# Single-Baseline RTK Positioning Using Dual-Frequency GNSS Receivers Inside Smartphones
## 5 Experimental Results
### Case 2: Smartphone Master--Smartphone Rover  
In this second case, the relative positioning is performed considering one smartphone as master device and another smartphone as rover. This represents an innovative approach where both the master and rover are mobile devices: this is a preliminary step towards cooperative positioning using GNSS signals extracted by smartphones. As was previously written, all data have been collected simultaneously with the geodetic receiver, in order to compare results considering the same satellites (signal quality and geometry distribution) and atmospheric conditions. Moreover, based on previous results, only FLOAT solutions have been analyzed. The obtained results are very promising, which are reported in Tables 7-10. Considering the L1+L5 frequencies of GPS constellation, it is possible to observe 2D positioning accuracy at less than 1 meter and accuracy of the Up component at less than 2 meters (Figure 8). Moreover, although the accuracy is not increased with respect to the single frequency solution, the standard deviations decrease to about 1 cm. Also, the RMS values are decreased, with a high improvement especially for the north and up components (from 1.147 m and 1.386 m up to 0.230 m and 0.463 m, respectively).  
When GLONASS measurements are also considered, a slightly different behaviour is observed. Although the positioning solution is similar to the GPS-only, both the accuracy and the precision decrease when dual-constellation measurements are considered (Figure 9). This means that GLONASS measurements introduce some noise in the positioning estimation. Also, RMS values are slightly worse, even if no substantial differences can be observed with respect to the previous case.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & & **L1** & & & **L1 + L5** & \\ \hline
**Component** & **Mean [m]** & **std [m]** & **RMS [m]** & **Mean [m]** & **std [m]** & **RMS [m]** \\ \hline East & \(-0.123\) & \(0.101\) & \(0.159\) & \(-0.027\) & \(0.135\) & \(0.138\) \\ North & \(0.976\) & \(0.128\) & \(0.984\) & \(0.421\) & \(0.070\) & \(0.427\) \\ Up & \(-0.167\) & \(0.809\) & \(0.825\) & \(0.386\) & \(0.506\) & \(0.637\) \\ \hline \end{tabular}
\end{table}
Table 9: Positioning results considering the GPS+GLONASS+Galileo constellations. L1+L5 frequencies are referred to only for GPS and Galileo constellations.  
Figure 8: Comparison between L1 and L1+L5 solutions considering the GPS-only constellation and ratio = 30.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & & **L1** & & & **L1 + L5** & \\ \hline
**Component** & **Mean [m]** & **std [m]** & **RMS [m]** & **Mean [m]** & **std [m]** & **RMS [m]** \\ \hline East & \(0.131\) & \(0.011\) & \(0.132\) & \(0.332\) & \(0.008\) & \(0.332\) \\ North & \(0.931\) & \(0.033\) & \(0.932\) & \(0.298\) & \(0.015\) & \(0.298\) \\ Up & \(-1.049\) & \(0.017\) & \(1.049\) & \(-1.526\) & \(0.019\) & \(1.526\) \\ \hline \end{tabular}
\end{table}
Table 10: Positioning results considering the GPS+ Galileo constellations.  
All previous results are comparable with those obtained in many other sessions that are not presented in this paper. Thus, they can be considered independent by the sessions.