Ionospheric-Constrained PPP using Triple-GNSS Constellations
Robert S.B. Galatiya SUYA
University of Malawi-The Polytechnic
The technique of Precise Point Positioning (PPP) has wide-spread application in positioning, navigation, and timing (PNT) due to its improved accuracy and low cost. However, the technique continues to suffer from long convergence period in order to attain Real-Time
Kinematic (RTK) comparable performance. The fusion of multi-GNSS constellations remains today’s most probable remedy to the long convergence time with improved positioning
accuracy, availability, redundancy and integrity. Besides, the Ionosphere and Hardware Delay
(IHD) derived from Global Ionosphere Maps (GIM) generated by the International GNSS service (IGS) have proved significant in accelerating single-frequency PPP convergence time.
Previous literature has a deficiency on triple constellation PPP incorporating both ionosphereconstrained
single frequency PPP and dual-frequency PPP. In this paper,
GPS+GLONASS+Galileo GNSS constellations are evaluated in kinematic mode over nine (9)
Multi-GNSS Experiment (MGEX) stations. Twenty-four (24) hour observations for the first
week of February, 2017 are processed in four PPP scenarios (GPS-only, GLONASS-only,
GPS+GLONASS, and triple-constellation of GPS+GLONASS+Galileo) at 7º elevation angle
cut-off. To validate the findings, standard single-frequency PPP and dual-frequency PPP are
analyzed. The results indicate that the application of GIM in ionosphere-constrained PPP
improves the overall convergence time and standard deviation with respect to standard singlefrequency
PPP. Furthermore, better convergence time is obtained in dual-frequency PPP
without virtual observations. Moreover, augmenting GPS with GLONASS and Galileo, tripleconstellation,
improves in relation with GPS-only PPP in standard single-frequency PPP,
standard dual-frequency PPP, and in ionosphere-constrained PPP. Thus, this study fills the
gap in literature by unveiling the threshold of performance for the ionosphere-constrained
PPP using triple-GNSS constellations.
Event: FIG WW 2019 Hanoi
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