FFT Shows No Peaks: 4 Sensor Setup Mistakes That Kill Spectra

#fft #vibrationanalysis #sensorsetup #cbm

You Collected 10 Minutes of Vibration Data and the FFT is Completely Flat

Your sensor is mounted. Your DAQ is running. You've got gigabytes of vibration data streaming in. You fire up your FFT analysis script, expecting to see beautiful bearing fault harmonics at 3.2X shaft speed.

Nothing. A flat line with maybe some low-frequency drift and white noise.

This happens more often than you'd think, and it's almost never the FFT algorithm's fault. I've debugged this exact scenario four times in the past year across different facilities — pumps, fans, conveyor gearboxes. Every single time it came down to one of four sensor setup errors that nobody checks until they've already wasted hours staring at spectrograms.

Here's what actually breaks your frequency spectrum, with the fixes that worked.