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Background: I'm fairly new to signal processing and sensors, etc. I'm working on my thesis, which involves the use of an MEMS acceleration sensor as a vibration measuring device (for rotating machinery). I managed to extract the data from the sensor and save it to my computer. Now, I'm doing post-processing on the data with python. Basically I'm getting accelerations in X, Y ,Z axis and the time (milli seconds).

Problem: the signal is noisy and I'm getting strange results when I perform FFT to it.

I already did detrend (to remove the huge spike at 0 Hz) and used a window function (on the detrended data) to get a cleaner Fourier Transformation but still I'm not sure if what I'm getting is normal.

This is data I get from the sensor. Blue: original data, Orange: after detrend, Green: after applying the window function. I applied the window function to all 3 but only showed it on the X Above is data I get from the sensor. Blue: original data, Orange: after detrend, Green: after applying the window function. I applied the window function to all 3 but only showed it on the X

Here is the FFT of the data, with only unto 4 Hz on the frequency axis. Blue: FFT on detrended signal, Orange: FFT on the windowed signal Above is the FFT of the data, with only unto 4 Hz on the frequency axis. Blue: FFT on detrended signal, Orange: FFT on the windowed signal

FFT of same data but full frequency axis FFT of same data but full frequency axis

The measurements were taken while the sensor was not moving with a sampling rate of 1 kHz. Also, using the sensor's low pass filter of 184Hz.

Am I on the right path? Are these results to be expected? Or is there something wrong with my work?

I hope you guys can help me. Thank you in advance.

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  • $\begingroup$ all of those questions should be directed to your supervisor. If he can not answer it, you should consider replacing him. $\endgroup$ Feb 3, 2020 at 14:45
  • $\begingroup$ @GideonGenadiKogan He gave me some hints as of what to do but it looks like he wants to see better results. $\endgroup$
    – Ra3
    Feb 3, 2020 at 15:31

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