Methods for searching for SAM patterns at multiple nominal frequencies
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorRichard M. Ehrlich
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Abstract
Methods are provided for improving servo-demodulation robustness, especially when used with a disk having zone bit recorded servo wedges. A servo address mark (SAM) pattern is searched for, within a servo wedge, at a first nominal frequency useful for searching for the SAM pattern if the servo wedge is within a first zone. The SAM pattern is also searched for, within the same servo wedge, at a second nominal frequency useful for searching for the SAM pattern if the servo wedge is within the second zone. A determination of which one of two zones a head is reading, can then based at least in part on which nominal frequency was used to successfully detect the SAM pattern.
Claims24
A method for use with a disk including zone bit recorded servo wedges, comprising:
- (a) searching for a SAM pattern, within a servo wedge, at a first nominal frequency useful for searching for the SAM pattern if the servo wedge is within a first zone;
- and
- (b) searching for the SAM pattern, within the same servo wedge, at a second nominal frequency useful for searching for the SAM pattern if the servo wedge is within a second zone.
The method of clam 4, wherein:
- step (a) includes, if the SAM pattern is detected at the first nominal frequency, then determining at least one actual servo demodulation value corresponding to a detection of the SAM pattern at the first nominal frequency;
- step (b) includes, if the SAM pattern is detected at the second nominal frequency, then determining at least one actual servo demodulation value corresponding to the detection of the SAM pattern at the second nominal frequency;
- and
- step (c) includes selecting one detection of the SAM pattern based at least in part on the actual servo demodulation values determined at steps (a) and (b), if the SAM pattern is found at both the first nominal frequency and the second nominal frequency in the same servo wedge.
A method for use with a disk including zone bit recorded servo wedges, comprising:
- (a) searching for a SAM pattern, within a servo wedge, at a first nominal frequency useful for searching for the SAM pattern if the servo wedge is within a first zone, and at a second nominal frequency useful for searching for the SAM pattern if the servo wedge is within a second zone;
- (b) for each detection of the SAM pattern in the servo wedge, charactering the detection as a good SAM detection or a bad SAM detection;
- and
- (c) if a detection of the SAM pattern is characterized as a good SAM detection, then performing further servo functions based at least in part on the detection of the SAM pattern this is characterized as the good SAM detection.
A method for improving servo-demodulation robustness, comprising:
- simultaneously searching for a servo address mark (SAM) pattern, within a same servo wedge, using a plurality of different nominal frequencies.
Dependencies are inferred from the claim text.