Robust GNSS signal tracking algorithm based on vector tracking loop under ionospheric scintillation conditions

Abstract

Ionospheric scintillation can cause GNSS (Global Navigation Satellite System) signal with severe random fluctuations, leading to the loss of tracking loop, which makes the GNSS receiver unable to provide normal positioning service. This paper proposes a robust GNSS signal tracking algorithm based on vector delay/frequency lock loop (VDFLL) under ionospheric scintillation, in order to accomplish information sharing between all channels and adaptive regulation of loop noise bandwidth by using a Kalman filter, which allows it to adapt to ionospheric scintillation. Firstly it presents the basic theory of VDFLL. Then introduces the VDFLL into the anti-scintillation loop and completes the design of the anti-scintillation loop. Lastly the robust tracking algorithm based on VDFLL is implemented in a software receiver. The simulation results show that: when the scintillation index S4 is 0.9, the Doppler frequency standard deviation of the traditional scalar tracking loop (STL) is 0.4204, however, the Doppler frequency standard deviation of the anti-scintillation tracking algorithm based on VDFLL proposed in this paper is 10.6188. It can be seen that the anti-scintillation algorithm proposed in this paper has a better tracking performance under strong ionospheric scintillation situation.