ADAPTIVE SERVO GAP DETECTION FOR TIMING BASED SERVO

摘要

DISCLOHSED ARE A METHOD AND A DETECTOR FOR ADAPTIVELY DETECTING SERVO GAPS IN A TIMING BASED SERVO PATTERN PRERECORDED ON A VARIABLE MEDIA.THE TIMING BASED SERVO PATTERN HAS GROUPS OF REPEATED PAIRS OF NON-PARALLEL TRANSITION STRIPES ARRANGED IN BURST, THE BURST SEPARATES BY SERVO GAPS WHOSE LENGTH IS VARIABLE. ASERVO SYSTEM SENSOR SENSE THE TRANSITION STRIPES IN THE LONGITUDINAL DIRECTION OF THE MEDIA. AGROUP INTERVAL DETECTOR COUPLED TO THE SENSOR DETECTS THE TIMING INTERVAL BETWEEN THE SAME SLOPE TRANSITION STRIPES OF TWO SEQUENTIAL GROUPS OF BURST. A DIVIDER DIVIDES THE DETECTED GROUP TIMING INTERVAL BY A PREDETERMINED DIVISOR TO PROVIDE A DIVIDED TIMING INTERVAL GAP DETECTION THRESHOLD .A SEQUENTIAL STRIP INTERVAL DETECTOR COUPLED TO THE SENSOR MEASURES THE TIMING INTERVAL BETWEEN STRIPES, AND A COMPARATOR COMPARES THE DIVIDED TIMING INTERVAL AND THE TIMING INTERVAL, IDENTIFYING A SERVO GAP UPON THE MEASURED TIMING INTERVAL AT LEAST EQUALING THE GAP THRESHOLD. THE DETECTOR RESPONDS TO "VALID" SIGNALS WHICH INDICATE THE VALIDITY OF THE DETECTED GROUP TIMING INTERVAL, REPEATION OPERATION OF THE DIVIDER TO UPDATE THE GAP THRESHOLD , REPEATING OPERATION OF THE COMPARATOR WITH THE UPDATED GAP THRESHOLD TO CONTINUE TO IDENTIFY THE SERVO GAPS.