Methods for Processing and Interpretation of AIS Signals Corrupted by Noise and Packet Collisions

The authors deal with the operation of Automatic Identification System (AIS) used in the marine traffic monitoring to broadcast messages containing information about the vessel: id, payload, size, speed, destination etc., meant primarily for avoidance of ship collisions. To extend the radius of AIS operation, it is envisaged to dispose its receivers on satellites. However, in space, due to a large coverage area, interfering factors are especially pronounced − such as packet collision, Doppler’s shift and noise impact on AIS message receiving, pre-processing and decoding. To assess the quality of an AIS receiver’s operation, a test was carried out in which, varying automatically frequency, amplitude, noise, and other parameters, the data on the ability of the receiver’s ability to decode AIS signals are collected. In the work, both hardwareand software-based AIS decoders were tested. As a result, quite satisfactory statistics has been gathered − both on the common and the differing features of such decoders when operating in space. To obtain reliable data on the software-defined radio AIS receivers, further research is envisaged.