Reference

Luminance Gain Measurement. The signal is driven along the vertical axis above and below the center box by the luminance signal. The luminance gain is correct when the center dot (clamped black level) is centered in the target box and the positive and negative excursions end at the top and bottom of the graticule. Perfect monochrome signals appear as a thin vertical line. Any deviation or bending off the center line indicates a color variation from the monochrome setup of the display monitor.

Interchannel Timing Measurement. The scale (sequence of dots) between the green and magenta targets provides a way to check interchannel timing (CH-2 to CH-1 and CH-3 to CH-1) or signal delay. If the color difference signal is not coincident with luminance, the transitions between color dots will bend. The amount of this bending represents the relative signal delay between luminance and the color difference signal. The upper half of the display measures the Pb-to-Y timing, while the bottom half measures the Pr-to-Y Timing. If the transition bends in toward the vertical center or black region, the color difference signal is delayed with respect to luminance. If the transition bends out toward white, the color difference signal is leading the luminance signal.

Figure 3-13 shows a signal with proper interchannel timing. In Figure 3-14, the Lightning display shows that the signal has Y-Pb and Y-Pr timing errors.

Pr and Pb Gain Measurement. The horizontal deflection of the top half of the display is an indication of the Pb gain and the lower half indicates the Pr gain. If the color bar signal dots are within the horizontal dimensions of the appropriate graticule targets, the Pb and Pr gains are within 2% of the correct amplitude.

Since the vertical and horizontal dimensions of the graticule target boxes indicate 2% luminance and color difference gain errors, respectively, you can evaluate each color bar for encoding accuracy with these limits.

WFM700 Series Waveform Monitors User Manual

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