Sync Separation

1
Sync Separation

• Composite signal is applied to sync takeoff.
• STEPS 1. Strip sync pulses from video signal
  with a clipper stage. 2. Amplify horizontal and
  vertical sync pulses. (polarity) 3. Separate with
  an integrator and differentiator. 4. Direct
  horizontal and vertical sync pulses to their
  respective deflection oscillators or sweep
  generators.
• Note this process is beam synchronization not
  chroma synchronization.

2
Noise and Sync Separation

• Impulse noise can masquerade as sync pulses.
• What might be some of the symptoms with the
  presence of noise at the receiver?
• REMEDIES 1. Good antenna system. (source)
• 2. Good S/N at RX
• 3. Noise reduction
  circuits.
• Noise cancellation circuit is most common.

3
Vertical Sync Pulse

• Vertical sync pulse is developed at the 6 wide
  pulses within vertical blanking. (note the
  difference in duty cycle to the pre-equalizing
  pulses)
• Requires an integrator with a long time constant
  Sometimes multiple stages.
• This group of integrated pulse will appear as a
  single sharp spiked pulse on an oscilliscope.

4
Horizontal Sync Pulse

• Stripping action provides passage of horizontal
  sync pulses from horizontal line deflection.
• The horizontal pulse from within vertical
  blanking require shaping of the serrations and
  rejection of vertical sync pulses.
• Implement a differentiator with a short time
  constant.