Techniques for implementing non-uniform constraints in modulation encoded data
First Claim
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1. A disk drive system comprising:
- a modulation encoder that imposes non-uniform modulation constraints on data to generate a constrained codeword; and
a multiplexer that inserts blocks of unconstrained data into more strongly constrained portions of the constrained codeword before the constrained codeword is stored on a disk.
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Abstract
Non-uniform modulation encoding techniques are provided to prevent data from containing bit patterns that are prone to errors during read back. Modulation encoding is performed on a data stream to remove error prone bit patterns. Unconstrained data, such as error check parity, that is inserted into the modulated data stream may contain error prone bit patterns. Stricter modulation constraints are enforced on bits that are next to the unconstrained data, than on the remaining bits. By enforcing stricter modulation constraints on these bits, an entire data bit stream can have a desired modulation constraint.
55 Citations
20 Claims
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1. A disk drive system comprising:
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a modulation encoder that imposes non-uniform modulation constraints on data to generate a constrained codeword; and a multiplexer that inserts blocks of unconstrained data into more strongly constrained portions of the constrained codeword before the constrained codeword is stored on a disk. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A disk drive controller chipset comprising:
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a modulation encoder that imposes a first constraint on a codeword starting at a first bit location and that imposes a second constraint on the codeword starting at a second bit location to generate an output codeword, wherein the second constraint is more strict than the first constraint; and a multiplexer that inserts a block of unconstrained data into a portion of the output codeword that is constrained according to the second constraint before the output codeword is stored on a disk. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for imposing modulation constraints on data, the method comprising:
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imposing non-uniform modulation constraints on a codeword to generate a constrained codeword; and inserting unconstrained data into a more strongly constrained portion of the constrained codeword before the constrained codeword is stored on a medium. - View Dependent Claims (17, 18, 19, 20)
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Specification