Local Ionosphere Model Estimation From Dual-Frequency GNSS Observables

A method for the removal of ionospheric effects from single-frequency non-GPS radio navigation data through the use of data collected from a single collocated dualfrequency GPS receiver is presented. The method uses a local ionosphere model to estimate the total electron content (TEC) along any line of sight that differs from the GPS satellite lines of sight. Two novel models are investigated, a thick-shell model and a thin-shell model. It is shown that the thin-shell model is more observable than the thick-shell model, and different variations of the thin-shell model are analyzed for utility in this application. A novel method for determining the Gauss-Markov dynamics model tuning parameters using the International Reference Ionosphere (IRI) model is also presented. The algorithm is tested using real GPS observables, and modest improvement is shown over an existing method.