In 2016, an application programming interface was added to the Android operating systems, which enables the access of GNSS raw observations. Since then, an in-depth evaluation of the performance of smartphone GNSS chips is very much simplified. We analyzed the quality of the GNSS observations, especially the carrier phase observations, of the dual-frequency GNSS chip Kirin 980 built into Huawei P30 and other smartphones. More than 80 h of static observations were collected at several locations. The code and carrier phase observations were processed in baseline mode with reference to observations of geodetic-grade equipment. We were able to fix carrier phase ambiguities for GPS L1 observations. Furthermore, we performed an antenna calibration for this frequency, which revealed that the horizontal phase center offsets from the central vertical axis of the smartphone and also the phase center variations do not exceed 1–2 cm. After successful ambiguity fixing, the 3D position errors (standard deviations) are smaller 4 cm after 5 min of static observation session and 2 cm for long observation session.

On 6 September 2017, an X-class flare of the magnitude 9.3 occurred around noon UT, being the strongest flare event in a decade. The flare itself was the highlight of a quite interesting phase of solar-terrestrial interactions caused by the active region known as the Catania sunspot group 46 or active region number 2673 on the NOAA catalog. From 3 to 13 September 2017 strong flare activities occurred, accompanied by a number of radio bursts and earthward-directed coronal mass ejections. Solar wind influences at Earth were modest during the flare activity and limited to the polar regions (Linty et al., 2018, https://doi.org/10.1029/2018SW001940). But, the strong X9.3 flare itself had impacts on the dayside ionosphere causing some problems in navigation services as we present within this paper. The event data observed and analyzed give us the opportunity to improve our understanding of strong and extreme space weather events and allow us to distinguish between the influence of the different event classes on our technological infrastructure within periods of strong solar activity. Here we will discuss our observations with special focus on the X9.3 flare event and provide examples how the flare itself influenced services in the domains of aviation and maritime navigation in the European sector.

During the intense solar radio bursts on 6 September 2017, Global Navigation Satellite Systems (GNSS) signal interferences were observed at ground stations in the European longitude sector from 20°N to 70°N for all GNSS satellites in view including GPS, GLONASS, and Galileo. The solar radio noise reduced the signal‐to‐noise ratio with clear frequency dependence. The impact of the radio burst has been found at L2 and L5 frequencies, but not at L1 frequency. The ground observation of the solar radio spectrum between 1.0 and 2.0 GHz corresponds well to such frequency dependence. The maximum signal‐to‐noise ratio reduction of ‐10 dB was found when the solar radio flux was pulsating around 2,000 solar flux unit level. Precise point positioning results show that accuracy is reduced with stronger deviation for dual‐frequency solutions than for single‐frequency solutions based on L1 signal only. The positioning error refers rather to the solar extreme ultraviolet flare than to solar radio interferences. The results presented here are a clear indication of frequency‐dependent GNSS performance degradation during strong space weather events.

Global Navigation Satellite Systems’ (GNSS) carrier phase observations are fundamental in the provision of precise navigation for modern applications in intelligent transport systems. Differential precise positioning requires the use of a base station nearby the vehicle location, while attitude determination requires the vehicle to be equipped with a setup of multiple GNSS antennas. In the GNSS context, positioning and attitude determination have been traditionally tackled in a separate manner, thus losing valuable correlated information, and for the latter only in batch form. The main goal of this contribution is to shed some light on the recursive joint estimation of position and attitude in multi-antenna GNSS platforms. We propose a new formulation for the joint positioning and attitude (JPA) determination using quaternion rotations. A Bayesian recursive formulation for JPA is proposed, for which we derive a Kalman filter-like solution. To support the discussion and assess the performance of the new JPA, the proposed methodology is compared to standard approaches with actual data collected from a dynamic scenario under the influence of severe multipath effects.

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