Model Validation for GPS Total Electron Content (TEC) using 10th Polynomial Function Technique at an Equatorial Region

GPS receivers have been profitably employed by researchers for investigations into ionospheric and atmospheric science. However, a number of improvements in measurement accuracy are necessary for today’s applications. The ionosphere has practical importance in GPS applications because it influences transionospheric radio wave propagation. Total Electron Content (TEC) is one of the parameters of the ionosphere that produces the most effects in many radio applications such as radio communications, navigation and space weather. Delays in GPS signals affect the accuracy of GPS positioning. The determination of the TEC will aid in reliable space-based navigation system. By modelling this TEC parameter, the evaluation of the ionospheric error and the correction of these ionospheric errors for differential GPS can be done. Determination of the differential ionospheric error to sub-centimetre accuracy is described in this paper utilizing a developed model. An ionospheric delay model was developed to accurately determine the difference in ionospheric delay expected over a short baseline so that a more accurate differential GPS correction could be made. An ionospheric error correction model should be made applicable to any location including the equatorial region. The results showed that the developed algorithm is a function of elevation angle and TEC from the reference station path to the satellite and could give differential ionospheric delay in sub-centimetre accuracy. Key-Words: GPS, TEC, ionosphere, baseline, differential GPS, transionospheric