Enhancing the Kinematic GPS Solution by Ionosphere Model

Mostafa RABAH, Mahmood ELMEWAFEY, Ashraf BESHR, Faten REDA

Abstract: Kinematic precise positioning is one of the main constraints of Global Positioning System. Double differencing and Precise Point Positioning method (PPP) is the most accurate positioning in GPS committee. The ionospheric delay in the propagation of global positioning system (GPS) signals is one of the main sources of errors in GPS precise positioning and navigation. This error is cancelled in PPP approach by ionosphere free combination and reduced relatively in the approach of double differencing in case of short line (50 km), what about base line over 50 km. In this paper, Ionospheric delay has been eliminated with the availability of global or local ionospheric maps produced by varies organizations (e.g., International GNSS service (IGS)). [1], evaluate the ionospheric correction by Global Ionospheric Maps, provided in (IONEX) files produced by IGS. He shows that there is no significant effect of the provided GIM values on the solution of kinematic processing. The primary goal of this paper is to test the effect of evaluated Global Ionospheric Maps (GIMs), Modified?GIM, on precise relative kinematic positioning over varies baselines lengths extended up to hundreds km throughout comparing the relative kinematic solution with modified GIM for several baselines and kinematic PPP solution for the rover station. More accurate results were obtained by correcting ionospheric error over kinematic solution of many baseline lengths up to 300 km. The kinematic PPP solution for the rover stations was evaluated. It can be concluded that, PPP still the more accurate than relative approach even after correcting ionospheric error over longer baseline.

Keywords: DGPS, Global ionospheric maps ?GIM?, kinematic PPP, Long baselines