# Stochastic Modeling of Smartphones GNSS Observations Using LS-VCE and Application to Samsung S20
## 4 Experimental Results
### Noise Assessment of Samsung S20  
In this section, two Samsung S20 devices, namely Samsung S20 Black (S20B) and Samsung S20 White (S20W), were placed close to each other on a pillar with the true coordinates making a very short baseline (about 5 cm). The data were collected on 4 February 2023 for 3 h from 00:30:00 to 03:30:00 UTC with a sampling interval of 1 s (10,800 epochs). Figure 1 shows the location of the two Samsung S20 smartphones which are on top of a geodetic pillar with known coordinates on the rooftop of the civil engineering building (pillar N2), University of Calgary, Calgary, Canada. Table 2 provides the coordinates of pillar N2 and Table 3 gives a brief summary of the experiment. The Samsung S20 is a smartphone that supports both L5 and E5a frequencies for GPS and Galileo, respectively. However, the Galileo observations, including E1 and E5a frequencies, were not logged in the collected dataset for some unknown reason. Furthermore, there were only a few GPS satellites with L5 signals observed throughout the entire data collection period. Hence, our attention will be directed toward the single-frequency GPS and GLONASS observations. As the proposed smartphone stochastic modeling approach relies on employing the DD observations, we need to first analyze the availability and continuity of GNSS observations from both devices, as well as the common satellites between the two devices. Figure 2 provides the GNSS carrier phase continuity on the L1 frequency for the two devices. In this figure, the red dots denote the epochs in which the carrier phase observations were missing while the code observations were still observed. This figure indicates that the carrier phase continuity is different for the two Samsung S20 devices. \begin{table}
\begin{tabular}{c c} \hline
**Pillar** & **N2** \\ \hline Y (m) & \(-\)1,641,898.085 \\ \hline Y (m) & \(-\)3,664,875.558 \\ \hline Z (m) & 4,939,969.351 \\ \hline Lat. (Deg.) & 51.07942671 \\ \hline Lon. (Deg.) & \(-\)114.13282014 \\ \hline H (m) & 1116.589 \\ \hline \end{tabular}
\end{table} 
Table 2: True coordinate of pillar N2. Figure 1: Two Samsung S20 smartphones generate a very short baseline. \begin{table}
\begin{tabular}{c c} \hline
**Device** & Samsung S20 Black (S20B) and Samsung S20 White (S20W) \\ \hline
**Constellations** & GPS (Yes), GLONASS (Yes), Galileo (No observation recorded), BeiDou (Yes), and QZSS (Yes) \\ \hline
**Mode** & Static \\ \hline
**App logger** & GnssLogger (v3.0.5.6) \\ \hline
**RINEX converter** & UofC CSV2 RINEX tool [33] \\ \hline
**Date** & 4 February 2023 \\ \hline
**Duration** & 3 h \\ \hline
**Sampling interval** & 1 s \\ \hline \end{tabular}
\end{table} 
Table 3: GNSS data information. According to the figures, GPS and GLONASS are common constellations between two devices with an adequate number of tracked satellites, while the BeiDou does not provide enough observations in the S20B dataset. To continue, we will therefore focus on the noise assessment of GPS and GLONASS observations on the L1 frequency. Shown in Figure 3 are the C/N0 values for GPS and GLONASS on the first frequency for both devices. The plot reveals that the performance of the two Samsung S20 devices is almost similar in terms of the recorded C/N0 values. Figure 4 also illustrates the total number of common GPS/GLONASS satellites between Samsung S20 Black and Samsung S20 White on the L1 frequency. The geometry of GPS and GLONASS satellites in view is also presented in the Sky plot in Figure 5.  
Figure 2: GPS, GLONASS, and BeiDou carrier phase continuity for S20B and S20W. Figure 4: Total number of common GPS and GLONASS satellites between S20B and S20A on L1 frequency. Figure 3: C/N0 values for GPS and GLONASS on the first frequency for both devices. Following the assessment of the consistency of the C/N0 and the number of common satellites between the devices, we obtained the DD code and carrier phase observations for GPS and GLONASS. PRN 06 and PRN 20 were selected as the reference satellites for GPS and GLONASS, respectively.