THE EFFECT OF IONOSPHERE AND TROPOSPHERE ON GLOBAL POSITIONING SYSTEM OBSERVABLES

Abstract

It is generally known that the atmospheric effects on the global positioning system signals are the most dominant spatially correlated biases. The atmosphere causing errors (delaying or advancing) in GPS signals consists of two main layers, Ionosphere and troposphere. The Ionospheric bias can be mitigated using dual frequency receivers, unlike the Tropospheric bias, The Tropospheric bias cannot be removed using the same procdure. Compensation for the tropospheric bias is often carried out using a standard tropopheric model. This research aims to investigate the effects of Ionosphere and Troposphere on GPS observables. The effects of the Ionosphere and the troposphere are investigated for point positioning and relative positioning modes using single frequency and dual frequency data. The ionospheric and troposphere models represented by leica Geo office (LGO) software are implemented; they experimentally derived using available data which was observed at the central Sudan. It was found the effect of the atmospheric refractions depends on: Type of mode used (single point positioning or relative positioning). Length of the base lines. The models and the parameters adopted.