Sensors & Data Acquisition — question 8 of 10
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This is a diagnostic question about recognizing and confirming aliasing in real spectral data, not designing the anti-alias filter itself.
You're monitoring vibration on a rotating shaft with an accelerometer sampled at 2 kHz, so your Nyquist frequency is 1 kHz. You expect meaningful vibration content up to about 900 Hz from known mechanical modes. During a test, the FFT of your data shows a strong, narrow peak at exactly 300 Hz that doesn't correspond to any known shaft speed, gear mesh frequency, or bearing defect frequency in your system. What's your leading hypothesis, and how would you confirm it on the bench?