The data-aided method of signal detection and parameter estimation for mixed signals acquired by space-based AIS

The Automatic Identification System (AIS) is a maritime safety and vessel traffic system imposed by the International Maritime Organization (IMO). The system broadcasts position reports and short messages with information about the ship and the voyage. For the separation, demodulation and decoding of the mixed signals acquired by the space-based AIS, the problems of signal detection an d parameter estimation are seriously important. By utilizing some fixed sequences (the training sequence and start flag) of AIS messages, the data-aided method of detection and parameter estimation is proposed for the mixed signals acquired by space-based AIS. This method, which is simple and feasible, can simultaneously achieve signal detection and parameter estimation. The trial results show that this method can accurately detect the AIS signals from the mixed signals and estimate their parameters.