ROBUST DETECTION OF DATA MODULATED INTO A TIMING BASED SERVO

摘要

A DETECTOR AND METHOD FOR DETECTING DATA MODULATED INTO A TIMING BASED SERVO PATTERN PRERECORDED ON A MEDIA, COMPRISING SHIFTS OF PAIRS OF NON-PARALLEL TRANSITION STRIPES ARRANGED IN A FRAME TWO BURSTS. TIMING INTERVALS BETWEEN SEQUENTIAL TRANSITION STRIPES ARE DETECTED. INTERVAL COMPARISON LOGIC COMPARES SELECTED TIMING INTERVALS AND INDICATES WHETHER THE COMPARED INTERVALS REPRESENT A "0" OR A "1". FIRST AND SECOND COUNTERS RESPECTIVELY INCREMENT THE NUMBER OF THE COMPARED INTERVAL REPRESENTING A "0" AND REPRESENTING A "1" IN EACH FRAME. BIT COMPARISONLOGIC COMPARES, FOR EACH FRAME, THE INCREMENTED NUMBERS REPRESENTING A "0" AND A "1" TO A PREDETERMINED CRITERIA AND, UPON ONE OF THE NUMBER MEETING THE CRITERIA, IDENTIFIES THE CORRESPONDING "0" OR "1" AS THE BIT VALUE FOR THE FRAME. THE BITS ARE DATA COMPRISING LONGTUDINAL POSITION WORDS ARRANGED IN A LINEAR SEQUENCE. SEQUENCE LOGIC CALCULATES THE NEXT SEQUENTIAL POSITION WORD FROM AN IMMEDIATELY PRECEDING WORD AND DETERMINES WHETHER THE DETECTED WORD IS IN THE LINEAR SEQUENCE AS A VALIDITY CHECK, AND PROVIDED THE CALCULATED WORD AS THE OUTPUT.THUS, THE CORRECT POSITION WORD IS PROVIDED AT THE OUTPUT EVEN IF THE DETECTED WORD IS INVALID.FIGURE 6