Carrier Tracking Algorithm Based on Extended Kalman Filter for Inter-Satellite Link

【摘要】：正Inter-satellite link is the core technology of autonomous navigation,and the different orbits satellites are in high dynamic and low SNR environment.Traditional carrier tracking loop suffers a compromise between loop bandwidth and dynamic performance,and is difficult to satisfy both tracking accuracy and dynamic performance in high dynamic conditions.In this paper, a carrier tracking algorithm based on extended Kalman filter(EKF) is proposed.According to the linear recursive relationship among carrier phase,Doppler frequency,change rate of Doppler frequency to establish system model,and use receiver I/Q branch observations to update carrier phase estimates based on EKF theory.Carrier phase estimates are feedback to control carrier NCO to obtain carrier synchronization.Simulation and analysis results show that this algorithm has higher tracking accuracy under high dynamic and low SNR conditions,even in the case of transient signal blockage the loop can maintain lock.