How to Use the Instrument
Description and Applications of the Test Patterns
4
4-63
VCR 2
Figure 4-94. VCR 2
VCR 2 is a combined test pattern and is divided into
the following four horizontal bars:
•
Horizontal 100% white bar (100 IRE) covering 1/6
field for exact level adjustment.
•
A bar covering 1/3 field starting with a reference
bar followed by six vertical frequency bursts. For
details, see ‘Multiburst’ pattern earlier in this
chapter. This part is used to align the high-pass
filter for a maximum resolution in the VCR
bandwidth.
•
The next part of the pattern contains eight steps of
decreasing linear saturation steps of the R-Y
signal.
For 625 line systems U = 0 and V decreases from
0.44 to 0.
For 525 line systems Q = 0 and I decreases from
0.45 to 0.
This part is used to check the chroma amplifier
linearity and color AGC circuitry. For example, if
the chroma writing current is too high, color will
be visible in the last bar where no color should be
seen normally.
•
The bottom section consists of a black horizontal
bar with a white square moving smoothly from left
to right to check moving pictures or slow motion
function on video recorders. The speed of the
moving bar is 4.7 s for one cycle in 625 line
systems and 4.0 s in 525 line systems.
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