Scintillation Effects related to Propagation Geometry as applicable to Indian SBAS

The propagation geometry involving the satellite-to-receiver ray path and the magnetic field line plays an important role in determining the effects of equatorial ionospheric irregularities. An extensive study has been conducted involving eighteen GAGAN Reference Stations extending from the magnetic equator through the northern crest of the EIA and beyond in the Indian longitude sector. Propagation angle maps have been generated using IGRF models for each station. GPS scintillation observations show effects of links viewing irregularities 'end-on' resulting in intense scintillations (S-4 >= 0.6) at regions of maximum propagation angle even with reduced irregularity intensity.