A Fast Demodulating Method for Frequency Shift Signal Based on Fractal Box Dimensions Theory

According to the practical requirement of railway site, a method for demodulating frequency shift signal based on fractal box dimensions theory is proposed in this paper. In view of that the frequency shift signal is FSK signal whose phase is continuous phase and fractal dimension approaches 1, according to the corresponding relationship between the computation process of fractal dimension of frequency shift signal and the derivatives of the signal under different fractal scales, making use of the difference between the derivatives of the upper and lower frequency of the signal to obtain the modulating frequency. Experiment results show that this method is characteristic of accurate computation, easy implementation, good realtimeness, etc., providing a new scheme for analyzing and demodulating railway frequency signal.