A separation algorithm for satellite-based AIS received signals based on SSA and RobustICA
[Objective]In high-density traffic areas,ship collision automatic identification system(AIS)sig-nals often occur,so high requirements are put forward for the separation performance and real-time perform-ance of the receiver.[Methods]For mixed signals with different signal-to-noise ratios(SNR),a separation algorithm S-RICA based on singular spectrum analysis(SSA)and robust independent component analysis(RobustICA)is proposed.The Hankel matrix of the single-channel AIS signal is processed by singular value decomposition and reconstructed by time series respectively,SSA is used to replace whitening pre-processing in traditional independent component analysis(ICA),and the optimal step size of each iteration of the separa-tion matrix is calculated using the kurtosis contrast function to quickly obtain the optimal separation matrix.[Results]The simulation results show that the signal mean squared error(SMSE)value of S-RICA is stable at about 1.5 when the signal length changes,while the SMSE of fast independent component analysis(Fast-ICA)is very unstable.S-RICA has a bit error rate of 0.97×10-2 to 1.97×10-2 at a SNR of 0 dB to 9 dB,an order of magnitude improvement over RobustICA and FastICA,and an improvement of 4 dB to 6 dB over S-FICA at an SNR of 0 dB to 7 dB.The average calculation time and number of iterations of S-RICA are about 18.5 ms and 13.6 times respectively,showing obvious advantages.[Conclusions]When the sample size and SNR change,S-RICA shows better separation performance.The results of this study have certain reference value for the application of S-RICA in future satellite-based AIS systems.