Abstract
GPS and GLONASS are currently the Global Navigation Satellite Systems (GNSS) with full operational capacity. The integration of GPS, GLONASS and future GNSS constellations can provide better accuracy and more reliability in geodetic positioning, in particular for kinematic Precise Point Positioning (PPP), where the satellite geometry is considered a limiting factor to achieve centimeter accuracy. The satellite geometry can change suddenly in kinematic positioning in urban areas or under conditions of strong atmospheric effects such as for instance ionospheric scintillation that may degrade satellite signal quality, causing cycle slips and even loss of lock. Scintillation is caused by small scale irregularities in the ionosphere and is characterized by rapid changes in amplitude and phase of the signal, which are more severe in equatorial and high latitudes geomagnetic regions. In this work, geodetic positioning through the PPP method was evaluated with integrated GPS and GLONASS data collected in the equatorial region under varied scintillation conditions. The GNSS data were processed in kinematic PPP mode and the analyses show accuracy improvements of up to 60% under conditions of strong scintillation when using multi-constellation data instead of GPS data alone. The concepts and analyses related to the ionospheric scintillation effects, the mathematical model involved in PPP with GPS and GLONASS data integration as well as accuracy assessment with data collected under ionospheric scintillation effects are presented.
Highlights
Global Navigation Satellite Systems (GNSS) are widely used nowadays for geodetic positioning, atmospheric monitoring, navigation and in scientific research, among many other activities
The differences between GPS and GLONASS are well disseminated in the literature and the most important of them is related to the signal transmission, with GPS using Code
This article presents the mathematical model involved in Precise Point Positioning (PPP) with GPS/GLONASS integration, the characterization of ionospheric scintillation through the S4 and s’ indices, as well as PPP accuracy analyses by using GPS data alone and the integration of GPS and GLONASS data collected under ionospheric scintillation effects
Summary
Global Navigation Satellite Systems (GNSS) are widely used nowadays for geodetic positioning, atmospheric monitoring, navigation and in scientific research, among many other activities. Kinematic positioning is in general degraded when a small number of satellites is available, which frequently occurs in urban trajectories or under severe atmospheric conditions, as for example, under ionospheric scintillation effects. The accuracy of the estimated position through PPP can be significantly degraded under scintillation conditions, especially in the kinematic mode This is due to the weakening of the GNSS signal caused by scintillation effects that may lead to cycle slips and even total loss of lock. The data were collected by Septentrio-PolaRxS-PRO receivers belonging to the ionospheric scintillation monitoring network deployed in Brazil as part of the EC funded CIGALA and CALIBRA projects (Vani et al, 2016) These receivers collect GNSS data, as well as the well-known scintillation indices S4 and s’, commonly used to characterize, respectively, amplitude and phase scintillation effects (Davies, 1990; Van Dierendonck et al, 1993). This article presents the mathematical model involved in PPP with GPS/GLONASS integration, the characterization of ionospheric scintillation through the S4 and s’ indices, as well as PPP accuracy analyses by using GPS data alone and the integration of GPS and GLONASS data collected under ionospheric scintillation effects
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