## 4 Discussion  
Table 3 summarises the results of the accuracy analysis for three positioning variants with the Xiaomi Mi8 smartphone: autonomous GPS (SNR-dependent observation weighting); GPS/EGNOS with a smoothing window of 20 and steady state of 60 s (SNR-dependent observation weighting); and GPS/EGNOS with a smoothing window of 20 s and a steady state of 60 s (standard EGNOS weighting model). The results clarify that the GPS/EGNOS variant with the EGNOS weighting model presents the best accuracy, which may indicate a fairly good adaptation of the component observation weights to the performance of the Mi8 smartphone positioning model. Also noteworthy are the vertical results, which have a lower maximum error than the horizontal analysis. The GSP/EGNOS variant with the standard weighting model obtained the following results: \(\text{HPE}_{\text{mean}}=2.24\) m, \(\text{HPE}_{\text{std}}=1.95\) m, \(\text{HPE}_{\text{max}}=30.62\) m, \(\text{VPE}_{\text{mean}}=3.27\) m, \(\text{VPE}_{\text{std}}=2.78\) m, and \(\text{VPE}_{\text{max}}=24.48\) m. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Receiver**} & **Weighting** & \multirow{2}{*}{**HPE\({}_{\text{mean}}\)**} & **HPE\({}_{\text{std}}\)** & **HPE\({}_{\text{max}}\)** & **VPE\({}_{\text{mean}}\)** & **VPE\({}_{\text{std}}\)** & **VPE\({}_{\text{max}}\)** \\ \cline{3-8}  & **Variant** & & & & & & & \\ \hline \multirow{3}{*}{**Xiaomi Mi8**} & 1 & 3.22 & 2.66 & 55.08 & 4.39 & 4.29 & 123.29 \\  & SNR & 2.72 & 2.18 & 53.56 & 3.90 & 3.82 & 88.14 \\  & elevation & 4.70 & 3.72 & 69.08 & 6.58 & 5.63 & 96.68 \\ \hline \multirow{3}{*}{**Septentiro**} & 1 & 0.64 & 0.37 & 3.81 & 2.20 & 1.26 & 5.06 \\  & SNR & 0.62 & 0.37 & 3.81 & 2.15 & 1.29 & 5.06 \\ \cline{1-1}  & elevation & 0.66 & 0.47 & 2.44 & 2.07 & 1.11 & 4.35 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Numerical values of the accuracy analysis performed for GPS autonomous positioning with carrier-phase smoothed code observations for the Xiaomi Mi8 smartphone and the Sepentrio AsteRx2 receiver with different variants of observation weighting. All values are expressed in meters. Figure 6: HPE and VPE values for GPS autonomous positioning smoothed with carrier-phase observations for a smoothing window of 20 s with different variants of observation weighting (upper figures—Xiaomi Mi8, lower figures—Septentiro AsteRx2). The final part of the study analyses the possibility of manipulating the components of the pseudorange correction that is applied in the GPS/EGNOS positioning algorithm. This analysis aims to test the feasibility of reducing the amount of correction data applied to the smartphone, which is necessary to achieve accuracy close to the GPS/EGNOS variant. Figure 7 and Table 4 show that horizontally, the variants with RRC (range rate correction) off and Iono correction off perform well, while vertically, only the variant with RRC off produces good results. It is noteworthy that the lack of ionospheric correction has a significant impact on the mean vertical accuracy and standard deviation (\(\text{VPE}_{\text{mean}}\) = 5.00 m, \(\text{VPE}_{\text{std}}\) = 3.69 m). The largest maximum vertical positioning error is presented by the slow-correction-off variant (\(\text{VPE}_{\text{max}}\) = 39.03). For the horizontal analysis, the slow-correction-off variant (\(\text{HPE}_{\text{mean}}\) = 3.09 m, \(\text{HPE}_{\text{std}}\) = 2.57 m, \(\text{HPE}_{\text{max}}\) = 43.93 m) was unequivocally the worst. For the Sepentrio receiver, it is clear that the RRC-off variant is characterised by results close to the original EGNOS solution (\(\text{HPE}_{\text{mean}}\) = 0.39 m, \(\text{HPE}_{\text{std}}\) = 0.18 m, \(\text{HPE}_{\text{max}}\) = 1.24 m, \(\text{VPE}_{\text{mean}}\) = 0.45 m, \(\text{VPE}_{\text{std}}\) = 0.36 m, \(\text{VPE}_{\text{max}}\) = 1.97 m). For both the Mi8 smartphone and the Sepentrio receiver, the SNR-dependent weighting variant performs moderately well for both horizontal and vertical positioning.