30 September 1988
Learning Event 3:
DESCRIBE THE PROCEDURES USED, IN SEQUENCE, TO TIME A SYSTEM IN THE SC/H
The following steps must be made in sequence to ensure the correct
timing and SC/H phase of all sources (fig 2-3).
a. Adjust the color bar delay DA until the timing of the half amplitude
(50 percent) point of the color bar horizontal sync leading edges match the
timing of the camera sync. A timing match within 10 ns is desirable.
b. Camera 1 subcarrier phase needs to be adjusted to match its burst
phase to the color bar burst phase.
c. The switcher, sync, and blanking pulse delay DAs must be adjusted
until the switcher color background sync 50 percent point and blanking are
in time with the sync and blanking of Camera 1's output.
d. Switcher color timing (internal color black and background)
matched to Camera 1 with the switcher subcarrier phase control.
e. The character generator video delay DA should be adjusted to match
the character generator and Camera 1 horizontal sync leading edges.
f. Adjust the internal subcarrier phase to color time the character
g. The key delay will be adjusted to center the character generator's
fill video within the hole produced by the key signal.
h. Finally, adjust the VCR time base corrector H and SC phase controls
to match each VCR to Camera 1 at the switcher.
This procedure will result in all sources being SC/H phase correct,
only if the color bar video signal is SC/H phase correct. If an SC/H-phase
meter is available, the SC/H phase of all sources can be verified.
approach to system design is usually the least expensive but does have
serious deficiencies. We are distributing sync and subcarrier to equipment
through many different paths. This will make establishing and maintaining
SC/H phase very difficult.
With the many variables in this system, SC/H
phase may drift with time and temperature. Additional source equipment may
be difficult to integrate in the future, and could require major system