Section 4 - Waveform Mode
VM700A Option 01 (NTSC) & Option 11 (PAL) User Manual
4-11
Cursors
The VM700A provides a set of cursors that enable you to make custom
measurements manually with a high degree of accuracy. You can use the cursors
to:
Measure time duration
Measure frequency
Measure luminance or chrominance amplitudes
Measure rise or fall times
Toggle quickly between any two points in a frame
Primarily, cursors are used to make measurements not automatically made in
Auto mode or Measure mode. They can also be used to verify some of the
automated measurements, should the need arise. The accuracy of the cursors is
limited by the one percent vertical accuracy of the VM700A display. Accuracy
may be improved (at the expense of update speed) if Precision mode is on.
The cursors, which are displayed when the Cursors soft key is selected, are two
vertical bars. The Left cursor is a solid vertical line and the Right cursor is a
dashed vertical line. When both cursors are on the same point, they appear as a
dotted vertical line. The default position for the cursors is the center of the
display.
Each cursor has a pair of horizontal “amplitude reference markers” that extend
from the cursor to the furthest left or right point the cursor touched on the
waveform. The anchor point of each amplitude reference marker is a short
vertical line on the waveform. The amplitude reference markers are cleared and
reset when the Reset Cursors, Center Left, or Center Right soft keys are
selected. Amplitude reference markers are used to establish 0% and 100%
reference levels so that the cursor can be positioned at a specific level (e.g., 50%)
as needed for a measurement.
Selecting the Cursors soft key displays the cursors and the submenu shown in
Figure 4-3. When cursors are on, three additional status lines appear: (1) Sine
pk-pk (mV), freq (MHz), and offset (mV); (2) Time from L to R, and Vertical
Delta; and (3) Frequency (1/T), and % point (% point appears as UNDEFINED
point when cursors are first turned on or when the Reset Cursors soft key is
touched).
The values in the first Cursor status line are measured at the center of the display.
The message Sine wave at middle of screen has frequency
above 1.5 x Subcarrier: not measurable is displayed when no
sine wave is found at the center. This condition occurs when measuring noise
Cursor Appearance
Cursor Status Lines
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