Special Issue on “Electromagnetic Protection & GNSS for Railway Applications”
Kai-Kit Wong，University College London
Jun Fan, Missouri University of Science and Technology
Xurong Dong, International Cooperation Research Center, China Satellite Navigation Office
Kun Liang, National Institute of Metrology, China
本專欄已經在 Chinese Journal of Electronics 2020年第1期刊出。
China has made remarkable achievement in high-speed railways (HSR), which highlights the rapid development, keeping ahead in the world by the advantage of latest-developing and scale. It is no doubt that safety is the most significant to HSR. Due to inevitable electromagnetic interference (EMI) existing in HSR, which may degrade the signaling equipment performance, it is a key issue to carry out profound studies on electromagnetic environment (EME) and electromagnetic compatibility (EMC) for HSR equipment. Hence, it becomes more focused on principles and engineering of EME and EMC for HSR. As EME is consisted of space, time and spectrum components related to HSR scenario, studies on EME are based on mutual coupling of all possible EMI sources in HSR. Since HSR is a huge and complex dynamic system, EMC for HSR is a system-level issue. It involves multi EMI sources and mutual coupling of EM phenomena, the interference effect of transient disturbance, the risk detection of EMI fault during cross-line operation, EMC modeling for complex system, et al. Meanwhile, the measurement and data analysis for electromagnetic emission of HSR system, and the anti-electromagnetic technology of HSR system are also included.
Currently, the Global Navigation Satellite System (GNSS), especially Beidou has been widely used in railway system and has a bright future in more applications. On localization unit structure, multi-sensor fusion, locations integrity monitoring, indicators of the GNSS-based performance evalsuation and railway RAMS have been made several progresses, they demonstrated the concept of GNSS-based localization and its feasibility. In Europe and China, the next generation of train control systems both propose the GNSS-based train localization as part of the system, and the key for improving flexibility of it. On low-density lines, considering the construction and maintenance costs, the availability of GNSS-based train localization techniques has become the main research and highly possible deployment in the near future.
This special issue aims at summarizing the most recent research results on electromagnetic protection & GNSS for railway applications, promoting the new progress of theories and methodologies. We selected 7 papers with domains ranging from EMC modeling, the anti-electromagnetic technology, GNSS performance analysis & evalsuation, GNSS integrity fault detection etc.
The articles listed below have been included in the special issue on No.1, 2020 of CJE reflecting exciting achievements in recent years.
1. Research on Electromagnetic Compatibility of Chinese High Speed Railway System (Wen, et al. )
Research on Electromagnetic Compatibility of Chinese High Speed Railway System (Wen , et al.) discussed the EMC and the electromagnetic safety issue of Chinese HSR, which is derived from technology development mode and core technology characteristics. The limitation of the high speed train's exportation due to the lack of test method for the train's emission is also analyzed. Combining the electromagnetic environment characteristic and the development planning of Chinese HSR, several suggestions in the research of anti-electromagnetic interference, electromagnetic protection in the strong electromagnetic field and the whole large system's radiation emission test method are put forward.
2. Survey of Performance evalsuation Standardization and Research Methods on GNSS-Based Localization for Railways (Cai, et al.)
Survey of Performance evalsuation Standardization and Research Methods on GNSS-Based Localization for Railways (Cai, et al.) gives a structure survey of the performance evalsuation standardization of GNSS-based train localization. Analysis of train localization technique and its performance requirement in CTCS-3 are the basis. Then GNSS performance characteristics suggested in different transportation field are analyzed. Based on the research on the relation of these two kinds of performance, five characteristics consist of accuracy, integrity, reliability, availability and safety are proposed and research on the evalsuation approaches are investigated.
3. Optimized Fault Detection Algorithm Aided by BDS Baseband Signal for Train Positioning (Wang, et al.)
Optimized Fault Detection Algorithm Aided by BDS Baseband Signal for Train Positioning (Wang,et al.)Aiming at the influence of satellite navigation signal on the propagation processes, such as shadow and multipath effects, the fault detection algorithm based on navigation satellite system baseband signal is proposed. Experimental results show that the proposed algorithm can improve the monitoring performance of train satellite positioning integrity. The results are instructive for the study of satellite navigation positioning services for meeting the railway industry's security requirements.
4. GNSS Fault Detection and Exclusion based on Virtual Pseudorange-based Consistency Check Method (Liu, et al.)
GNSS Fault Detection and Exclusion based on Virtual Pseudorange-based Consistency Check Method (Liu, et al.) introduces a consistency check method of FDE (Fault Detection and Exclusion) for GNSS-based train positioning using the virtual satellite pseudorange data. Without relying on extra position sensors, this method breaks the limitation of classical integrity methods that require a suitable satellite visibility level to carry out FDE. Compared with the classical residual-based GNSS integrity monitoring algorithm, this method achieves a higher availability and makes the best use of GNSS measurements even under limited GNSS observing conditions.
5. Hazard Rate Estimation for GNSS-Based Train Localization Using Model-Based Approach (Lu, et al.)
Hazard Rate Estimation for GNSS-Based Train Localization Using Model-Based Approach (Lu, et al.) provides a method for hazard rate estimation of the GNSS-based train localization function, also proposes a model-based approach using GNSS localization unit working principle to study railway localization behaviors. The effectiveness of the proposed method is evalsuated by the field test data, and the risks of GNSS in a train station environment condition are analyzed.
6. An APD-Based evalsuation on the Effect of Transient Disturbance over Digital Transmission (Geng, et al.)
An APD-Based evalsuation on the Effect of Transient Disturbance over Digital Transmission (Geng, et al.) introduces a method to evalsuation the effect of transient disturbance over wireless transmission in railway system, based on the statistical characteristics of the disturbance. Relation between the bit error performance of multilevel modulated transmission and the amplitude probability distribution of the transient disturbance is established, by binary expansion of received signal. This method provides evalsuation with higher accuracy in a broader range of applications, as well as reference for emission restriction.
7. A VMD Based Improved De-noising of Onboard BTM Receiving Signal (Geng, et al.)
A VMD Based Improved De-noising of Onboard BTM Receiving Signal (Geng, et al.) introduces an improved variational mode decomposition method for signal de-noising in the balise uplink signal. This method decomposes the noise-polluted signal into several narrow band sub-signals. Then, the de-noised BTM transmitting signal is reconstructed by the sub-signals of the same frequency as the BTM carrier. To improve the accuracy of the VMD based signal decomposition, the Normalized short time Fourier Transform-Wigner Ville Distribution (NSTFT-WVD) method are applied to determine the decomposition mode number of the target signal. The proposed method is applied to the measured noise-polluted uplink signal, and the effectiveness of the method is verified.