Vertical synchronization pulse

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In television, a vertical synchronization pulse is sent whenever the television set should start scanning a new image from the top of the screen.

The format of such a signal consists in:

  • pre-equalizing pulses (6 to start scanning odd lines, 5 to start scanning even lines)
  • long-sync pulses (5 pulses)
  • post-equalizing pulses (5 to start scanning odd lines, 4 to start scanning even lines)

Each pre- or post- equalizing pulse consists in a short (by half) scan line of black signal: 2µs at 0V, followed by 30µs at 0.3V.

Each long sync pulse consists in an equalizing pulse with timings inverted: 30µs at 0V, followed by 2µs at 0.3V.