Hitachi Global Storage Technologies Netherlands B.v.

International Business Machines Corporation

Richard Michael Hamilton New

Bruce Alexander Wilson

Martin Aureliano Hassner

Barry Marshall Trager

Arvind M Patel

Spencer W Ng

Tetsuya Tamura

Modified HDD sector formats have multiple sets of preamble data. The preambles are well separated so that any defect long enough to wipe out both preambles would also overwhelm the ECC.

HDD sector format with reduced vulnerability to defects and burst errors

WORM safeguards are provided in a magnetic disk drive in which the disks are pre-magnetized or pre-recorded such that all magnetic domains on each recording surface are completely aligned pointing in the same direction. A special write head which can magnetically write only in the direction opposite to the pre-magnetization orientation is also provided.

System and method for WORM magnetic recording

A soft error correction algebraic decoder and an associated method use erasure reliability numbers to derive error locations and values. More specifically, symbol reliability numbers from a maximum likelihood (ML) decoder as well as a parity check success/failure from inner modulation code symbols are combined by a Reed-Solomon decoder in an iterative manner, such that the ratio of erasures to errors is maximized. The soft error correction (ECC) algebraic decoder and associated method decode Reed Solomon codes using a binary code and detector side information. The Reed Solomon codes are optimally suited for use on erasure channels. A threshold adjustment algorithm qualifies candidate erasures based on a detector error filter output as well as modulation code constraint success/failure information, in particular parity check or failure as current modulation codes in disk drive applications use parity checks. This algorithm creates fixed erasure inputs to the Reed Solomon decoder. A complementary soft decoding algorithm of the present invention teaches the use of a key equation solver algorithm that calculates error patterns obtained as a solution to a weighted rational interpolation problem with the weights given by the detector side information.

Soft error correction algebraic decoder

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San Jose, CA, United States of America

Richard Michael Hamilton New