Oscilloscope Reference Vertical Acquisition Window considerations
The offset control subtracts a constant DC level from the input signal before the vertical scale factor is
applied, and the vertical position control adds a c onstant n umber of divisions of signal after the scale factor
is applied to t
he resulting difference.
The vertical scale and position controls have the following affects on the vertical acquisition window
and the displ
ayed waveform:
The vertical volts per division you set determines the vertical size of the acquisition window, allowing
you to scale
it to contain all of a waveform amplitude or only part. Figures A and B below show two
vertical acquisition windows that contain the entire waveform, but only the window in Figure B contains
the entire waveform in the graticule on screen.
NOTE. Amplitude-related automatic measurements (for example, peak-to-peak and RMS) will be accurate
for vertical windows like those shown in Figures A and B below because neither waveform is clipped (that
is, both waveforms are acquired). But if signal amplitude were to extend outside the vertical acquisition
window,
the data acquired is clipped. Clipped data causes inaccurate results if used in amplitude-related
automatic measurements. Clipping also causes inaccurate amplitude values in waveforms that are stored
or exported for use in other programs.
If the scale of a math waveform is changed so that the math waveform is clipped, it will affect the
amplitude measurements on that math waveform as follows:
The vertical position adjusts the display of the graticule relative to the vertical acquisition window
(position is a display control). Figure B shows how vertical position moves the waveform graticule
vertically in the a cquisition window to place the acquired waveform in the graticule d isplay. That is all
position does; it does not determine what data is acquired as do vertical scale and offset.
Figure A
Figure B
682 DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series
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