VSC 150 • Installation and Operation
VSC 150 • Installation and Operation
Installation and Operation, cont’d
termination adapter to the other “input” connector, or
by setting the 75 Ohm DIP switch to On (75 ohms).
The Burst Lock LED lights green to indicate that the
VSC 150 is receiving an acceptable genlock (black
burst) sync signal via the Genlock In connector.
4
.
Connect oscilloscope (“scope”) probe A to the Genlock
Out connector. This will provide the scope’s reference
signal. In order to avoid altering the genlock signal,
use the cabling configuration that will be used in the
installation. Either connect the genlock signal cable
from the scope to the next device in the system to be
timed, or provide 75 ohm termination at the scope’s
genlock output.
5
.
Connect scope probe B to the VSC 150’s composite video
output connector. Ensure that the rear panel PAL Out
DIP switch is set for the desired standard (NTSC/PAL).
6
.
Using the instructions for the scope you are using, set
the scope to view the signals’ horizontal phases.
Adjust the VSC 150’s Horz Phase control until there is
no (0º) difference between the composite video
output’s horizontal sync phase and the genlock signal’s
horizontal phase. See “Oscillocope displays”.
7
.
Set the scope to view the subcarrier signals. Adjust
the VSC 150’s Sub Phase control until there is a zero
phase difference between the genlock signal and the
NTSC/PAL output. The Burst Lock LED should light.
If the Burst Lock LED does not light at this point,
either adjust the horizontal or subcarrier phases
further, or use a different genlock source.
The color subcarrier adjustment range is ±90° from
0° for a total adjustment range of 180°.
8
.
View the horizontal phases again. If the phase
difference is not zero, repeat steps 6 and 7 until the
settings do not change.
If the Burst Lock LED does not light at all when
genlock is active and the horizontal and subcarrier
phases have been adjusted to match the genlock
signal, do not continue with this procedure. A
different, more stable or time-base-corrected sync
signal must be used for the genlock timing source.
9
.
Once the settings are stable and the Burst Lock LED
lights, disconnect the oscilloscope, and reconnect the
genlock cables and terminator to the proper devices in
the system.
2-15
If the genlock connectors are used only for vertical interval
switching, no horizontal or subcarrier phase adjustments
are required, and the Burst Lock LED does not light.
Genlock setup
Genlock differs from simple vertical interval switching in
that an external device (a black burst generator) generates a
reference sync signal for the system, and every device that
uses that signal has its output signal’s horizontal and
subcarrier phases adjusted to exactly match that of the
generator to allow precise timing and full synchronization.
Genlocked systems produce cleaner switches between
inputs than do those without this type of synchronization.
An oscilloscope is required for genlock setup, and a vector-
scope is recommended. Waveform monitors of types other
than a vectorscope may give the appearance that timing is
adjusted correctly when it is 180 degrees out of phase,
which will result in incorrect colors or picture artifacts.
All equipment in the system must be powered up
and turned on for at least 15 to 20 minutes before
genlock setup adjustments can be made and before
the equipment is used in a genlocked application.
To synchronize the VSC 150’s video output with a genlock
signal, follow these steps:
1
.
Power up and turn on all the devices that will use the
genlock signal. The devices must be on for at least 15
to 20 minutes before proceeding with any adjustments.
To Scope Probe A
and Termination
To Scope Probe B
Computer Video
Signal In
50/60 Hz
100-240 V 0.3A
S-VIDEO
R-Y/B-Y/Y
RGB
R/R-Y
H
V
S
G/Y
B/B-Y
RS-232
OUT
IN
GENLOCK
S-VIDEO
P
AL OUT
75 OHM
VIDEO
MAC
VGA
I
N
P
U
T
S
O
U
T
P
U
T
S
Timing Source
OUT
Cable connections for genlock setup
2
.
Connect the active timing source signal to the
Genlock In connector on the rear panel.
3
.
Connect the active computer video input signal to the
appropriate input as explained in step 2 of the Cabling
section on page 2-9. Ensure that the input is properly
terminated either by connecting a local monitor or a
2-14