I have a vibration signal (25.6 kHz) which has been through the following filters:
1: highpass (2000 Hz) -> (I'm not interesten in the harmonics of the system. I then perform spectral kurtosis to find the optimal bandpass bandwidth.)
2: Bandpass (8750 Hz,9250 Hz) ->
3: Rectification (abs(xi)^2) ->
4.Lowpass (2000 Hz)
The fft of the final signal looks like this:
The Bandpass filter bandwidth and center frequency was selected based on the kurtogram of signal after initial lowpass.
I am no expert in signal processing- does the FFT look "correct"? It seems odd that the amplitudes rarely go below 0.05...
Updates
The original signal (25.6 kHz):
Zoomed in in original signal (25.6 kHz):
FFT of original signal (before step 1)
Objective of project:
- To look for any fault development in the early stages of a gearbox fault on a wind turbine. I have signal data 412 days, in the form of 412 10-second intervals.
- Want to extract features from time and freq. domain and cluster the 412 intervals, to see if there is a pattern.
1:
cut off anything above 2000 Hz, then in2:
cut off anything below 8750 Hz? That very much sounds like a design mistake. If your low-pass filters are good, you don't have any signal after that. $\endgroup$