| Abstract |
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In Modern radio systems such as global positioning system (GPS), in which accuracy is based on Time of Arrival (TOA) of the signal, the propagation of the signal through atmospheric layers causes a delay in the arrival of the signal at the receiver. In order to access the accuracy of the system, it is required to estimate the delay of the signal in predominant atmospheric layers i.e. ionosphere and troposphere. As the delay of the signal in troposphere is independent of frequency, it is required to compute the delay of the signal in ionosphere which is frequency dependent and is function of in total electron content (TEC) in the ionosphere. The aim of this paper is to compute TEC in the line of sight of the satellite and the receiver and to estimate the vertical TEC, which is useful to image the ionosphere over low latitude region like India. The data provided by Scripps Orbit Permanent Array Center (SOPAC) for an IGS station NGRI, Hyderabad located in India at Lat/Long: 17°24'39"N/78°33'4"E for 11th September 2014 is collected and processed by using Convert software tool . In this paper, VTEC is computed using different mapping functions to investigate the suitable mapping function over the low latitude regions. |
