Impact of Solar Cycle 25 on GNSS measurements

As we approach the peak of Solar Cycle 25, ionospheric activity and scintillation are increasing, negatively impacting the quality of GNSS measurements and presenting challenges to positioning.

To understand the direct impact on GNSS receivers and their positioning engines, scintillation was characterised using the amplitude scintillation index (S4) and phase scintillation index (σφ) values. Additionally, the effect of scintillation on receivers was examined through the analysis of C/N0, lock breaks, double differences and other indicators. The spatial, temporal and spectral signal behaviour was also investigated.

The results showed that lower frequency GNSS signals are impacted more than higher frequency. This was demonstrated by the loss of tracking lock statistics and depth of signal fade. The amplitude scintillation intensity was also higher than the phase scintillation. During scintillation, the ionospheric delay varies with a higher magnitude compared to the calm ionosphere conditions.

What you will learn

Written by Isabelle Tremblay, geomatics designer and Ali Broumandan, resilient GNSS lead at Hexagon’s Autonomy & Positioning division, this article discusses challenges with increasing ionospheric scintillation as we approach the peak of Solar Cycle 25 and how it is affecting GNSS positioning. It describes the GNSS signal parameters we use to measure and characterise scintillation and how it affects GNSS receiver measurements and positioning. It also demonstrates the difference between the effect of scintillation on the performance of RTK and PPP.

RTK versus PPP position error during ionospheric scintillation.

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