Barco R9001330 Owner's Manual page 73

Random Access Adjustment Mode
Vertical refresh [sync/async] : The way of updating the image
information on the LCD panels. For moving images, the vertical
refresh has to be done on a synchronous way, for still images,
asynchronous vertical refresh is possible.
Vertical sync polarity : [leading] or [trailing]
The vertical refresh can be synchronised with the leading sync edge
or trailing sync edge. Default on [leading].
Toggling to [trailing] is only necessary for special applications where
the trailing edge of the sync signal has to be taken as a reference.
Use the ENTER key to toggle between [leading] or [trailing]
Press EXIT to leave the Edit File Option menu.
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