Dynamic magnetic information storage or retrieval – General processing of a digital signal – Inter-record gap processing
Reexamination Certificate
2010-07-30
2011-11-01
Tzeng, Fred (Department: 2627)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Inter-record gap processing
Reexamination Certificate
active
08049982
ABSTRACT:
Methods and apparatus are provided for measuring servo address mark distance in a read channel using selective fine phase estimates. A distance between servo address marks (SAMs) in servo data of a magnetic recording media can be computed by obtaining a count of a number of time intervals between SAM patterns; obtaining a plurality of fractional phase estimates; selecting at least one of the plurality of fractional phase estimates as a selected fractional phase estimate based on a selection criteria; and combining the count and the selected fractional phase estimate to compute the distance. The fractional phase estimates can include a first fractional phase estimate having a lower resolution and higher accuracy in the presence of frequency errors relative to a second fractional phase estimate and wherein the second fractional phase estimate has more resolution and lower accuracy in the presence of the frequency errors relative to the first fractional phase estimate. The selection criteria can comprise a frequency error threshold.
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Annampedu Viswanath
Grundvig Jeffrey P.
Zhang Xun
LSI Corporation
Ryan & Mason & Lewis, LLP
Tzeng Fred
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