## 4 Conclusions  
In this paper, the authors investigate the use of UIC cables, already present onboard most trains, to send high-speed data to be used as additional services for passengers or security/safety setups. This study shows that, in old trains, it would be possible to include new services that need high-speed data communication without the need for installing additional cable harnesses. These services can be related, for instance, to infotainment for passengers, onboard safety and so on.  
The analysis is carried out taking into account all fundamental functions of the UIC cables in order to guarantee that the relative signals are not disrupted by the additional data transfer required to implement a broadband power line transmission. The results show that the signal integrity of pre-existing data is kept, and that a high-speed connection is achievable using the multicarrier modulation schemes typical of the PLC broadband modems. The analysis assumes certain noise levels (that are not measured) and gives guidelines for the correct design of the system. In particular, the results reported in this work give a detailed characterization of the multiconductor cable as a communication medium in the MHz frequency range, and show that to guarantee a high quality of communication, the use of a repeater every three hauled stocks is needed.  
Conceptualization, methodology, software, validation, formal analysis, writing S.B. and M.T., supervision, F.R.  
This research received no external funding.  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**SNR (TX)** & **25 db** & **30 db** & **35 db** & **40 db** & **45 db** & **50 db** & **55 db** & **60 db** \\ \hline \(L=25\) m & \(6.59\times 10^{-3}\) & \(6.42\times 10^{-4}\) & \(1.53\times 10^{-5}\) & \(3.28\times 10^{-8}\) & \(1.05\times 10^{-12}\) & 0 & 0 & 0 \\ \(L=50\) m & \(6.84\times 10^{-2}\) & \(2.84\times 10^{-2}\) & \(7.78\times 10^{-3}\) & \(1.10\times 10^{-3}\) & \(5.10\times 10^{-5}\) & \(3.50\times 10^{-7}\) & \(8.45\times 10^{-11}\) & \(5.43\times 10^{-17}\) \\ \(L=75\) m & \(1.72\times 10^{-1}\) & \(1.13\times 10^{-1}\) & \(6.31\times 10^{-2}\) & \(2.78\times 10^{-2}\) & \(8.53\times 10^{-3}\) & \(1.46\times 10^{-3}\) & \(9.35\times 10^{-5}\) & \(1.12\times 10^{-6}\) \\ \(L=100\) m & \(2.66\times 10^{-1}\) & \(2.10\times 10^{-1}\) & \(1.53\times 10^{-1}\) & \(9.95\times 10^{-2}\) & \(5.55\times 10^{-2}\) & \(2.45\times 10^{-2}\) & \(7.55\times 10^{-3}\) & \(1.29\times 10^{-3}\) \\ \(L=125\) m & \(3.36\times 10^{-1}\) & \(2.90\times 10^{-1}\) & \(2.39\times 10^{-1}\) & \(1.84\times 10^{-1}\) & \(1.31\times 10^{-1}\) & \(8.25\times 10^{-2}\) & \(4.40\times 10^{-2}\) & \(1.81\times 10^{-2}\) \\ \(L=150\) m & \(3.84\times 10^{-1}\) & \(3.49\times 10^{-1}\) & \(3.08\times 10^{-1}\) & \(2.60\times 10^{-1}\) & \(2.08\times 10^{-1}\) & \(1.55\times 10^{-1}\) & \(1.05\times 10^{-1}\) & \(6.20\times 10^{-2}\) \\ \(L=175\) m & \(4.01\times 10^{-1}\) & \(3.71\times 10^{-1}\) & \(3.34\times 10^{-1}\) & \(2.90\times 10^{-1}\) & \(2.41\times 10^{-1}\) & \(1.89\times 10^{-1}\) & \(1.38\times 10^{-1}\) & \(9.01\times 10^{-2}\) \\ \hline \end{tabular}
\end{table}
Table 2: Bit error rate as a function of SNR at the transmitter and distance.  
Figure 15: Bit error rate as a function of SNR at the transmitter and distance.