Ionospheric Delay Estimation Using Galileo E5 Signals Only

This article presents an analysis of a ionospheric delay estimator based on dual-frequency GNSS signals that are located in very close frequency bands. The target area is mid-latitude locations, such as Europe, where a fairly simple local ionospheric delay model can be used to simplify the estimator. A total of 8 local ionospheric model are tested in different European locations under different levels of ionosphere activities (high to very high). The simulations assume that the NeQuick model is representative of the true ionospheric delay. The results show that different local ionospheric delay models can be used depending upon the location of the user: from very simple ones in Northern Europe where the ionospheric delay does not vary greatly with the ionosphere pierce point location to more advanced ones in Southern and middle Europe where the ionospheric delay can vary significantly with the pierce point location. It also shows that it can provide very interesting results in terms of ionospheric delay estimation accuracy: as an example, the ionospheric delay estimation error standard deviation at L1 in Toulouse, France, is below 50cm for a very active ionosphere (within the top 7.5% over 1931-2001).