Grass Valley MRC v.1.2 - Manual (Page 156)

146
Tutorials
Video Fields and Frames
router’s externally supplied reference signal(s) and the appropriate switch point (for SD or HD)
to determine when the switch occurs and then initiates the switch.
The signals being switched must be (vertically) timed to its reference signal. In other words,
both the reference signal and the signal being switched must have matching vertical timing.
Video reference are received through two connectors on the router frame labeled ‘Video Ref’ or
‘Video Ref 1 and ‘Video Ref 2’. When both video reference connections use the same type of
signal, we call it “redundant” reference. When the reference connectors use two different
signals, we call it “dual” reference.
(See Redundant and Dual Video References on page 149.)
For details on video reference connections, see the router User’s Guide.
SMPTE Standards for Switch Point
SMPTE standards define the switch point. For NVISION series routers, the following signal types
may be connected to the video reference connections on the router:
Tri-level signals are nominally 600 mV pp when terminated in 75 W. The router will switch prop-
erly if tri-level is double terminated, as well. The router will not work when a tri-level input is not
terminated.
External References and Switch Point Configurations
The following are possible sets of external references and switch point configurations:
• NTSC Reference, Software configures HD switch for 1080i
SD 525/59.94 will switch correctly.
HD 1080i/59.94 will switch correctly.
HD 720p/59.94 will switch, but not at the correct time.
HD 1080p/59.94 will switch, but not at the correct time.
All other standards will switch, but not switch at the correct time.
• NTSC Reference, Software configures HD switch for 1080p
SD 525/59.94 will switch correctly.
HD 1080p/59.94 will switch correctly.
HD 1080i/59.94 will switch, but not at the correct time.
HD 720p/59.94 will switch, but not at the correct time.
All other standards will switch, but not at the correct time.
3. Actually, 59.94 and 29.97 frames per second.
NTSC
PAL
1080i/59.94 Tri-level
1080p/59.94 Tri-level
720p/59.94 Tri-level
1080i/60 Tri-level
1080p/60 Tri-level
720p/60 Tri-level
1080i/50 Tri-level
1080p/50 Tri-level
720p/50 Tri-level
1080p/24 Tri-level
1080p/23.97 Tri-level