Precise Point Positioning with Ionospheric-Free Deviation Mask under Ionospheric Scintillation in Equatorial Region

Abstract

One of the most challenging phenomena threatening the performance of satellite navigation services is ionospheric scintillation, characterized by rapid fluctuation in the amplitude and phase of the received radio signals. Although scintillation in high-latitude regions is mostly caused by refractive effect which can be eliminated by dual-frequency measurements, the non-dispersive diffractive effect experienced in low-latitude region is still hazardous. This paper introduces an improvement into Precise Point Positioning (PPP) using a cycle-slip corrector based on ionosphere-free (IF) combination and a satellite mask based on a recently introduced scintillation index called Sigma-IF for dual-frequency conventional receivers. A comparison with the index from the standard deviation of geometry-free (GF) combination is made and analyzed. A significant improvement in accuracy and continuity of PPP after applying the proposed method is presented in the results obtained from well-known IGS stations. The increasing number of dual-frequency Global Navigation Satellite Systems (GNSSs) receivers launched into the mass market is a promising enhancement to the integrity of location-based applications.