Ionospheric deformation of broadband GNSS signals and its analysis with a high gain antenna

The ionospheric delay of global navigation satellite systems (GNSS) signals typically is compensated by adding a correction value to the pseudorange measurement. We examine the ionospheric signal distortion beyond a constant delay. These effects become increasingly significant with increasing signal bandwidth and hence more critical for the new broadband navigation signals. By simulation, we first demonstrate that the signal modulation constellation diagram is particularly susceptible to the influence of the ionosphere already at moderate electron content. Using high gain antenna measurements of the Galileo E5 signal, we then verify that the expected influence can indeed be observed and compensated. A new method based on a binned maximum likelihood estimator is derived to estimate the total electron content (TEC) from a single frequency high gain antenna measurement of a broadband GNSS signal. Results of the estimation process are presented and discussed comparing to common TEC products such as TEC maps and dual-frequency receiver estimates.