Nevion FRS-3G-DUAL - Manual (Page 22)

FRS-3G-DUAL Rev. B
nevion.com | 22
If sync input reappears
Given that a stable SDI input exists: If the sync reference reappears the delay logic will
change back to frame sync mode. Hence the internal clock will be locked to the sync signal
and the delay will change again.
NOTE: This will result in a frame roll as the delay changes.
If both signals disappears
The picture will first freeze for Hold time and then go to one of the internal video generators
(depending on the module’s configuration). The output is now referenced to the local clock
source. This clock will however be kept within 1 ppm of the last sync source seen by the
module.
4.2.2 Frame delay mode
In this mode a sync signal is not present. The phase delay will be set relative to the SDI-
input. In effect this will create a delay line with length equal to the sum of the phase delay
and the additional frame delay, and the output frequency will be locked to the input
frequence.
Here’s what happens when an external error event occurs:
If video signal disappears
The picture will first freeze for Hold time and then go to one of the internal video generators
(depending on the module’s configuration). The output is now referenced to the local clock
source. This clock will however be kept within 1 ppm of the last video input seen by the
module.
If video signal reappears
If the input video signal reappears, the video will reappear on the output Lock time after the
input has stabilized. The delay will be set to the same as before input was lost.
NOTE: This may cause a frame roll.
If a sync input appears
Given that a stable SDI input exists: If a sync signal appears the delay mode will change to
frame sync mode, see Chapter 4.2.1. Hence the internal clock will be locked to the sync
signal and the delay will change.
NOTE: This will result in a frame roll as the delay changes.