Demodulation and information recovery of AIS signal
HUANG Biao1, SHANG Junna1, LU Hui2
(1. School of Communication Engineering, Hanghzhou Dianzi University, Hangzhou 310018, China; 
2. NO.36 Reasearch Institute of CETC, Jiaxin 314001, China)

Abstract: Automatic idenification system(AIS) is already widely used in shipping communication systems to communicate between AIS base station and ship ,ship and ship,assist navigation in marine traffic management system with the intention of making marine navigation safer. Aiming at meetting the requirements of getting the original information of ships, demodulation and information recovery techniques of AIS signals were researched. Firstly, the model and the demodulation principle of AIS signal were introduced .Then the demodulation method for received AIS signal was discussed in detail and AIS signal was demodulated with the method of phase difference,the original transmitted information recvoery method based on AIS protocal specifications was presented. Finally experiments of demodulation and information recovery were done to the received AIS signal. The results indicate that the presented method is effective.
Key words: automatic idenification system(AIS); GMSK; demodulation; protocal