## 4 Discussion  
The coordinates derived from measurements and subsequent data processing were assessed for uncertainty. The proposed algorithm computed the track axis coordinates at each epoch, enabling direct comparison with the axis positions from the primary receivers AC and BC.  
Figures 8-11 illustrate representative examples of the measurement system's performance under various field conditions. Each figure displays a series of consecutive measurements for all six receivers, accompanied by the corrected positions of the central receivers, _Acorr_ and _Bcorr_, as computed by the algorithm. Uncertainty crosses denote the CQ2D values for individual measurements. Additionally, results classified as valid (T) and included in the corrected central-receiver calculations are distinguished from those deemed erroneous (F) and excluded from further analysis.  
Figures 13 and 14 highlight instances where measurements exhibit clear positional errors despite relatively low CQ2D values. In Figure 13, all AC receiver readings are affected, and in Figure 14, three AR receiver readings show similar discrepancies. Had uncertainty been judged solely by CQ2D, these erroneous measurements would have been accepted as accurate, even though their actual deviations from the true positions far exceed what the CQ2D values imply.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Mean** & **Standard Deviation** & **Minimum** & **Maximum** \\ \hline
**Session** & \(\mathbf{\mu_{\Delta U}}\)**[\%]** & \(\mathbf{sd_{\Delta U}}\)**[\%]** & \(\mathbf{min_{\Delta U}}\)**[\%]** & \(\mathbf{max_{\Delta U}}\)**[\%]** \\ \hline
1 & 80.7 & 14.0 & 0.051 & 98.1 \\
2 & 81.9 & 23.7 & 0.012 & 99.4 \\
3 & 85.81 & 16.1 & 0.002 & 99.6 \\
4 & 86.9 & 5.1 & 66.7 & 98.2 \\
5 & 76.2 & 23.5 & 0.0004 & 99.6 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Basic statistics of the \(\Delta U\) indicator for individual measurement sessions.  
Figure 12: Relative reduction in the expanded uncertainty of the fixed base, \(\Delta U\)**(left plots)**; histograms of expanded uncertainty, \(\Delta U\)**(right plots)**.  
Figure 14: Selected results of measurement—case II.  
Figure 13: Selected results of measurement—case I.  
Simultaneously, these figures also display measurements with substantially higher CQ2D values--specifically, receiver AL in Figure 13 and receiver BL in Figure 14--that the algorithm identified as valid and included in the computation of the corrected positions for receivers A and B.  
Figure 15 further illustrates the relative nature of the CQ2D parameter: measurements with similar CQ2D values are sometimes accepted as correct and sometimes rejected, based solely on each measurement's actual deviation and its consistency with other data, rather than on the CQ2D value alone.  
Figure 16 illustrates a notable scenario in which receiver AR exhibits relatively high CQ2D values while other receivers show much lower CQ2D. At the same epoch, measurements from BL, BC, and BR are all rejected as incorrect despite their low CQ2D values. Consequently, no corrected position for receiver B is computed, as it fails to satisfy the predefined quality criteria.  
Figure 15: Selected results of measurement—case III.