Sync Stripper and Sync Inserter (HFA1115, HFA1135)


Posted on Apr 22, 2012

In video systems it is frequently necessary to remove the sync pulse from a video signal, while passing the active video information. A familiar application for this is the scrambling of premium channels by cable operators so that they may only be viewed by authorized subscribers. The removal of the sync pulse makes it impossible for the television receiver to lock onto the video signal thus producing a highly distorted picture. Sync strippers are also useful for removing the sync pulse from video signals preceding A/D conversion. After removal of the sync pulse, the active video portion of the signal may be gained up to the full scale input range of the converter for better resolution.



Figure 1 shows a composite video sync stripper composed of an Output Limiting Op Amp (U1) and a Programmable Gain, Output Limiting Buffer (U2). U2 is the video amplifier/driver, and is configured in a gain of 2 in order to provide an overall unity gai




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