The balise transmission system (BTS) is an automatic identification system for vehicle–ground communication based on radio frequency identification (RFID) technology. The electromagnetic coupling characteristics of BTS have a very important effect on the transmission quality of the uplink telegram signals. However, signal transmission problems of BTS often occur due to unreasonable installation mode or parameter setting. In order to solve these problems, it is necessary to fully discuss the electromagnetic coupling characteristics of the BTS. In this paper, the transmission process of energy and data between the onboard antenna unit and the balise was analyzed using digital twin technology. A high-precision dynamic electromagnetic coupling model of the BTS was established from four aspects of three-dimensional structure, physical properties, behavior patterns, and rule restrictions. Then the accuracy of the model was verified by experiments. Finally, the influence of typical parameters on the uplink signal is calculated and analyzed quantitatively. The results showed that compared with other factors discussed in this paper, the vertical distance and the installation mode had greater effects on the uplink signal. These results can be used to guide the engineering installation and related optimization of the BTS.

For high-speed train, balise transmission module (BTM) system is easily interfered with by other equipment of the train. This could cause the train to malfunction. Studying the electromagnetic susceptibility (EMS) of the BTM is very important for the performance and efficiency of the train. In this paper, a modular, system-level modeling method is proposed to predict the EMS of BTM systems. Based on object-oriented technology and a modular method, the BTM system is disassembled into several modules according to the electromagnetic characteristics of the whole system rather than the physical structure. All the modules are mutually independent, and the total EMS could be evaluated by the output of them. The modules of three key elements of electromagnetic compatibility (EMC), i.e., sources, coupling paths, and sensitive equipment, are established by the theoretical method, full-wave simulation method, and black-box test method, respectively, and put into different layers. According to the functions of the BTM system, the EMS of BTM is given by analyzing the interrelation of input and output of modules. Results of the proposed model were verified by measurement.

As a key equipment of the high-speed Electric multiple unit (EMU), the Balise transmission module (BTM) is tend to be affected by electromagnetic disturbances. However, the existing filter can not well eliminate electromagnetic disturbances. In order to improve the Signal to noise ratio (SNR) of BTM uplink signal, Variational mode decomposition (VMD) method is introduced into de-noising the uplink signal polluted by disturbance. The proposed de-noising method decomposes the noise-polluted signal into several narrow band subsignals. And 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 (NSTFTWVD) method are applied to determine the decomposition mode number of the target signal. The proposed method is used to deal with both simulation signal and measured BTM uplink signal. Results demonstrated good improvement in SNR by 20dB and 12.63dB, respectively.