Correlation analysis between ionospheric scintillation levels and receiver tracking performance

Rapid fluctuations in the amplitude and phase of a transionospheric radio signal caused by small
scale plasma density irregularities in the ionosphere are known as scintillation. Scintillation can
seriously impair a GNSS (Global Navigation Satellite Systems) receiver tracking performance, thus
affecting the required levels of availability, accuracy and integrity, and consequently the reliability of
modern day GNSS based applications. This paper presents an analysis of correlation between
scintillation levels and tracking performance of a GNSS receiver for GPS L1C/A, L2C and GLONASS L1,
L2 signals. The analyses make use of data recorded over Presidente Prudente (22.1S, 51.4W, dip
latitude 12.3S) in Brazil, a location close to the Equatorial Ionisation Anomaly (EIA) crest in Latin
America. The study presents for the first time this type of correlation analysis for GPS L2C and
GLONASS L1, L2 signals. The scintillation levels are defined by the amplitude scintillation index, S4 and
the receiver tracking performance is evaluated by the phase tracking jitter. Both S4 and the phase
tracking jitter are estimated from the post correlation In-Phase (I) and Quadra-Phase (Q) components
logged by the receiver at a high rate. Results reveal that the dependence of the phase tracking jitter
on the scintillation levels can be represented by a quadratic fit for the signals. The results presented in
this paper are of importance to GNSS users, especially in view of the forthcoming high phase of solar
cycle 24 (predicted for 2013).