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Purpose
Method
Burst (TV formats only)
Description
Test
Method
882 Video Test Instrument User Guide (Rev A.35)
The light output of most picture tubes varies slightly when measured across the CRT face.
This test can be used to verify that the light output variation is within your specification
limits.
Select the inverted version and perform the Brightness Control Adjustment test on the
center box. Then, center the light meter probe in each of the corner squares and note the
reading you get for each square. The deviation between each of the corner readings and
the center reading should be within your specification limits.
The left side starts with reference white (+100 IRE) and black (+7.5 IRE) levels. This is
followed by six bursts of sine waves. Each burst is at a different frequency, forming vertical
lines of various widths. The frequencies, going from left to right, are 0.5, 1, 2, 3, 3.58, and
4.43 MHz.
Frequency response
When viewed on a TV screen, the peak intensities of all of the bursts should match the
white reference level. The darkest portions between the peaks should match the black
reference level.
The image can also be used with a TV waveform analyzer to check the frequency
response of a video system. One scan line of the image, as it would appear on a
waveform analyzer, is shown at the top of the next page . High frequency roll-off (loss)
would show up as a decrease in the peak-to-peak swings on the right side of the
waveform. Low frequency roll-off would show up as a decrease in the peak-to-peak
swings on the left side of the waveform.
883
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