Matrox 4Sight User Manual page 201

Trigger
A signal that allows image acquisition to be synchronized to
external events. If supported, a digitizer can operate in one
of two modes upon receiving a trigger:
Asynchronous reset mode: If your digitizer supports and
uses this mode, the camera is reset to begin a new frame
when the trigger signal is received.
Next valid frame/field mode: If your digitizer supports and
uses this mode, the digitizer will grab the next valid frame
or field.
Vertical sync
The part of a video signal that indicates the end of a frame
(or field) and the start of a new one.
See also horizontal sync.
Vpp
Voltage peak to peak. The signal amplitude measured
between the maximum positive and negative voltage peak
excursions of a signal.
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