Research And Simulation On Multi-beam Antenna Technology In AIS

In recent years, along with the prosperity and development of maritime trade, coastal security situation is grim, and it's imminent to strengthen maritime safety management. Research scholars proposed the use of spaceborne AIS(Full-name: Automatic Identification System) on the coastal real-time monitoring, in order to enhance nation order and stability. The research of satellite-borne AIS system has become one of the hotspots of domestic and foreign scientific researchers. The research on the spaceborne AIS system is still in its infancy, and the collision problem of the ship signal is more serious, which directly affects the performance of the signal received by the receiver.Since the 1960s, the multi-beam antenna technology has received wide attention in the satellite communication system, and gradually become a key technology to improve the performance of satellite communication system. At present, the spaceborne AIS system in our country mainly adopts the single-point coverage type antenna to receive signals. The large antenna radiation angle lead to the power loss seriously at the edge. Meanwhile the multi-antenna system equipment is bulky and the satellite load is serious. With a large number of multi-beam antenna in the satellite communication system application status and results, the thesis design and implement the multi-beam antenna technology on-board AIS system. The main contents are as follows.At first, the thesis studied the principle of AIS system and modulation and demodulation in detail. The detection probability model of onboard AIS system is deduced as a measure of the performance of onboard AIS system based on the signal collision model of onboard AIS system.Secondly, the thesis analyzed the key key advantages of multi-beam antenna and beamforming technology. Then studied the performance advantages of multi-beam antenna from both in-orbit performance and coverage performance. Finally, the application of multi - beam antenna in satellite communication system is analyzed in detail.Thirdly, Taking the four - beam antenna as an example, the modeling and realization of the four - beam antenna in the spaceborne AIS analog source system are discussed. The simulation results are compared with those of the two-beam antenna, four-beam antenna,single-antenna and dual-antenna receiver on the spaceborne AIS system,and the analysis is made.Finally, In order to more intuitively and conveniently solve the ship detection probability of the onboard AIS system and analyze the system performance, this thesis divides the onboard AIS system into modules and performs the functional analysis on the module, and then carries on the onboard AIS system front end design , Aiming to generate simulation source data, demodulation data and corresponding detection probability results by clicking the button on the page and inputting parameters. The result is simple, and it can improve the accuracy of onboard AIS The operation of the system.