A short note on estimates of position coordinates of NavIC during an intense geomagnetic storm day at Indore.

Abstract:

This paper presents an observational analysis of the accuracy of the position estimates of NavIC (IRNSS satellites) at Indore which is a low-latitude region located near the equatorial anomaly crest of the Indian subcontinent. The positional accuracy of any satellite-based navigation system is predominantly affected by the ionospheric time delay, which in turn is a function of the Total Electron Content (TEC). During a geomagnetic storm or ionospheric disturbance period, there is a significant enhancement in the TEC especially in the low-latitude regions of the Indian subcontinent which has a significant influence over ionospheric time delay and can affect the positional accuracy. However, this is only affecting the single frequency position estimations as the real-time actual ionospheric corrections can be possible using dual frequencies. Since the dual-frequency receivers are usually used for safety-critical and precise positioning applications, it is essential to evaluate the performance of the NavIC system as an alternative to the existing GPS navigation system. The sampling analysis of position estimates before and after storm time is also presented here to validate the above-mentioned statement. The position measurements (lat-lon-alt: co-ordinates) for one instant of geomagnetic storm period (September 8, 2017) is analyzed and are compared with a geomagnetically quiet day (September 9, 2017) observed during the same month and degradation of position accuracy based on varied impact of geomagnetic conditions calculated. Moreover, the data of position estimates has been sampled to two parts during the (storm time)T_s i.e., 15-18 UT and before the T_s during 3-6 UT. The error in the position accuracy of latitude, longitude and altitude is observed to be 1.0273m, 1.5789m and 1.9905m respectively on the storm day.