User Manual

6 To Make Measurements RIGOL
MSO4000D/S4000 User’s Guide
6-7
Note: In FFT mode and when MATH is the active channel, you can also press
HORIZONTAL
SCALE to switch between “Split” and “Full Screen”.
4. Set the Vertical Scale
In the FFT measurement, the unit of the horizontal axis changes from time to
frequency. Use HORIZONTAL
SCALE and HORIZONTAL POSITION
to set the scale and position of the horizontal axis respectively.
The unit of the vertical axis can be dB or Vrms. dB and Vrms use logarithmic
mode and linear mode to display vertical amplitude respectively. If you need to
display the FFT frequency spectrum in a relatively larger dynamic range, dB is
recommended. Press Scale to select the desired unit and the default is Vrms.
Press
and and use to set the vertical position and amplitude of
the FFT frequency spectrum respectively.
5. Antialiasing
Press Anti-Aliasing to enable or disable the antialiasing function. When
enabled, horizontal scale, FTT sample rate and center frequency are doubled.
Tips
 Signals with DC components or deviation would cause error or deviation of
the FFT waveform components. To reduce the DC components, set the
“
Channel Coupling” to “AC”.
 To reduce the random noise and aliasing frequency components of
repetitive or single pulse, set the “
Acquisition Mode” of the oscilloscope
to “Average”.