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User Manual
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➢ Measure harmonic components and distortion in the system
➢ Measure the characteristics of the noise in DC power
➢ Analyze vibration
To display FFT waveform:
1. Press the [Math] button on the front panel to open the MATH function menu.
2. Press the Operation softkey and then turn the Multifunctional Knob to select FFT. The resulting math waveform is
displayed on the screen and labeled with “M”.
3. Press the Source softkey, and then turn the Multifunctional Knob to select the source to do FFT operation. Analog channels
(CH1~CH2) can be used as the source.
4. Press Center softkey and then turn the Multifunctional Knob to adjust the frequency of the frequency domain waveform
corresponding to the horizontal center of the screen.
5. Press Span softkey and then turn the Multifunctional Knob to adjust the the horizontal scale of the frequency domain
waveform.
6. Press the Vertical Units softkey to select the unit of vertical axis. The units of the vertical axis can be dB or Vrms which
use a logarithmic scale or a linear scale to display vertical amplitude respectively.
7. Press the Scale softkey to select the vertical scale.
8. Press the Window softkey, and then turn the Multifunctional Knob to select an appropriate window.
Spectral leakage can be considerably decreased when a window function is used. The series of scope provides six kinds of FFT
window functions which have different characteristics and are applicable to measure different waveform. You need to select
the window function according to different waveform and their characteristics. Please read the table below carefully to make
an appropriate option according to the input signal.
Window
Measurement
Characteristics
Rectangular
Pulse or Transient Waveform
Special-purpose window applicable to discontinuous waveform.
This is actually the same as no windows.
Hanning
Periodic Waveform
Better frequency, poorer amplitude accuracy than Flattop
Hamming
Transient or short pulse
A litter bit better frequency resolution than Hanning.
Blackman
Single frequency signal, search
for higher order harmonics.
The best amplitude resolution; the poorest frequency resolution
Bartlett
Narrow band signal with
stronger
Better frequency resolution.
Flattop
Periodic Waveform
Better amplitude, poorer frequency accuracy than Hanning
9. Press the Show-Only softkey to select to display FFT operation results only and not display the source channel.
Note:
1. Signals with DC components or deviation would cause an error or deviation of the FFT waveform components. To reduce
the DC components, set the Channel Coupling to AC.
2. To reduce the random noise and aliasing frequency components of repetitive or single pulse, set the Acquisition of the
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