## 5 Quantitative Evaluation of the Influence of Some Typical Parameters on the Balise Uplink Signal  
High-quality signal transmission is the basis for ensuring the reliability of the BTS. The BTS involves many system parameters. Setting these parameters and matching different parameters is done to ensure better information transmission is not accurately  
Figure 14: Uplink field conformity test configuration. Figure 15: Validation results of the uplink field conformity test. described in the relevant specifications, standards, and previous literature, but rather relies on engineering experience. This section provides a quantitative evaluation of the influence of some typical parameters affecting the signal power coupled to the onboard uplink receiving antenna. Some typical parameters of a BTS composed of an OAU and a reduced size balise are shown in Table 4. \(x_{0}\) and \(y_{0}\) are half of the two sides of the reduced size balise antenna (including transmitting antenna and receiving antenna) along the OX axis and OY axis, respectively. \(x_{1}\) and \(y_{1}\) represent half of the two sides of the OAU (the same antenna is used for downlink transmission and uplink reception) along the OX axis and OY axis, respectively. BTS-related standards and specifications do not put forward specific requirements for the size of the onboard antennas. It only needs to pass the tele-powering field conformity test and the uplink field conformity test in the test specification. The allowable range of antenna vertical distance \(\Delta z\) is 220 to 460 mm. The antenna lateral deviation is the deviation of the OAU and the balise along the OY axis. This is usually caused by the static installation of the OAU and balise and the steering and vibration during dynamic train operation. The maximum allowable deviation is specified by the manufacturer. For the balise emission current \(i_{1}\), \(i_{1}\in[I_{\text{u2}},~{}I_{\text{u3}}]\). \(I_{\text{u2}}\) and \(I_{\text{u3}}\) are the minimum and maximum currents on the transmitting antenna when the balise is working normally, and the amplitudes are 59 and 186 mA, respectively. By calculating the parameters in Table 4, we can discuss the influence of the lateral or longitudinal installation mode, vertical distance, lateral deviation, uplink transmitting current intensity of active balise, and tele-powering signal current intensity of onboard transmitting antenna on the uplink signal of the system. Table 5 shows the definition of installation type of the OAU and the balise. The lateral means that the long side of the OAU or balise is consistent with the \(X\)-axis direction. The longitudinal means that the short side of the OAU or balise is consistent with the \(Y\)-axis direction. Figure 16 shows the corresponding layout of the balise. For the onboard receiving antenna, the uplink transmitting current of the passive balise be calculated by (20). All parameters in Table 4 can be calculated according to (14). Figures 17-22 show the variation of the signal power at the onboard receiving antenna terminal with the longitudinal displacement of the antenna under different BTS parameters. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Variable** & **Value** & **Variable** & **Value** \\ \hline \(x_{0}\) & 100 mm & \(\Delta y\) & 0 mm \\ \(y_{0}\) & 195 mm & \(i_{1}\) & 59 mA \\ \(x_{1}\) & 100 mm & \(i_{\text{d}}\) & 1500 mA \\ \(y_{1}\) & 160 mm & \(\mathcal{Q}_{\text{r}}\) & 3 \\ \(\Delta z\) & 340 mm & \(A_{\text{z}}\) & 0.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Some parameters of the BTS. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **OAU** & **Balise** \\ \hline Installation Type-1 & lateral & lateral \\ Installation Type-2 & longitudinal & lateral \\ Installation Type-3 & lateral & longitudinal \\ Installation Type-4 & longitudinal & longitudinal \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Definition of installation type. Figure 16: Schematic diagram of longitudinal and lateral balise.