Audio and video references – Grass Valley NV8500 Series v.3.5 User Manual
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Inputs and Outputs
Audio and Video References
For NV8500 routers other than the NV8140, the input backplane has 5 modules for a total of
10 LC connectors. The backplane accepts 9 inputs; the 10th connector is not used.
For the NV8140, the input backplane has 9 modules for a total of 18 LC connectors.
The output backplane has 9 modules for a total of 18 LC connectors.
Like the input backplane, the expansion output backplane has 5 modules for a total of 10 LC
connectors. The backplane emits 9 outputs; the 10th connector is not used.
Audio and Video References
The NV8500 provides both AES (async) and video reference connections. Internal audio clocks
can be either set to an external AES reference or generated by the control card from the video
reference. The references are labeled AES REF and VIDEO REF. References for audio are used in
order of priority, as follows:
AES REF 1
AES REF 2
VIDEO REF 1
VIDEO REF 2
(Internal free-running clock)
AES References
The AES reference is used for clock generation, which provides a timing reference for AES sync
signals, and for timing circuits on the control card. On the rear of the router frames are two AES
reference connections. The primary control card and the secondary control card share the AES
reference.
The AES reference connections are redundant and should use the same reference signal. When
both references are connected, if one reference fails, the control card automatically fails over to
the redundant reference.
AES reference connections require a stable audio signal source set at 48
kHz. See
Video References
Located on the rear of the router, four BNC connectors provide video reference input. If a video
reference is present, signals switch at the defined frame rate and line switch points. If a video
reference is not present, the router still performs the switch, but according to an internal refer-
ence. If a video reference is not connected, the control card illuminates its (red) alarm LED. (For
details about LEDs, see
Video reference connections require a stable source of PAL, NTSC, or tri-level sync. The control
card uses these references to perform takes at the proper point in time (according to SMPTE
RP168). See
Redundant and Dual Video References
The same reference can be used for both reference connections or different references can be
applied at the two connectors. If you apply the same reference, the connection is termed redun-
dant. If one reference fails, the control card fails over to the redundant reference.