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8.7 FFT Operation
The source of the FFT math functions can be analog input channels or a lower math function.
FFT is used to compute the fast Fourier transform using analog input channels. FFT takes the digitized
time record of the specified source and transforms it to the frequency domain. When the FFT function is
selected, the FFT spectrum is plotted on the oscilloscope display as magnitude in dBV versus frequency.
The readout for the horizontal axis changes from time to frequency (Hertz) and the vertical readout
changes from V to dB.
Use the FFT function to: find crosstalk problems, to find distortion problems in analog waveforms caused
by amplifier non-linearity, measure harmonic components and distortion in the device under test, measure
the characteristics of the noise in DC power, analyze vibration, or for adjusting analog filters.
Display FFT Waveform
To display a FFT waveform:
1. Press the
and then the
2. Press the
to select Operator.
3. Use the
Universal Knob
•
The resulting math waveform is displayed in white and labeled as "M".
4. Press the
softkey to toggle the source between CH1 and CH2.
5. Press the
softkey to enter the Config menu.
•
Press the
– A dropdown menu containing the available options will appear.
button to enter the Math menu.
to navigate the available option and select FFT .
Figure 8.2 Config Menu
softkey to select Window.
Math
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