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公开(公告)号：JPH1125602A
公开(公告)日：1999-01-29
申请号：JP13358298
申请日：1998-05-15
Applicant: IBM
Inventor： COKER JONATHAN D , EVANGEROS S EREFUMORIU , GALBRAITH RICHARD L , WALTER HIRTH
Abstract: PROBLEM TO BE SOLVED: To provide a method and device for detecting the data of a partial response maximum liklihood (PRML) data channel in a direct access storage device. SOLUTION: A class IV partial response (PR4) signal is applied to a PR4 viterbi detector 60, and a PR4 viterbi output is generated, and is applied to a first matching delay circuit 64, and a delay PR4 signal is generated. The PR4 viterbi output is subtracted from the delay PR4 signal, and a synthetic signal is applied to a first filter 74 having a frequency response 1/ (1-αD ). A filtered output signal is applied to a second filter 76, and a second filter output signal is generated. The PR4 viterbi output is applied to a second matching delay circuit 86, and a delay PR4 viterbi output signal is generated. The delay PR4 viterbi output is responded to the second filter output signal to be corrected. The first filter is an infinite impulse response (IIR) filter, and the filter output signal shows a white colored noise and a corrected PRML error event.
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Patent Agency Ranking
公开(公告)号：GB2355165B
公开(公告)日：2003-10-22
申请号：GB0016683
申请日：2000-07-07
Applicant: IBM
Inventor： CIDECIYAN ROY D , COKER JONATHAN D , ELEFTHERIOU EVANGELOS , GALBRAITH RICHARD L , TRUAX TODD
IPC: G11B20/14 , G11B20/18 , H03M5/14 , G06F11/10 , H03M7/14 , H03M7/42 , H03M13/01 , H03M13/05 , H03M13/31 , H04L1/00 , H04L25/49
Abstract: A method and apparatus for encoding a plurality of successive m-bit binary data words to produce a plurality of successive of n-bit binary code words, where n and m are positive integers and n is greater than m, for supply to a magnetic recording channel. Each m-bit binary data word is partitioned into a plurality of blocks of bits, and at least one said blocks of bits in each m-bit binary data word is encoded in accordance with a finite-state coding scheme to produce a plurality of successive n-bit binary code words. At least one stage of violation correction which transforms the plurality of successive n-bit binary code words. Violation correction includes detecting the occurrence of any of a plurality of prohibited bit patterns at one or more predetermined locations within each n-bit binary coded word, and replacing any prohibited bit pattern so detected by a corresponding substitute bit pattern. The finite-state coding scheme, the prohibited bit patterns, and corresponding substitute bit patterns are predetermined such that in a serial bit-steam comprising the successive n-bit binary code words, the maximum number of consecutive bits of a first value is limited to a first predetermined number j, where b greater or equal to 2, and the maximum number of consecutive bits of the a second value is limited to a second predetermined number k.
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公开(公告)号：GB2355165A
公开(公告)日：2001-04-11
申请号：GB0016683
申请日：2000-07-07
Applicant: IBM
Inventor： CIDECIYAN ROY D , COKER JONATHAN D , ELEFTHERIOU EVANGELOS , GALBRAITH RICHARD L , TRUAX TODD
IPC: G11B20/14 , G11B20/18 , H03M5/14 , G06F11/10 , H03M7/14 , H03M7/42 , H03M13/01 , H03M13/05 , H03M13/31 , H04L1/00 , H04L25/49
Abstract: Methods and apparatus are provided 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. Each m-bit data word is partitioned into a plurality of blocks of bits (5a, 6a, 7a), and at least one of said blocks is encoded (5, 6, 7) in accordance with a block coding scheme such that the resulting bit sequence derived from the m bits of the data word comprises an n-bit sequence (5b, 6b, 7b). An n-bit code word is then produced by at least one stage of violation correction (8,9). The or each stage of violation correction comprises detecting the occurrence of any of a plurality of prohibited bit patterns at one or more predetermined locations in the n-bit sequence, and replacing any prohibited bit pattern so detected by a respective substitute bit pattern (8b, 9b). The block coding scheme and the prohibited and substitute bit patterns are predetermined such that, in a succession of said n-bit code words, the maximum number of consecutive bits of one value is limited to a first predetermined number j, where j / 2, and the maximum number of consecutive bits of the other value is limited to a second predetermined number k.
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公开(公告)号：HU0103435A2
公开(公告)日：2002-01-28
申请号：HU0103435
申请日：1999-08-31
Applicant: IBM
Inventor： BUSH GREGORY S , CIDECIYAN ROY D , COKER JONATHAN D , ELEFTHERIOU EVANGELOS S , GALBRAITH RICHARD L , STANEK DAVID J
IPC: G06F11/08 , G06F11/10 , G11B20/10 , G11B20/18 , G11B20/22 , H03M13/00 , H03M13/39 , H04L25/03 , H04L25/497
Abstract: A noise-predictive data detection method and apparatus are provided for enhanced noise-predictive maximum-likelihood (NPML) data detection in a direct access storage device. A data signal from a data channel in the direct access storage device is applied to a maximum-likelihood detector that provides an estimated sequence signal. A noise bleacher filter having a frequency response of (1+ alpha D)/1- beta D2) receives a combined estimated sequence signal and data signal and provides a noise filtered signal. A matching and error event filter receives the noise filtered signal and provides an error event filtered signal. An error correction unit receives the estimated sequence signal from the maximum-likelihood detector and receives the error event filtered signal and provides an error corrected estimated sequence signal.
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公开(公告)号：CA1274623A
公开(公告)日：1990-09-25
申请号：CA535599
申请日：1987-04-27
Applicant: IBM
Inventor： CHRISTENSEN THOMAS C , COKER JONATHAN D , CUNNINGHAM EARL A , JAWORSKI RICHARD C , KERWIN GREGORY J , PALMER DEAN C , ROEPKE JEFFREY R
Abstract: DISK DRIVE OPTIMIZED CHANNEL CIRCUIT A magnetic disk drive channel circuitry is shown and described that generates eight incremental values of write current and eight incremental values of delta-V (the minimum voltage change per unit time which tests signals to discriminate between data and noise). Each of these variable parameter values may be program selected by a three bit bus signal. This variability testing of and adaptation to the optimum parameter value for each head media combination and by grouping tracks in contiguous data bands, the parameters may be optimized for tracks near the inner diameter, the outer diameter and in the middle band. The variable delta-V can also be used as an additional data recovery tool wherein re-reading with a lower value enhances recovery of missing bit errors and re-reading with an increased value can assist recovery from an extra bit error.
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公开(公告)号：BR8702794A
公开(公告)日：1988-03-01
申请号：BR8702794
申请日：1987-06-01
Applicant: IBM
Inventor： CHRISTENSEN THOMAS C , COKER JONATHAN D , CUNNINGHAM EARL A , JAWORSKI RICHARD C , KERWIN GREGORY J , PALMER DEAN C , ROEPKE JEFFREY R
Abstract: A magnetic disk drive channel circuitry is shown and described that generates eight incremental values of write current and eight incremental values of delta-V (the minimum voltage change per unit time which tests signals to discriminate between data and noise). Each of these variable parameter values may be program selected by a three bit bus signal. This variability testing of and adaptation to the optimum parameter value for each head media combination and by grouping tracks in contiguous data bands, the parameters may be optimized for tracks near the inner diameter, the outer diameter and in the middle band. The variable delta-V can also be used as an additional data recovery tool wherein re-reading with a lower value enhances recovery of missing bit errors and re-reading with an increased value can assist recovery from an extra bit error.
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