A Synce Pulse, or Synchronization Pulse occurs in the time period between video fields or video scan lines. In a 1 V p-p amplitude video signal the sync pulse extends 0.285 V p-p negative of the rest of the composite video signal making its detection electrically simple. Sync pulses enable video equipment to operate in synchronization. For instance, a video monitor uses video sync pulses to synchronize with a video source so that it starts the display of each video field and each horizontal scan line at the same time that the actual picture information becomes available from the source. A loss of sync pulses will cause picture distortion commonly described as “rolling” for loss of vertical synchronization or “tearing” for loss of horizontal synchronization.

Mentioned in:
Video Sync Seperator, Sync Stripper, Sync Generator, 315 series
IRE, defined in terms of video