User Manual

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6.3 Multiplication and Division
When you select multiplication or division, the Source A and Source B values are multiplied or
divided point-by-point and the result is displayed. Division by a waveform that passes through
zero can result in positive or negative spikes in the graph.
1. Press the Math button to enter the MATH menu.
2. Press the Operation softkey and turn the Universal Knob to select * or / to multiply or divide.
3. Press the Source A and Source B softkeys and turn the Universal Knob to select the two
sources for the math operation. The analog channels and reference waveforms can be used
as sources.
4. The Invert softkey is available to invert the result.
5. Press the Scale softkey and turn the Universal Knob to scale the V/div.
6. Press the Position softkey and turn the Universal Knob to move the result’s vertical position.
6.4 FFT (Fast Fourier Transform)
The FFT operation is used to compute the fast Fourier transform of the analog input channels or
the reference waveforms. The FFT takes the digitized time record of the waveform 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 dBVrms or Vrms (or corresponding current
units) versus frequency. The readout for the horizontal axis changes from time to frequency
(Hertz).
Some uses of the FFT operation are:
• Measure harmonic components and distortion in a system.
• Measure the noise characteristics of DC power.
• Analyze vibration.
• Evaluate the effectiveness of a filter.
To display a FFT waveform
1. Press the Math button to open the MATH menu.
2. Press the Operation softkey and turn the Universal Knob to select FFT. The resulting FFT
waveform is displayed in white.
3. Press the Source softkey and turn the Universal Knob to select the source for the FFT
operation. The analog channels can be used as the source.
4. Press the Window softkey and turn the Universal Knob to select an appropriate window.
Note: Spectral leakage can be decreased when the proper window function is used. The
oscilloscope provides four kinds of FFT window functions which have different characteristics and
are applicable to different waveforms. Please read the table below to make an appropriate
window choice.