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Reference
Zoom
At times, you may want to expand or compress a waveform on the display
without changing the acquisition parameters. You can do that with the zoom
feature.
When you zoom in on a waveform on the display, you expand a portion of the
waveform. The digitizing oscilloscope may need to show more points for that
portion than it has acquired. If it needs to do this, it interpolates. The instru-
ment can interpolate in either of two ways:
linear
or
sin(x)/x
. (The interpolation
methods are described on page 2-21.)
When you zoom, the display redraws the waveforms using the interpolation
method you selected in the Display menu (linear interpolation or sin(x)/x). If
you selected sin(x)/x (the default), it may introduce some overshoot or under-
shoot to the waveform edges. If that happens, change the interpolation meth-
od to linear, following the instructions on page 3-163.
To differentiate between the real and interpolated samples, set the display
style to Intensified Samples.
When you turn on the zoom feature, the vertical and horizontal scale and
vertical position knobs now control the displayed size and position of wave-
forms, allowing them to be expanded and repositioned on screen. They cease
to affect waveform acquisition, but you can alter acquisition by using the
corresponding menu items. Zoom mode does not change the way horizontal
position operates.
To use zoom, do the following steps:
1. Press ZOOM ➞ ON (side). The ZOOM front-panel button should light up.
2. Choose which waveforms to zoom by repeatedly pressing Horizontal
Lock (side).
None — only the waveform currently selected can be magnified and
positioned horizontally (Figure 3-86).
Live — all channels (including AUX channels for the TDS 524A &
TDS 620A) can be magnified and positioned horizontally at the same
time. (Waveforms displayed from an input channel are live; math and
reference waveforms are not live.)
All — all waveforms displayed (channels, math, and/or reference)
can be magnified and positioned horizontally at the same time.
Zoom and
Interpolation
Operation