Research On The Limit Of Interference Warning For BTM Antenna Ports

With the rapid development of high-speed railway in our country,the safety of high-speed train operation has been paid more and more attention.As an important part of Automatic Train Protection equipment,Balise Transmission Module is in a complex electromagnetic environment.In the actual operation process,the BTM may have communication failure caused by electromagnetic interference,which may further give rise to the ATP system fault alarm.Though there are equipment used to complete the real-time online monitoring and recording for the BTM electromagnetic environment noise level,it's still necessary to do further research on determining the disturbance warning limit of the BTM communication process.As mentioned above,this thesis builds a simulation model of interference warning limit,which can be used to formulate the corresponding warning limit for various kinds of different-mode voltage disturbances of BTM antenna ports.This thesis starts with the basic principle of transponder system,the composition of the transponder system,the function and technical index of each transmission interface.Then the modulation demodulation mode of transponder uplink communication is explored,which lays a theoretical foundation for the establishment of simulation model.At the same time,the decoding algorithm and principle of answering message are studied.Then according to the analyzing of the interference source and coupling path,the main harassment coupled to antenna port can be determined as various different-mode harassment from the surrounding space.Also the correctness of this conclusion is verified by experiment.Based on the principle of transponder and the principle of magnetic field coupling between transponder antenna and receiving antenna,there will be "ghost response" when only interference exists.While this situation has been well solved after the ATP internal software upgrade,this thesis can focus on the value of interference limit in the presence of interference and useful signal.Meanwhile,the simulation model of packet reception for BTM antenna is proposed,which is established by MATLAB programming.And the adjustable properties of each parameter make the model more applicable.The early warning limit of surge pulse is obtained while the theoretical analysis and experimental results show that the different-mode voltage generated by surge pulse at the antenna port will not affect the receiving of BTM message.Then the sine amplitude modulation pulse disturbance is taken as an example,and the warning limit of BTM is obtained by simulating the different-mode disturbance with the same frequency.The above simulation and measurement results prove that the simulation model can be used to formulate the warning limit of interference online monitoring.