Research On Ionospheric Scintillation Model And Receiving Algorithm Of Satellite Navigation Signal

The ionospheric scintillation can cause fast and random jitter of the power and phase of the navigation signal.It will increase tracking and positing error of receivers.When the scintillation is severe,it will cause the receiver loop to lose the lock frequently.Sanya monitoring station has been due to strong scintillation caused by nearly 3 hours loop lock,In the case of high solar activity,the probability of occurrence of strong scintillation in the navigation signal is as high as 15%per hour,seriously affecting the integrity and continuity of the navigation system.In the traditional monitoring receiver does not deal with the ionospheric scintillation,this paper analyzes the ionospheric scintillation model and the impact on receivers and proposed a more robust reception algorithm.The work of the paper is as follows:1)Considering that multi-frequency receiving methods are used in modern navigation receivers,the traditional Cornell model is a single-frequency ionospheric scintillation model and cannot reflect the relationship between different frequency scintillation signals,A multi-frequency ionospheric scintillation model based on Cornell model is proposed.The analysis of the multi-frequency scintillation sequence shows that the scintillation sequence at the similar frequency is relatively large when the scintillation is weak;When the scintillation is enhanced,the phase scintillation sequence is rapidly deteriorated due to random Canonical fading.2)In this paper,the influence of ionospheric scintillation on the instantaneous branch of I,Q is analyzed,and the optimal bandwidth under different scintillation intensity is analyzed.When the amplitude scintillation index is 0.9,the optimal bandwidth is 14Hz.When the scintillation index is 0.6,the optimal bandwidth is 6Hz.As the scintillation intensity becomes weak,the optimal bandwidth decreases.Based on the relationship between bandwidth and scintillation,an adaptive bandwidth tracking loop based on amplitude scintillation index is designed.The simulation results show that FAB-PLL loop is equivalent to PLL(5Hz)and the phase jitter is 16.9%lower than PLL(14Hz),when the amplitude scintillation index is 0.5.When the amplitude scintillation index is 0.9,FAB-PLL loop is equivalent to PLL(14Hz)and the phase jitter is 27.5%lower than PLL(5Hz).3)Aiming at the robust carrier tracking problem of the receiver under ionospheric scintillation,an extended Kalman carrier tracking algorithm based on AR model is proposed.When the amplitude scintillation index is 0.6,the phase jitter is reduced by 36.04%compared to the EKF tracking algorithm.In the moderate scintillation(When the amplitude scintillation index is 0.5),the frequency estimation accuracy increased by 27.1%.In the strong scintillation(When the amplitude scintillation index is 0.7),the number of cycle slips is reduced by 80%,the frequency estimation accuracy increased by 33.2%.In the severe scintillation(When the amplitude scintillation index is 0.9),the number of cycle slips is reduced by 80%,the frequency estimation accuracy increased by 43.3%.The research results of this paper are of great significance to the design of a more robust ionospheric scintillation signal tracking algorithm,which is applied to the simulation of the ionization layer of the signal source,and the receiver stably scintillation signal.