Research And Implementation Of Key Technologies Of AIS Receivers Based On Micro-nano Satellites

With the rapid development of the global shipping business,the global coverage of the water-area supervision network and the real-time acquisition of ship information has gradually entered people’s vision.The emergence of the satellite-borne automatic identification system(AIS)has solved this problem.But the platform is transformed from ground to micro-nano satellites,which also brings many technical difficulties such as link loss,time slot collision,Doppler frequency offset and the limitations of receiver’s size and power.Among them,the time slot collision of AIS signals from different SOTDMA subnets within the receiving range of the satellite is an important cause for the loss of AIS message.Therefore,this paper focuses on the separation of mixed AIS signals.The main work of this paper are as follows:1)A blind source separation model for multi-channel mixed AIS signals is established.Based on the research of classical ICA algorithm,an information maximization collision signal separation algorithm based on Nadam is proposed to realize the effective separation of AIS signals.The algorithm uses Nesterov-accelerated adaptive moment estimation to improve the situation that the stochastic gradient descent is easy to fall into the local optimum in Infomax,which can effectively separate the collision signal.2)The algorithm of artificial bee colony collision signal separation based on L-BFGS is proposed.In the employed bee phase and onlooker bee phase,the two-loop recursion L-BFGS quasi-Newton algorithm is adopted for rapid convergence of local optimization.The algorithm has better local search ability while using the scout bee search strategy to ensure the global optimization ability of the ABC.The improved algorithm has better separation performance.3)In view of the micro-nano satellite platform,a system design scheme of satellite-borne AIS receiver was proposed.The miniaturization,low power and high reliability of the spaceborne AIS receiver are completed.Then the sensitivity,dynamic range,anti-Doppler frequency offset range and anti-collision performance of the receiver were tested.The results show that the receiver’s performance meets the design requirements.