Tektronix TLS 216 User Manual page 257

Zooming on Waveforms
To Understand Zoom
Using with Groups
Interpolation and Zoom
TLS 216 User Manual
The TLS 216 Logic Scope can expand or compress (zoom in or out) on a
waveform group without changing the acquisition parameters (sample rate,
record length, and so on). This article describes how to use zoom and how it
interacts with the selected waveform group. It also describes how interpolation
can affect zoom.
To help you use zoom effectively, consider how it operates on groups and how it
is affected by interpolation.
When zooming vertically, the logic scope expands or contracts the selected group
only. You must set the group display mode to Analog in the Group Menu to see
the selected group zoomed on screen. If in BusForm or Timing Diagram display
mode, the vertical zoom factor will change if adjusted, but the group amplitude
will not change size on screen until you switch to Analog mode.
When zooming horizontally, zoom expands either the selected group, all live
groups, or all live and reference groups depending on the setting for Horizontal
Lock in the Zoom menu. Zoom expands on screen for all three group display
modes.
When zooming horizontally or vertically, zoom expands or contracts the group
by the zoom factor in 1X, 2X, and 5X steps.
When you zoom on a group, you expand a portion of it. If the expansion requires
the logic scope to show more points for that portion than it has acquired, it
interpolates.
The method the logic scope uses to interpolate, linear or sin(x)/x, can affect the
way zoom displays your waveform. If you selected sin(x)/x (the default), it may
introduce some overshoot or undershoot to the waveform edges. If that happens,
change the interpolation method to linear, following the instructions on
page 3–177.
To read about the two interpolation methods, see Interpolation on page 2–20. To
differentiate between the real and interpolated samples, set the display style to
Intensified Samples. (See To Choose a Display Style on page 3–38.)
3–175