Tektronix TDS5054, Руководство пользователя

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Acquiring Waveforms
TDS5000 Series User Manual
3- 15
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 constant
number of divisions of signal after the scale factor is applied to the resulting
difference.
The vertical scale and position controls have the following affects on the vertical
acquisition window and the displayed waveform:
H
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. Figure 3--3 on page 3--16 shows two vertical
acquisition windows that contain the entire waveform, but only one window
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
3--3a and b 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 not affect amplitude measurements on that math waveform.
H
The vertical position adjusts the display of the graticule relative to the
vertical acquisition window (position is a display control). Figure 3--3b
shows how vertical position moves the waveform graticule vertically in the
acquisition window to place the acquired waveform in the graticule display.
That is all position does; it does not determine what data is acquired as do
vertical scale and offset.