DATA source: Bearing vibration data FEMTO IEEE PHM 2012 challenge.
- Sample rate: 25.6 kHz
- Sample period: 0.1 Seconds (2560 points)
- Motor runs at 1800 rpm
- Low pass butter filter with fc=1000Hz
- Apply hann window
- Apply FFT (np.fft.fft)
The dominant frequency is at ~60Hz which is incorrect it is supposed to be nearer to 30Hz since the motor is ran at 1800RPM.(Correct me if im wrong on this.) What went wrong? Please find the code below.
Fs = 25600 # Hz sampling_period = 0.1 N = int(Fs * sampling_period) fc = 1000 # Cut-off frequency of the filter w = fc / (Fs / 2) # Normalize the frequency b, a = signal.butter(10, w) filter_out = signal.filtfilt(b, a, bearing1_1["horiz_acc"]) f = np.fft.fftfreq(int(N), 1/Fs) window = np.hanning(int(N)) X = 1/N * np.abs(np.fft.fft(filter_out * window)) * 2 # Multiply by 2 for hann window power correction?