The updated ionospheric delay model to improve the performance of GPS single-frequency receivers

A regional updating technique is suggested for the global ionospheric delay model (Klobuchar's [1987] model). The updating procedure uses series of va lues of the ionospheric delay (ID) which are reconstructed from distance me asurements at two Global Positioning System working frequencies. We conside r the situation where Klobuchar's model is updated from measurements from a single ground-based reference station. We exemplify the use of a regional updating of the ID model under undisturbed ionospheric conditions, as well as under solar eclipse and magnetic storm conditions. In all cases presente d, using the proposed technique the standard deviation between predicted an d measured ID values was reduced by a factor of 1.2-2.8 as compared with Kl obuchar's original model used under the same conditions. A. tentative estim ate is made of the variation in the ionospheric rms error in determining th e user's location (UPL) through the use of the regional updating technique. For the examples considered in this study, on applying the regional updati ng of Klobuchar's model, the ionospheric fms error in determining the UPL w as found to be lower by a factor of 1.3-2.6 than that obtained by using the same model without updating.