| 摘要 |
AN ATSC (ADVANCED TELEVISION SYSTEMS COMMITTEE) VSB (VESTIGIAL SIDEBAND) RECEIVER (15) INCLUDES A CARRIER TRACKING LOOP (CTL) (115) FOR PROCESSING A RECEIVED ATSC VSB SIGNAL AND A CTL LOCK DETECTOR (200). THE CTL LOCK DETECTOR INCLUDES AN AVERAGING FILTER (135) FOR AVERAGING THE DOWN-CONVERTED RECEIVED ATSC VSB SIGNAL TO PROVIDE A DC OFFSET,AN ESTIMATOR (130) FOR PROVIDING AN ESTIMATE OF THE DC OFFSET, AND A COMPARATOR (140) FOR PROVIDING A LOCK SIGNAL AS A FUNCTION OF A COMPARISON BETWEEN THE ESTIMATE OF THE DC OFFSET AND THE DC OFFSET, WHEREIN THE LOCK SIGNAL IS REPRESENTATIVE OF EITHER A LOCKED CONDITION OR AN UNLOCKED CONDITION OF THE CTL.
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