DEFECT DETECTION AND COMPENSATION METHODS AND APPARATUS

摘要

DEFECT DETECTION AND COMPENSATION METHODS AND APPARATUS In playback of a video record (e.g., in video disc form) employing a FM carrier recording format, a defect compensation system is provided which substitutes delayed video signals for current video signals when a defect is encountered The current video signals are obtained from the output of the player's pickup-responsive FM detector via appropriate frequency responsive circuitry. To detect the occurrence of a defect, the FM detector output is also supplied to additional frequency responsive circuitry having a wideband response. The wideband circuit output is supplied to a pair of voltage-level comparators. The comparator outputs are added together to form a defect indication signal. Switching between current and delayed video signals is controlled in response to the defect indication signal. Operation in the delayed signal mode is maintained for a short period after defect indication pulse termination by rendering a retriggerable one-shot responsive to the defect indication signal, and combining the output of the one-shot with the defect indication signal to form the switching control signal.