RIGOL MSO/DS2000A Series - Manual (Page 69)

Chapter 3 To Set the Horizontal System RIGOL
MSO2000A/DS2000A User’s Guide 3-3
The Waveform after Enlargement:
The waveform in the lower part of the screen is the horizontally expanded waveform.
Compared to the main time base, the delayed time base has increased the waveform
resolution (as shown in the figure above).
Note: The delayed time base should be less than or equal to the main time base and
can be modified by rotating HORIZONTAL SCALE.
Tip
You can also press down HORIZONTAL SCALE (delayed sweep shortcut key)
to directly switch to delayed sweep mode.