Combined differential demodulation schemes for satellite-based AIS with GMSK signals

The paper presents a set of new demodulation algorithms for use in satellite systems to receive Automatic Identification System (AIS) signals, with the potential presence of other interfering signals. The combined differential demodulation scheme, referred to as CDD-n, combines n single differential demodulation schemes with appropriately selected weights. Simulation results indicate that the gain under the proposed demodulation scheme is up to 10 dB over several existing non-coherent, single differential demodulation schemes. The impact of the combination coefficients/weights, the number of single differential detectors used, the low pass filter used, the interference and phase shift on the performance are evaluated through simulation, respectively. The proposed demodulation schemes are simple and easy to implement in satellite receivers in current and future satellite networks.