Variation of elevation angle and total electron content (TEC) and profile shape using Modified Jones 3D Ray Tracing for differential Global Positioning System (dGPS) in equatorial

The difference in ionospheric delay between paths to the reference and mobile stations for differential GPS has been quantified for equatorial region. This small additional ionospheric error can be evaluated and predicted for the mobile station by means of a determined differential delay along the baseline so that accurate correction can be made for the most precise positioning. In this paper we studies the ionospheric delay on the Global Positioning System (GPS) signal due to the variation of elevation angle and variation in total electron content (TEC) and ionospheric profiles utilizing the Modified Jones 3D Ray Tracing method. The differential delay can be determined for any azimuth angle of propagation and for any baseline direction, providing the approximate difference in line-of-sight (LOS) between the stations. Result show that the variations of elevation angle and TEC give effects on the difference in delay between the two stations in differential GPS (dGPS). This analysis determined the difference in ionospheric delay expected over a short baseline so that a more accurate differential GPS correction can be made.