Design And Implementation Of Locomotive Signal System

China’s railway industry is in an unprecedented period of rapid development.Railway transportation is steadily advancing in the direction of high speed,heavy load and high density.At present,most of the widely used locomotive signal systems are based on the traditional Fourier transform,zero-crossing detection and other algorithms to detect the frequency of frequency-shifted locomotive signal,which gradually fails to meet the requirements of railway safety and reliability.The faults of missing code and garbled code in locomotive signal system occur from time to time,which seriously threaten the traffic safety.This problem is particularly serious in the dense section of high-speed and heavy-haul trains.In addition,the core processor chip of the current locomotive signal system,TMS320VC33,is on the verge of shutdown and facing the risk of being eliminated.Therefore,it is urgent to upgrade the locomotive signal system.In order to solve the above problems,this paper presents the design and implementation of a new locomotive signal system.The main research contents and innovations are as follows:(1)The application of Hilbert-Huang Transform(HHT)in locomotive signal detection is studied.The important concepts of instantaneous frequency,Empirical Mode Decomposition(EMD)and data-driven self-adaptability in HHT are described in detail.The important steps of curve fitting,endpoint effect and termination condition in EMD are compared and analyzed.Aiming at the modulation mode and noise characteristics of locomotive signal,a frequency detection algorithm based on Hilbert Huang transform and a soft threshold denoising algorithm based on EMD are proposed.Computer simulation results show that the above algorithms have very high accuracy and can almost achieve zero error frequency detection under ideal noise-free conditions.The detection results under noise conditions are also greatly improved compared with existing algorithms.(2)The reliability and safety of redundant structure are analyzed by Markov chain,which provides theoretical basis for the design of locomotive signal system.In this paper,the hardware platform of locomotive signal system is designed and implemented with the core of DSP chip TMS320F28377 and the redundancy structure of double two-vote-two.The design process of the minimal system of DSP and the interface circuit of track circuit is discussed in detail.The design concept for improving the EMC of the system is adopted to ensure the stable and reliable operation of the system.After testing,the locomotive signal system designed in this paper can accurately and rapidly detect the frequency of frequency shift locomotive signal.It can effectively solve the existing problems of current equipment and significantly improve the safety of train operation.