Geomagnetic Storm Effects on Indian Regional Navigation Satellite System (NavIC) Performance

The Indian Regional Navigation Satellite System (IRNSS), commonly referred to as Navigation with Indian Constellation (NavIC), is developed to deliver accurate position, velocity, and timing data across India. It operates using signals transmitted on the L5 (1176.45 MHz) and S-band (2492.028 MHz) frequencies, both of which can be affected by ionospheric irregularities. As these signals traverse the ionosphere, irregularities in electron density induce amplitude and phase scintillations, potentially degrading navigation accuracy. This study analyzes amplitude scintillation events and ionospheric disturbances during the geomagnetic storm on July 3, 2021, and their subsequent effects on NavIC receiver performance from July 3 to July 6, 2021. Using an A 314 NavIC receiver installed in the Ahmedabad region (average altitude: 53 m), the amplitude scintillation index (S4) was computed from Carrier to Noise ratio (C/N0) values for PRN 2 through Python-based data processing. Results indicate that the L1 and S bands experienced significant scintillation (S4> 0.5, 5), while the L5 band showed minimal variations. The L1 band recorded the highest scintillation intensity, with S4 values exceeding 1 during several intervals. C/N0 variations correlated strongly with satellite elevation angles, where higher elevations led to improved signal strength and reduced ionospheric delays. The L5 band demonstrated the highest signal stability, whereas the L1 band was most impacted by ionospheric fluctuations. Satellite visibility analysis revealed disruptions in GPS and NavIC signals due to geomagnetic disturbances, resulting in intermittent signal loss for NavIC satellites. Positioning errors peaked at 64. 06 meters, with the L1 band being the most affected. Additionally, solar flare activity caused data unavailability in the L1 and L5 bands, while the S-band remained relatively stable. These findings underscore the significant impact of geomagnetic storms on satellite navigation and emphasize the need for advanced signal processing techniques to mitigate ionospheric effects and enhance the reliability of NavIC-based positioning services.