The demodulation algorithm of track frequency shift signal based on windowed interpolation FFT

The track frequency shift signal is closely related to the safe operation of railway locomotives. This paper presents a real - time modified FFT algorithm for the demodulation of rail track frequency shift signal, which can solve the low frequency resolution and serious spectrum leakage in traditional FFT algorithm. Firstly, The sampling frequency is determined by bandpass sampling. Then, FFT algorithm with Manning window is designed. At the same time, polynomial approximation method is used to estimate the frequency and amplitude of the signal by using the maximum amplitude of two spectrum lines near the detection frequency, which corrects the spectrum leakage phenomenon when calculating the frequency shift signal by FFT. Finally, the simulation is carried out on MATLAB, and the experiment is carried out with DSP. The results show that the improved FFT algorithm can improve the accuracy and real-time of track frequency shift signal detection.