21
Installation
The calibration waveform consists of a four-video-line sequence
within an eight line sequence. It starts with a line which contains
the upper 1/4 of the 10-bit Y channel dynamic range and a Y
channel 100% peak reference level. The next two lines are the
upper or lower 1/8 of the C
B
then C
R
channel 10-bit dynamic
ranges and 100% peak positive or negative reference levels. The
fourth line contains the lower 1/4 of the Y channel 10-bit dynamic
range and a Y black reference level.
NOTE:
This fourth line does not need to be observed unless the MII or
BETA (US versions) are being used in which case the Y black level must
be adjusted.
The four line sequence repeats with no changes in the Y channel
lines but with the opposite end (upper or lower) of the chroma
channels being displayed. See figure 11 for typical example of
calibration display with 100% full field color bar input and last bar
at black level. The waveform presents a magnified view of peak
digital video levels as compared to digital reference levels. The
module video gain controls can be adjusted to make the video
peak levels match the appropriate reference level as closely as
possible.
When adjusting B-Y and R-Y gains, offset errors, lack of waveform
symmetry, and/or A/D converter linearity errors may make it
impossible to make both waveform peaks match the reference
levels at the same time. The method of adjustment previously
mentioned can be used for GBR inputs while observing the
calibration display.
illustrates the 8301A Calibration Waveform.
347301A1.book Page 21 Thursday, November 2, 2000 10:41 AM
