Ionospheric scintillation receiving algorithm based on open-loop tracking

Abstract

Rapid and random temporal fluctuations in amplitude and phase of signal caused when GNSS signals are propagating through irregularities in electron density of the ionosphere are called amplitude and phase scintillation. Ionospheric scintillation can degrade receiver tracking performance, and in extreme cases, out of lock entirely. The effect of amplitude scintillation on the signal is similar to that of a weak signal. The effect of phase scintillation on the ionosphere is similar to that of high dynamics. When the signal propagates in such an environment, traditional close-loop needs to increase the coherent integration time(T) and loop bandwidth(B) for tracking the signal, which increases the B*T value and affects the loop stability. The signal parameters of the open-loop structure are not fed back. In the condition of ionospheric scintillation, it allows longer integration time to increase the robustness of loop. Compared with traditional close-loop algorithm, ionospheric scintillation receiving algorithm based on open-loop tracking can reduce carrier cycle slips under moderate and strong scintillation. In the strong scintillation, the number of carrier cycle slips reduced 67%. In the weak scintillation environment, the equivalent effect of traditional close-loop algorithm can be obtained. When the receiver under certain dynamics, the open-loop algorithm can keep a good tracking of ionospheric scintillation signal, the traditional close-loop algorithm is very easy to lose lock. This study can provide some reference for the design of the receiver.