User`s manual

Alcorn McBride Digital Video Machine DVM-7400 User’s Manual Rev 1.5
75
Synchronization
If you intend to use
the DVM for an
application that
requires video sync,
be sure to order your
DVM equipped with
the Professional
Video(/P) or Digital
Video(/D) Option.
One of the most powerful features of the Digital Video Machine is its ability to
synchronize to an external video source. This ability makes the DVM a perfect
solution for the following type of applications:
• Synchronized playback on multiple displays
– Any application that entails
side-by-side displays, edge-blended projectors, or 3D projection require
perfect frame synchronization between multiple video sources. Without it,
each display would be playing a different portion of the video at different
times, ruining the desired effect.
• Tightly Synchronized Shows
– Since the DVM can slave to an external
video clock; it has the ability to keep perfect time with other devices that are
slaved to the video clock as well. Some examples of these devices might be
other video players, audio players, SMPTE Generators, or Show Controllers.
• Broadcast Applications
– For reasons that are beyond the scope of this
manual, broadcasters typically require all of their video equipment to be
slaved to an external sync source.
Configuring the DVM for External Sync
The DVM generates
C-Sync and Sync Out
connector. This
means that if you are
connecting the Sync
Output of one DVM to
the Sync Input of
another, the receiving
DVM needs to be
configured for C-Sync.
The yellow LED
located next to the
sync connectors only
illuminates when a
sync signal is
detected. This
indicates that the
DVM is using that
sync signal to
generate video.
Sync Mode
The Digital Video Machine is designed to accept either of the two most widely used
types of sync; Composite sync and Blackburst sync. Once you determine what type
of sync source you intend to use, you must set the Sync Mode DIP-Switch to the
corresponding type. If you are using Composite sync (typically referred to as C-
Sync), the Sync Mode DIP-switch must be in the DOWN position. Therefore, setting
the DIP-switch to the UP position would configure the DVM for Blackburst sync.
Setting this switch is necessary for the DVM to interpret the sync signal reliably.
75Ω Termination
It is always good practice to terminate every active sync line with 75Ω. This means
that the 75Ω DIP-switch should always be DOWN whenever the DVM is receiving
sync directly from a sync generator, video distribution amplifier, or another DVM. The
only occasion where you would want to disconnect the 75Ω termination is when you
are ‘splitting’ a sync line. An example of this would be daisy-chaining a single sync
line to multiple DVM’s using BNC T-Connectors. In this scenario, you would only want
to terminate the last DVM in the chain.
Video Format
The last important step in configuring a Digital Video Machine to receive external sync
is verifying that the video format of the DVM matches that of the incoming sync signal.
For example, you do not want to feed a PAL sync signal into a DVM configured for
NTSC. If you were to do so, the DVM would reject the sync signal and generate its
own instead. The DVM would indicate this by turning OFF the yellow LED. The
DVM’s video format can be changed at any time using the configuration DIP switches
located on the side of the machine.