Filter
Top Products
Reference
WFM700 Series Waveform Monitors User Manual
3-41
Vector Timing Measurements. In the composite domain, the transitions between
the vector end points display timing differences. Because these timing differ-
ences include the delay in the decoder output filtering, you can usually ignore
them. In the component domain, there is no decoding required. Therefore, the
color bar transitions contain useful timing information. These timing differences
appear as looping or bowing of the transitions. While the Vector display allows
you to visualize interchannel timing errors, use the Lightning display to quantify
the amount of timing error.
The Lightning display is a Tektronix, Inc. proprietary display combining a
vertical luminance axis with horizontal chrominance information. The Lightning
display plots the color difference signals, Pb and Pr, with the luminance (Y)
signal. In the top half of the Lightning display, Pb is plotted against Y, and on
the bottom half, Pr is plotted against inverted Y. The vertical center is the 0 V or
black-clamp point.
Lightning Graticule. The Lightning graticule (see Figure 3--13) has two sets of
small cross-hairs that bisect the green-magenta transitions on a color bar signal.
The calibration of the marks is shown in Table 3--7. The electronic graticule
eliminates the effects of CRT nonlinearity.
You can adjust the vertical and horizontal gain using the Gain menu and the
Sweep menu to normalize signal amplitude and to expand the scale of the
display to better view the small timing graticule cross-hairs.
Table 3- 7: Lightning graticule marks
SD cross-hair timing error calibration
1
HD cross-hair timing error calibration
1
Graticule mark Description Graticule m ark Description
Center Aligned Center Aligned
1
st
mark 20 ns 1
st
mark 2ns
2
nd
mark 40 ns 2
nd
mark 5ns
3
rd
mark 74 ns
(one luma sample time)
3
rd
mark 13.5 ns
(one luma sample time)
4
th
mark 148 ns
(one chroma sample time)
4
th
mark 27 ns
(one chroma sample time)
1
The graticule calibration is only correct if the color bar signal lands in the targets.
Lightning Display
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176 - FAX 781.665.0780 - TestEquipmentDepot.com