Method for demodulating signals from a multi-access system able to collide and equipment for implementing same

摘要

A method for demodulating time-multiplexed signals able to mutually collide, in particular in the case of an AIS (Automatic Identification System), being a communications system between ships allows collisions between these ships to be limited and allows the maritime traffic in view from the coasts to be monitored thanks to coastal stations that listen to the communications. When these colliding signals are sufficiently “distinct” (in frequency, in power or in time), algorithms exist for discriminating between them. The demodulator offers the possibility of demodulating two colliding signals, whose collision parameters (difference in frequency, in power or their non-synchronization) are sufficiently small to make them virtually inaccessible otherwise. The method and equipment allow the satellite AIS system to utilize cases of signal collisions that were hitherto detrimental in order to improve the overall performance.