research Of Data Access Technology In AIS Terminal

Automatic Identification System (AIS) is a kind of nav-aids equipment using modern communication technology, computer network technology and so on. The ship borne AIS periodically broadcasts the dynamic and static ship navigation information from multiple sensors and GPS. This is to ensure that it is visible between ships, so as to ensure the safety of the ship and people. Currently, AIS has been basically popularized. However, most of the domestic AIS equipments are imported products, and some of them can not reach the international standards in terms of performance. It is obvious that there is still a significant gap between domestic and foreign technology.The study of data acess technology in AIS terminal that is the core of the AIS technology can help to short the gap between domestic and foreign research level.Based on international standards ITU1371-4 and IEC61162, this paper completed the following two-part work:(1) The project studies the SOTDMA series access technology and gives the detailed design process. And it realizes these algorithms by the C language in the environment of the KEIL 4.12. Finally based on AIS host system hardware platform, the project completes the data access simulation. On the basis of realizing the access technology, the project optimizes the design of the slot reuse mechanism of Class A AIS, that is to improve the ability of available slots in the case of high load channel.(2) The project studies the CSTDMA access technology and gives the detailed design process.It also realizes the algorithm with the same method of the first part. And based on this, the project designes the high accessibility CSTDMA algorithm of Class B "CS" AIS. It can raise the access rate of Class B ships while ensuring not to interfere the time-slot conflict of Class A ships. Thereby, the system can eliminate hidden dangers caused by Class B ships in waters with hign load channel can not transmit the message.This research is a part of the National Supporting Program "Key technology and system development of AIS/GNSS shipborne navigation equipment" of Dalian maritime university.