Research Of High Voltage Pulse Signal Recognition Algorithm

High voltage pulse track circuit has strong anti-interference ability,and high sensitivity of shunt was always used in the orbital where is corrosion,dirt or higher ballast resistance.But in the practical application,high voltage pulse track circuit still has some problems of defective shunt,the main reason is that the real-time of signal processing is poor,and anti-interference ability of decoder is weak,it cannot meet high stability and high safety needs of track circuit,how to solve this problem is become more and more urgent.This paper aim at the defects and shortcomings mentioned above,use TMS320C6748 high speed digital signal processor to improve the real-time of signal processing,and solve the problem of high voltage pulse track circuit response slowly;Analyzed the two major factors which affect decoder signal analysis ability—random interference and impact interference,combinate with the characteristics of high voltage pulse signal and design butterworth low-pass filter and band-stop filter,reduce the random noise more than 300Hz and 50Hz impact interference which impact signal identification,improve the anti-interference ability of the decoder;Combined with the advantages and disadvantages of existed signal analytical methods,this paper use wavelet transform and cross-correlation techniques to analysis signal.In the wavelet transform part,6 layers decomposition for high voltage pulse signal use db3 wavelet base,extract the low frequency component,use energy value as the judgment of the system output;In the Cross-correlation part,do the cross-correlation calculation with collected signal and standard high voltage pulse signal,according to the extreme value of waveform give system output.Deduced the function relation between low frequency energy threshold and signal extremum threshold with the average of high voltage pulse signal,system can automatically set threshold according to the volume of signal.Using the two take two mechanism for the system output,checking datas for two times,system will give segments free signal when two processing methods all believe there is no train on orbit,system think section is busy for other situations,meeting the principle of railway system orient security.Using Matlab simulate filtering algorithm and signal recognition algorithm under different signal-to-noise ratio,verifing the reliability of algorithm.Using C language in CCSV5.5 environment write the programs of main control module,data processing module,AD acquisition module,LCD display module and communication module,transplant them to TMS320C6748 digital signal processor,and also debug them by software and hardware,low frequency energy threshold,maximum threshold.minimum threshold error within 8%,6%and 5%,less than threshold value standard 25%,system can response correctly,meet design requirements..The design ideas and methods of this paper make track circuit receiver digitized,improve the anti-interference ability of the decoder,it can solve shunt bad problems which was caused by poor anti-interference ability of track circuit.