Study On The Decoding Arithmetic Of The UM2000 Track Circuit Signal

For the purpose of safety and high efficiency, the high-speed train control system requires that the ground equipment can transmit substantive train control information to the train. The main standard track circuit in our country is ZPW2000 track circuit,whose signal information content is less and it is hard to achieve the train controlling of high speed and density. In 2000, our country introduces the Gallo UM2000 -TVM430 system on the Qin-Shen line. The TVM430 signal is a digital encoding signal with 27 bits, which solves the real-time and large capacity information exchange problem between the train and ground effectively.The paper studies the demodulation arithmetic of UM2000 digital encoding track circuit signal and compare the characteristic of different demodulation algorithm. And it puts forward the zero-crossing modulation algorithm based on sine interpolation fit for UM2000 signal.The paper studies the decoding framework of UM2000 signal including the following steps to achieve the decoding safely, accurately and effectively:bandpass filtering, zero-crossing detection, sliding window DFT, threshold judgement and CRC check.In order to satisfy the request of real-time feature, the short and long time window are designed for demodulating codes. Under the condition of long and short windows, the influence of sampling time and different interpolation algorithm has been analyzed. The decoding algorithm has been tested using the simulated signals with different signal to noise ratio values, the test signals produced by test box and the factual signals recorded on the scene. By the way of Matlab code simulation and Simulink model simulation, the test results show that the algorithm in this paper is accurate, feasible and practical. In the paper,the independent developped UM2000 decoding algorithm analysis software based on the Windows platform can realize offline decoding of the simulated signals, the test signals produced by test box and the factual signals recorded on the scene. Meanwhile, connecting with the test box, the software can realize the online real time decoding of the test signals.