GPS Navigation Solution Performance Analysis due to Solar Eclipses in the Context of Indian Subcontinent

Global Positioning System (GPS) is a satellite-based navigation system that provides three-dimensional position of a user (latitude, longitude and altitude) anywhere on or above the surface of the earth. The Navigation accuracy of GPS is affected by various errors. Among all the errors, the delay contribution is more due to ionosphere and is termed as ionospheric delay. Ionospheric delay is a function of the Total Electron Content (TEC). TEC can be determined using either the code or carrier phase measurements. TEC is defined as the number of electrons along the ray path between a transmitter and a receiver. This number is significant in determining ionospheric effects such as refraction, dispersion, and group delay on radio waves. The TEC is strongly affected by solar activity, earthquakes, Tsunami and geomagnetic activity. In this paper, an attempt is made to analyze the TEC variations along the satellite propagation path in the upper atmospheric layers during the total solar eclipse on 22nd July, 2009. The GPS receiver data from IISc, Bangalore is collected on the day of the eclipse and two days before the eclipse for analysis. Data is sampled at a sampling rate of 30 seconds for analysis. TEC is estimated for the day long data of the corresponding days and response of total TEC to the eclipse was analyzed. The results show that: 1) Eclipse led to depression of TEC mounted to 2-6TECU 2) maximum TEC depression (6TECU) occurred during eclipse maximum.3)better Navigation solution is obtained during the eclipse time.