Method and apparatus for implementing PRML codes with maximum ones
AssigneeInternational Business Machines Corporation
InventorRichard L. Galbraith
Life of this patent
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Abstract
Apparatus and methods are provided for encoding a predefined number of bits of binary data into codewords having a predefined number of bits for a partial-response maximum-liklihood (PRML) data channel in a direct access storage device (DASD). Rate 8/9 block codes having maximum ones and run length constraints (0,8,12,.infin.) and (0,8,6,.infin.) provide timing and gain control and reduced susceptibility to misequalization effects in PRML channels.
Claims16
A method for encoding a predefined number of bits of binary data into codewords having a predefined number of bits for a partial-response maximum-likelihood (PRML) data channel in a direct access storage device (DASD) comprising the steps of:
- receiving the binary data;
- and
- generating sequences of codewords responsive to the received binary data;
- each of said generated codewords being included within a predetermined set of codewords, said codeword set having a maximum number of binary ones;
- said generated sequences of codewords having less than a first predetermined number of consecutive zeros;
- said generated sequences of codewords including two subsequences, one of said subsequences including odd bit positions and another of said subsequences including even bit positions, said subsequences having less than a second predetermined number of consecutive zeros.
Apparatus for encoding a predefined number of bits of binary data into codewords having a predefined number of bits for a partial-response maximum-likelihood (PRML) data channel in a direct access storage device (DASD) comprising:
- means for receiving the binary data;
- and
- means coupled to said receiving means for generating sequences of codewords responsive to the received binary data;
- each of said generated codewords being includes within a predetermined set of codewords, said codeword set having a maximum number of binary ones;
- said generated sequences of codewords having less than a first predetermined number of consecutive zeroes;
- said generated sequences of codewords including two subsequences, one of said subsequences including odd bit positions and another of said subsequences including even bit positions, said subsequences having less than a second predetermined number of consecutive zeroes.
Dependencies are inferred from the claim text.