GNSS Carrier Phase Cycle Slips Due to Diffractive Ionosphere Scintillation: Simulation and Characterization

Abstract

Ionosphere scintillation can cause significant errors in global navigation satellite system (GNSS) phase measurements. During strong scintillation and, in particular, at low latitudes, diffraction causes deep fading in signal amplitude and rapid changes in phase. Sometimes, these diffractive fluctuations are accompanied by full-cycle phase transitions, which are, in a sense, cycle slips that are present in the signal at the antenna. Additionally, the effects of noise compound with the deep fading to cause more cycle slips. These lead to significant errors in phase measurements since they cannot be directly filtered. Previous studies analyze the impact of C/N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and fading depth on cycle slip occurrence, but did not take into consideration the contribution of phase transitions. In this article, we simulate scintillation using a phase screen model in order to study the dependence of overall cycle slip occurrence (including phase transitions) on scintillation and fading characteristics, as well as the baseline signal C/N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . We, then, analyze the resulting occurrences for GPS L1, L2, and L5 carrier frequencies for a variety of equatorial scintillation conditions. We provide rate and correlation statistics on the cumulative impact of cycle slips. The results from this article have implications for the use of carrier phase measurements during strong scintillation for navigation or ionosphere remote sensing, as well as for developing algorithms to mitigate the impact of cycle slips caused by ionosphere diffraction.