Maximum transition run encoding and decoding systems
AssigneeInternational Business Machines Corporation
InventorsRoy D. Cideciyan, Jonathan D. Coker, Evangelos S. Eleftheriou, Richard L. Galbraith, Dave James Stanek
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Abstract
Maximum transition run encoding of a succession of M-bit data words to produce a succession of N-bit code words, where N→−M, for supply to a magnetic recording channel is described. Each M-bit data word is encoded in accordance with an MTR coding scheme to produce a G-bit word, where N→−G→M, such that the maximum number of consecutive bits of a first value, generally bits of value “1”, in a succession of the G-bit words is limited to a first predetermined value j1. The G-bit word is then encoded to produce an N-bit word in accordance with a second coding scheme.
Claims49
A method for encoding a succession of M-bit data words to produce a succession of N-bit code words, where N>M, for supply to a magnetic recording channel, the method comprising the steps of:
- encoding each M-bit data word in accordance with an MTR coding scheme to produce a G-bit word, where N>G>M, such that the maximum number of consecutive bits of a first value in a succession of said G-bit words is limited to a first predetermined value j1;
- and
- encoding said G-bit word to produce a said N-bit word in accordance with a second coding scheme wherein at least one parity bit, dependent on the bit-values of said G-bit word, is generated, such that the N-bit word satisfies a predetermined parity condition, and wherein bits of said first value in the G-bit word are mapped to respective bits of the N-bit word which are each of different value to the immediately preceding bit in the N-bit word;
- wherein the second coding scheme is such that, in a succession of said N-bit words, the maximum number of consecutive bits which are each of different value to the immediately preceding bit is limited to a second predetermined value j2.
Apparatus for encoding a succession of M-bit data words to produce a succession of N-bit code words, where N>M, for supply to a magnetic recording channel, the apparatus comprising:
- a first encoder for encoding each M-bit data word in accordance with an MTR coding scheme to produce a G-bit word, where N>G>M, such that the maximum number of consecutive bits of a first value in a succession of said G-bit words is limited to a first predetermined value j1;
- and
- a second encoder for encoding said G-bit word to produce a said N-bit word in accordance with a second coding scheme whereby the second encoder generates at least one parity bit, dependent on the bit-values of said G-bit word, such that the N-bit word satisfies a predetermined parity condition, and maps bits of said first value in the G-bit word to respective bits of the N-bit word which are each of different value to the immediately preceding bit in the N-bit word;
- wherein the second coding scheme is such that, in a succession of said N-bit words, the maximum number of consecutive bits which are each of different value to the immediately preceding bit is limited to a second predetermined value j2.
A data storage system comprising:
- encoder apparatus for encoding a succession of M-bit data words to produce a succession of N-bit code words, where N>M, for supply to a magnetic recording channel, the encoder apparatus comprising:a first encoder for encoding each M-bit data word in accordance with an MTR coding scheme to produce a G-bit word, where N>G>M, such that the maximum number of consecutive bits of a first value in a succession of said G-bit words is limited to a first predetermined value j1;
- and a second encoder for encoding said G-bit word to produce a said N-bit word in accordance with a second coding scheme whereby the second encoder generates at least one parity bit, dependent on the bit-values of said G-bit word, such that the N-bit word satisfies a predetermined parity condition, and maps bits of said first value in the G-bit word to respective bits of the N-bit word which are each of different value to the immediately preceding bit in the N-bit word, the second coding scheme being such that, in a succession of said N-bit words, the maximum number of consecutive bits which are each of different value to the immediately preceding bit is limited to a second predetermined value j2;
- a recording channel comprising means for recording a succession of said N-bit code words on a magnetic recording medium, and means for reading the magnetic recording medium to generate reproduced data corresponding to said N-bit code words;
- and
- processing apparatus comprising:a detector for processing the reproduced data in dependence on said predetermined parity condition to detect the N-bit code words corresponding thereto;
- a first decoder for decoding each N-bit code word in accordance with a decoding scheme which is the inverse of said second encoding scheme to produce the corresponding said G-bit word;
- and a second decoder for decoding each G-bit word in accordance with an MTR decoding scheme which is the inverse of said MTR encoding scheme to recover the corresponding said M-bit data word.
Dependencies are inferred from the claim text.