Improved ionospheric error correction for differential GPS

Using differential GPS carrier phase techniques over a short baseline, the effect of the ionosphere can be determined at the reference station and used to correct the range measurement at the second/mobile station. In this paper, we present modelling calculations to determine differences in ionosphere-induced delay between nearby reference stations to an accuracy of a millimetre. This is so that empirical formulae can be formulated to accurately determine the difference in ionospheric delay expected over a short baseline so that a more accurate differential GPS correction can be made.