Performances of GPS Signal Observables Detrending Methods for Ionosphere Scintillation Studies

Ionosphere scintillation impacts GNSS receiver performance. The scintillation effects are measured by two scintillation indices, the amplitude scintillation index S4 and the phase scintillation index ??. These indices are computed from detrended signal power and carrier phase obtained from the receiver tracking loop outputs, respectively. Recent studies show that the values of these indices depend on the detrending method used to remove the non-scintillation effects. This paper presents our investigation of the error sources in the scintillation detrending methods. For amplitude scintillation, the main error source is the detrending filter group delay. For phase scintillation, inappropriate detrending filter cutoff frequency selection is the dominant error contributing factor. The paper presents the error assessment and correction techniques for both detrending methods.