Study On The Method Of Detecting UM71 Frequency-Shift Track Signal

Railway signal equipment is the basic equipment of railage, and is the guarantee of safe operation of train on railway. With the development of railway and the growth of train speed, the requirement of the efficient transportation and the accurate signal analysis turns to be more and more important. In order to guarantee safe operation of train and improve efficiency of transportation, it is necessary to find a more credible algorithm on railway signal analysis.In this dissertation, the method of detecting the UM71 track signal is studied, combining with the widely-used UM71 frequency-shift automatic blocking system. In order to get the UM71 track signal efficiently and remove the noises, the method of Empirical Mode Decomposition (EMD) is used to remove the noises in UM71 track signal. Aiming at the precesion of detecting and the characteristic that the spectrum of UM71 track signal only has one peak, the method of under-rate sampling is used to detect the carrier frequency, thus, the frequency of the peak's is carrier frequency. Because the UM71 track signal is a narrowband signal, the method of ZFFT is used to detect the low modulated frequency, and thus, the difference between the frequency of the peak's and the frequency of the hypopeak's is the low modulated frequency. The dissertation simulated the algorithms of denoising and detecting in MATLAB, and the result of simulation validated the algorithms'validity.Based on the algorithms of denoising and detecting, the correlative hardware circuits that take the DSP of TMS320F2812 as the core are designed, and the software flows are presented.