Extraction Of The Track Frequency Shift Signals Based On The Algorithm Of The Filter-envelope And Wavelet Ridge

As the train speed and density is great improved, the passing ability and transportation safety of train during the transmission play an important role on the high efficiency and normal operation of whole rail net. How to quickly, accurately and reliably demodulate characteristic information of the track frequency-shift signal (FSS) will have a direct impact on train punctuality and safety, it's also the current development direction of the track FSS demodulation. In order to demodulate the carrier frequency and the low modulation signal from the track FSS, the former research works were discussed. The works in this paper are as follows:There are two kinds of track FSS in our country now. They are 18-information track FSS and signal UM71. All of them are frequency-shift-key signal. The differences between them are in the carrier frequency and low modulation signal. This paper introduced the knowledge of the track FSS at first, and discussed the parametric selection of the track FSS. Then, the disturbances existing in the detection of the track FSS was discussed and the demand for the frequency resolution of the system parameters detection was given.The spectrum of the 18-information FSS shows two peaks and the carrier frequency is the average of the two peak frequency. The signal UM71 has only one peak and the carrier frequency is the peak frequency. This paper took advantage of power spectrum analysis to extract the carrier frequency of the track FSS. According to the characteristic of the switching frequency of upper and down side frequencies showing modulation signal frequency the filter-envelope technology was used to demodulate the FSS and the feasibility of the algorithm was analyzed.Noticing the ridge features of the FSS showed on transform domain, wavelet ridge technology was employed to extract characteristic parameters for the signal UM71, and the effectiveness of using wavelet ridge to extract FSS was also verified.Finally, according to two methods of demodulation had been mentioned in this paper, an integrated logical operation was adopted to improve the reliability of the signal demodulation and to avoid schematic miscarriage caused by interfering signal.