# A Digitalization Algorithm Based on the Voltage Waveform of the Multifunction Vehicle Bus
## 5 Conclusions  
In order to collect and analyze MVB data more practically, an MVB voltage waveform digitization algorithm was developed, and a sampling rate for physical-layer waveforms was obtained. This algorithm is based on the edge of the voltage signal to realize the decoding of the MVB physical-layer voltage waveform, data-frame verification, and synchronization of physical-layer data and link-layer data. And, according to the position of the edge and the curve fitting method used to determine the actual zero crossing of the waveform so as to obtain four waveform features of the MVB voltage waveform--steady-state amplitude, slew rate, edge distortion, and overshoot--through experiments, the sampling rate of the MVB physical-layer voltage waveform was determined. The experimental results show that 62.5 MHz is the best sampling rate, which can balance lower data volume and higher data quality; whether under normal operating conditions or fault conditions, the MVB voltage waveform digitization algorithm can better realize waveform decoding, anomaly detection and feature-extraction functions.  
Compared to previous data-acquisition methods (125 MHz), the sampling rate determined in the study was 50% lower. However, in terms of comprehensive waveform features extracted by the digitalization algorithm, the accuracy was only reduced by 1.7%, and there was almost no difference in waveform features.  
However, in extreme fault conditions, such as terminal resistance short circuit, the data-link layer cannot obtain enough valid frame data, which results in the synchronization of this algorithm being unable to handle them.  
Additionally, the algorithm's capability to extract waveform characteristics is limited and cannot fully represent the waveform's state.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Studies** & **This Study** & **Study Based on SVM [13]** & **Study Based on MKLSVM [16]** \\ \hline Sampling rate/MHZ & 62.5 & 125 & 100 \\ Data types &
\begin{tabular}{c} Physical-layer waveform \\ and link-layer data \\ \end{tabular} & Physical-layer waveform & Physical-layer waveform \\ Waveform features & 4 & 6 & 7 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison with other studies in terms of data acquisition and processing.  
Further improvement of the algorithm's feature extraction and synchronization strategy is needed. In addition, only limited types of faults could be generated in the experiment. Diverse fault data will be helpful to improve the ability of the MVB voltage waveform digitization algorithm to handle different faults.  
Conceptualization, H.L. and Y.L.; methodology, H.L. and Y.L.; software, X.T.; validation, X.T.; formal analysis, X.T.; investigation, X.T.; resources, X.T.; data curation, X.T.; writing--original draft preparation, X.T.; writing--review and editing, H.L. and X.T.; visualization, X.T.; supervision, Y.L.; project administration, Y.L.; funding acquisition, Y.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the State Key Laboratory for Traction and Control System of EMU and Locomotive (contract no. 2022Y)Z74), China Academy of Railway Sciences Corporation Limited.  
Not applicable.  
Data Availability Statement: Data are contained within the article.  
Authors's authors are thankful to the authors.