Examining the Tolerance of GNSS Receiver Phase Tracking Loop Under the Effects of Severe Ionospheric Scintillation Conditions Based on Its Bandwidth

• Published in: Radio science Vol. 56; no. 6
• Main Authors: Portella, Igor Ponte, de O Moraes, Alison, da Silva Pinho, Marcelo, Sousasantos, Jonas, Rodrigues, Fabiano
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-06-2021
• Subjects: Bandwidths; Fading; GNSS receiver; ionospheric scintillation; Parameters; Performance evaluation; Phase locked systems; PLL; Scintillation; Tracking; tracking loop
• ISSN: 0048-6604; 1944-799X
• DOI: 10.1029/2020RS007160

This study aims to evaluate the performance of phase‐locked loop (PLL) 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 study uses the amplitude scintillation index S4, the decorrelation time τ0, 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 PLL, the most appropriate tracking loop bandwidth Bn depends on the values of both S4 and τ0, 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.
Key Points
Fading depth value of −15 dB is identified as critical threshold in the cycle slips occurrence
Calculating the empirical mean time between cycle slip for each scintillation pattern and PLL bandwidth
Determining the most suitable global navigation satellite systems receiver tracking loop bandwidth for reducing the occurrence of cycle slips