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Next is data pre-processing. In order to extract more features from a one-dimensional time-series signal, we adopt the TFA method, where the short-time Fourier transform (STFT) is designed to acquire the time and frequency domain characteristics of signals simultaneously. The STFT of the discrete signal x (n) can be written as this. where g (n) is the window function. Since the time-frequency image is obtained by transforming the signal processed by the STFT sliding window function, the time and frequency domain resolutions are not available at the same time. To avoid the serious distortion, we choose Hann window and set the length of the window function to be 256. Moreover, we set the overlap part of the window function as half length of the window function. |
IEEE/ICACT20230135 Slide.07
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