Checking Chroma/Luma Delay (Lightning Display)
Checking Chro
ma/Luma Delay (Lightning Display)
The Lightnin
g display can be use d for interchannel timing measurements. If the
color-difference signal is not coincident with luma, the transitions between the
color dots will deviate from the center mark of a delay scale. The amount deviated
represents the relative signal delay between luma and the color-difference signal.
1. Connect a signal c ontaining color bar information to an input on the rear panel.
2. Select a tile to view the Lightning Display, then press and hold the VECTOR
button.
3. In the Vector pop-up menu, select Lightning for the Display Type.
4. Set Bar T
argets to match your input signal.
5. Select Center Waveform and press the SEL button to center the waveform.
6. Press the VECT button to close the pop-up menu.
7. Determine where transitions intersect the delay scales and derive the timing
error in nanoseconds, as deflected from the center mark, using the following
guidelines. (See Figure 58.)
The center mark of the nine marks spanning each green-magenta transition
is the zero error point.
Alignment to a mark toward black means the color-difference signal lags
with respect to luma.
Alignment to a mark toward white means the color-difference signal leads
the luma signal.
The upper half of the d isplay measures the Pb to Y timing; the bottom
half measures the Pr to Y timing.
WFM8200 and WFM8300 Waveform Monitors 117
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