Abstract of Team GNSS Proposal

The phenomenon of ionospheric scintillations poses a major challenge to the SBAS system designers even after more than six decades of extensive research. Ionospheric scintillations significantly perturb both amplitude and phase of transionospheric satellite signals often resulting in complete outage of the signal leading to severe degradation of services of satellite-based communication and navigation systems which may pose life-critical conditions, particularly for high dynamic platforms like aircrafts and adversely affects different strata of modern society. In terms of the intensity of ionospheric propagation effects, the polar and equatorial regions provide worst-case scenario and results obtained in these regions serve as a benchmark for the international Space Weather community. In the present program, efforts will be made to develop a causative understanding of GNSS receivers’ failure to track the carrier phase of the received signal during deep power fades associated with intense scintillation conditions by monitoring the received GNSS signals from IGS and UNAVCO stations distributed globally as well as other regional networks. Associated TEC depletions result in high range errors and will be characterized on the basis of the amplitude, duration and spatial gradients.

Impact of ionospheric irregularities on multiple frequencies and their mutual correlations may provide an idea of the scattering mechanisms and their variabilities even across the same L-band. The spatial diversity of GNSS constellations (GPS, GLONASS, GALILEO and COMPASS) can address the issue of loss of satellites due to failure of carrier tracking loop and mitigate the impact of ionospheric scintillations on SBAS navigation. Information related to fade durations, correlation of fades across different frequencies and effect of increased satellite links on positioning errors under scintillation conditions will be extremely helpful and provide opportunities to test the principles of spatial and frequency diversity as proposed to be applied to future GNSS under intense scintillation events as expected to be frequently encountered in equatorial and polar latitudes.