Due to unavoidable timing and slope errors in the leading and trailing edges of invert pulses utilized in encoding and decoding of the television signal by inversion of the picture signal portion relative to the synchronizing signal portion, transients are generated. A clamping circuit clamps the television...http://www.google.com.tw/patents/US4022972?utm_source=gb-gplus-share專利 US4022972 - Transient suppression and grey level coincidence in a subscription television system
