Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data in specific format
Patent
1997-01-28
1999-12-21
Kim, W. Chris
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data in specific format
360 7708, 360 49, 360 40, 360 53, G11B 509, G11B 5596
Patent
active
060057270
ABSTRACT:
A servo decoder is disclosed for disc storage systems that operates according to a novel coding scheme capable of accurately decoding detected codewords representing servo track address during seek operations, even when the recording head flies between two adjacent tracks, and capable of correcting errors in the detected codedwords caused by noise in the read signal, such as inter-symbol interference. In a first embodiment, the coding scheme comprises an error correcting code (ECC) capable of correcting a predetermined number of bit errors in the detected codewords. To achieve the equivalent effect of a conventional Gray code, the codewords are arranged such that adjacent track addresses differ by a number of bits equal to the minimum distance of the ECC code. In a second embodiment, the servo code corrects certain minimum distance error events associated with a trellis type sequence detector. To achieve the equivalent effect of a conventional Gray code in this embodiment, the codewords are arranged such that adjacent track addresses differ by a number of bits relative to the minimum distance error events corrected. In this manner, when the recording head spans two adjacent tracks during a seek operation, the ambiguity in the detected codeword will be resolved in favor of one of the adjacent track addresses. Further, due to the error correcting capabilities of the code, the present invention improves the performance of servo seeking and tracking operations, and allows the servo data to be recorded at a higher density.
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Behrens Richard T.
Reed David E.
Turk Stephen A.
Zook Christopher P.
Cirrus Logic Inc.
Kim W. Chris
Neal Regina Y.
Sheerin Howard H.
Shifrin Dan A.
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