## 4 Experimental Results  
In this section, the performance metrics, detailed in Section 2, are analyzed for the datasets collected on the vessel from the 3 rd of January to the 30 th of March 2021. For the decoding performance analysis, the original epoch rate of one second was applied. In this way, all the decoded E6B pages were considered. The empirical daily BER values versus \(C/N_{0}\) are shown in Figures 5-7 for the months of January, February, and March 2021, respectively. Consistent results are obtained with BERs achieving values around 0.5, which corresponds to a probability of a random guess, when the \(C/N_{0}\) is below 25 dB-Hz, in agreement with the results presented in previous studies (e.g., [22; 23]). As mentioned in Section 3, the receiver implements an E6B/C combined data-pilot tracking strategy. It should be noted that for other tracking approaches, for example based on a classical E6B data-only tracking, this \(C/N_{0}\) threshold assumes slightly higher values which are nonetheless below 30 dB-Hz, as examined in [22; 23]. Figure 5: Daily BER versus \(C/N_{0}\) for the month of January 2021. The dashed black line represents the theoretical BER curve assuming Gaussian noise. Different colors refer to different days of the month. Figure 6: Daily BER versus \(C/N_{0}\) for the month of February 2021. The dashed black line represents the theoretical BER curve assuming Gaussian noise. Different colors refer to different days of the month. The empirical BER curves are also compared with the theoretical BER curve obtained assuming the presence of Gaussian noise only and represented by a dashed black line. It can be observed that the empirical curves closely follow the theoretical ones. Moreover, the daily PER was evaluated and is shown in Figure 8 for the entire period under observation. The estimated daily PER is always below one percent. It should be noted that, in agreement with the results presented in [21], it was observed that the majority of the errors occur at the beginning and end of the satellite visibility period, when the \(C/N_{0}\) is lower and consequently, when, as shown in Figures 5-7, the BER is higher. Given that at high latitudes the occurrence of satellites with low elevations can be frequent, it is of interest to analyze the PDOP under the period of observation, because this parameter may also affect the Galileo E6B demodulation performance. In Figure 9, the maximum, minimum, and median PDOP daily values are shown for the Galileo satellite constellation and for all the examined days. The median PDOP curve follows a ten-day  
Figure 8: Daily PER for the period under analysis. Figure 7: Daily BER versus \(C/N_{0}\) for the month of March 2021. The dashed black line represents the theoretical BER curve assuming Gaussian noise. Different colors refer to different days of the month. periodic trend which corresponds to the Galileo periodicity and achieves values around two, thus showing a general good satellite geometry. Indeed, maximum values of PDOP above ten are related to sporadic events occurring during the daily trip of the vessel. Finally, the TTRD was evaluated considering from two to five connected satellites and shown in Figure 10. Indeed, it is of interest to assess the TTRD performance when only a few satellites are available. Note that only a few satellites simultaneously connect to the Galileo Uplink Stations (ULSs) and are able to provide HAS corrections at the same time. For this reason, a limited number of satellites was considered in the TTRD evaluation. For the analysis, the page availability estimated considering the CRC passage, as detailed in Section 2, was exploited. Figure 10: Daily mean TTRD over the whole observation period for two, three, four, and five connected satellites. Figure 9: Daily maximum/minimum and median PDOP. In agreement with the preliminary results reported in [20], it is evident that, by increasing the number of connected satellites, the TTRD values decrease.