Examining the tolerance of GNSS receiver under the effects of severe ionospheric scintillation conditions based on PLL tracking loop bandwidth

This work aims to evaluate the performance of Phase-Locked Loop under the presence of distinct scintillation patterns in the signal. Scintillation is very common in low-latitude regions due to the ionospheric dynamics. Under strong scintillation scenario the occurrence of deep fading events is usually registered and may cause severe degradation in the communication. The investigation conducted in this work uses the amplitude scintillation index S4, the decorrelation time \tau0, and the bandwidth Bn as main parameters. The study evaluates 54 different combinations of these parameters. The results indicate that in order to minimize the occurrence of cycle slips in the output phase of the Phase-Locked Loop, the most appropriate tracking loop bandwidth Bn depends on the both values of S4 and \tau0, which characterize the scintillation fading pattern. Simulations showed that as the S4 index increases, the automatic increment in the PLL bandwidth may not be the best choice as the performance depends on the temporal characteristics of the scintillating signal. The analysis showed that, among the configurations tested, the equivalent noise bandwidth of 10 Hz achieved the best performance overall. The investigation also showed that choosing the wrong parameter regarding the PLL bandwidth may increase the probability of cycle slip by up to 10 times during fading events.