Reference

Vector Timing Measurements. In the composite domain, the transitions between the vector end points display timing differences. Because these timing differences 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.

Lightning Display 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 calibration1

HD cross-hair timing error calibration1

Graticule mark

Description

Graticule mark

Description

 

 

 

 

Center

Aligned

Center

Aligned

1st mark

20 ns

1st mark

2 ns

2nd mark

40 ns

2nd mark

5 ns

3rd mark

74 ns

3rd mark

13.5 ns

 

(one luma sample time)

 

(one luma sample time)

4th mark

148 ns

4th mark

27 ns

 

(one chroma sample time)

 

(one chroma sample time)

 

 

 

 

1The graticule calibration is only correct if the color bar signal lands in the targets.

WFM700 Series Waveform Monitors User Manual

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