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FFT Operation
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.
FFT operation can facilitate the following works:
Measure harmonic components and distortion in the device under test
Measure the characteristics of the noise in DC power
Analyze vibration
To display a FFT waveform:
1. Press the Math button on the front panel to open the MATH function menu.
2. Press the Operator softkey and then turn the Universal Knob to select FFT. The
resulting math waveform is displayed in white and labeled with “M”.
Figure 66 FFT Menu
3. Press the Source softkey, and then turn the Universal Knob to select the source
to do FFT operation. Analog channels can be used as the source.
4. Press the Config softkey to enter CONFIG menu.
Figure 67 FFT CONFIG Menu
Press the Maximum points softkey, and then turn the Universal Knob to
select the Maximum points.
Press the Window softkey, and then turn the Universal Knob to select an
appropriate window.
Spectral leakage can be considerably decreased when a window function
is used. The oscilloscope provides five windows (Rectangle, Blackman,
Hanning, Hamming and Flattop) which have different characteristics and
are applicable to measure different waveforms. You need to select the
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