Tektronix TDS 500C User Manual

Page of 352
Acquiring and Displaying Waveforms
3–54
TDS 500C, TDS 600B, & TDS 700C User Manual
To select Dual Zoom, press ZOOM ➞ Mode (main) ➞ Dual Zoom (side) to
toggle it to ON. (See Figure 3–27.)
Dual zoom displays a second zoomed view of the selected unzoomed waveform.
The second zoomed view is offset in time from the first zoomed view. Also,
zoom must be enabled (side menu set to On or Preview) to see the Dual Zoom
displays.
To set the offset in time of the second zoomed waveform from the first, press
ZOOM ➞ Mode (main) ➞ Dual Zoom Offset (side). Then turn the general
purpose knob or use the keypad to set the offset.
Dual Zoom offset is always positive. The oscilloscope sets the offset as close to
the requested value as possible. An offset request of 0.0 insures that the zoom
boxes are butted up against each other, regardless of the zoom factor.
The horizontal zoom and scale factors determine the minimum offset time
available. Both zoom boxes always enclose equal amounts of time with the
second box always offset from the first by a time equal to one box. Doubling the
zoom factor halves the time enclosed by either box and, therefore, halves the
minimum offset time.
The oscilloscope retains any value input that is less than the minimum time
available as a “request” if you enter that value using the keypad. Increasing the
zoom factor or decreasing the horizontal scale to a setting that allows the
requested value sets offset time to that value. You cannot set offset to less than
the minimum offset time available when using the general purpose knob.
NOTE. To make setting up Dual Zoom easier, turn on Preview in the side menu.
In this dual-window mode, the zoomed display appears in the top graticule,
while the lower graticule shows the two zoomed portions enclosed in two boxes
on the unzoomed waveform. Adjusting offset moves the right box relative to the
left box, which remains stationary. The associated zoomed waveform in the
upper graticule moves to track the offset changes. You can also adjust the
waveform relative to the zoom boxes by selecting the lower graticule and
adjusting the vertical and horizontal control knobs. See 
Using Dual Window
Mode on page 3–52.
Dual Zoom a Waveform
To Set Dual Zoom Offset