Investigating 4 ms jumps in Galileo pseudorange observations from Android smartphones

Access to the raw GNSS measurements has been available on Android smartphones since 2016, and many modern devices now support multi-GNSS and multi-frequency signals, improving positioning performance. This paper investigates an anomaly observed in Galileo smartphone observations, where the pseudorange occasionally experiences 4 ms jumps, corresponding to one full code period of the Galileo E1 signal. Such jumps can degrade positioning accuracy if not detected and corrected. The European GNSS Agency (GSA) published a white paper in 2018 recommending verifying the Galileo tracking status and strongly advising developers to use only Galileo smartphone measurements with E1C 2nd Code status. However, this research demonstrates that 4 ms jumps still occur, even when the tracking status indicates E1C 2nd Code. Experimental results from the Xiaomi Mi8 and Google Pixel 8 Pro smartphones show that these jumps vary between devices and over time. Therefore, checking the tracking status alone is insufficient to prevent these jumps. A straightforward correction can be applied at the measurement level based on the difference between two consecutive epochs. We used this approach to update the UofC CSV2RINEX tool available on GitHub ( https://github.com/FarzanehZangeneh/csv2rinex ). However, this method cannot detect all jumps in some scenarios, for instance, when they occur at the first appearance of satellites or after pseudorange tracking loss. This research uses the Observation Minus Calculation (OMC) indicator to identify the undetected 4 ms jumps. The proposed approach was evaluated using kinematic data from Xiaomi Mi8 and Google Pixel 8 Pro devices with and without correction for 4 ms jumps. The results show performance improvements in the root-mean-square (RMS) and the 50 th percentile of the horizontal positioning error after applying the correction to the Galileo measurements. • Corrected 4 ms Galileo pseudorange jumps in smartphone GNSS for improved PPP accuracy • Galileo jumps observed even with proper signal lock on E1C 2nd Code • Enhanced CSV2RINEX tool released on GitHub for Galileo jump correction • Observation Minus Calculation (OMC) used to detect any undetected 4 ms jumps • Galileo jump correction reduces RMS and 50th percentile position errors