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公开(公告)号：GB2286952A
公开(公告)日：1995-08-30
申请号：GB9503986
申请日：1995-02-28
Applicant: IBM
Inventor： COKER JONATHAN DARREL , DOLIVO FRANCOIS BERNARD , GALBRAITH RICHARD LEO , HERMANN RETO , HIRT WALTER , VANNORSDEL KEVIN
IPC: G11B20/10 , G11B20/18 , H03H15/00 , H03H17/00 , H03H21/00 , H03M13/23 , H04B3/04 , H04L25/497 , G11B20/14
Abstract: A method and apparatus are provided for maximum-likelihood data detection in a partial-response (PR) data channel including a head and disk assembly providing an analog signal coupled to an analog to digital converter (ADC) providing digital samples. A plurality of digital samples are received from the ADC. The received digital samples are applied to a selected first filter 402 and a selected second filter 404. The first filtered digital samples are applied to a first data detector 406, and the second filtered digital samples are applied to a second data detector 408. A predetermined parameter is identified 410, and at least one of the first and second data detectors is selected responsive to the identified predetermined parameter. The detectors may comprise partial response, adaptive, full-state or reduced-state Viterbi detectors (e.g. PR4 or EPR4 Viterbi detectors).
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公开(公告)号：DE69327618D1
公开(公告)日：2000-02-24
申请号：DE69327618
申请日：1993-06-30
Applicant: IBM
Inventor： COKER JONATHAN DARREL , GALBRAITH RICHARD LEO
IPC: G11B5/00 , G11B5/012 , G11B5/09 , G11B5/84 , G11B19/04 , G11B20/10 , G11B20/18 , G11B33/10 , G06F11/00
Abstract: The invention provides a circuit and method for performing test procedures on a data storage and recovery system for a magnetic storage unit. Error sample values from a read operator in a data storage and recovery system are applied to a first and a second process path to generate output signals. A source of level samples of a logical data level is also provided. The first process path generates an output signal comprising the square of each error value sample. The second process path compares the error value samples and a compare level and generates an output signal comprising a result of each comparison. The output signal of the first process path, the second process path, or the level samples is selected and is associated with a data type. In response to a coincidence of a data type associated with the selected signal with a desired data type, the selected signal is gated and then accumulated. The window during which the selected signal is accumulated may vary. The accumulated value is used as an input variable to a selected test to determine the accuracy of the data storage and recovery system.
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公开(公告)号：SG42862A1
公开(公告)日：1997-10-17
申请号：SG1996000246
申请日：1992-05-20
Applicant: IBM
Inventor： COKER JONATHAN DARREL , DOLIVO FRANCOIS BERNARD , GALBRAITH RICHARD LEO , SCHOTT WOLFGANG HANS , ZIPEROVICH PABLO ALEJANDRO
Abstract: A method and apparatus are provided for controlling a digital filter function included in a data path within gain and timing control loops of a PRML magnetic recording channel. The digital filter function is removed from the data path during an acquisition mode and the digital filter function is restored to the data path during a tracking mode. A predetermined gain and a quantized delay at a synchronization frequency are provided when switching from acquisition mode to tracking mode. A unity gain and a delay of an integer number of sample periods are provided at a synchronization frequency when switching from acquisition mode to tracking mode.
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公开(公告)号：DE3750315D1
公开(公告)日：1994-09-08
申请号：DE3750315
申请日：1987-05-19
Applicant: IBM
Inventor： CHRISTENSEN THOMAS CHARLES , JAWORSKI RICHARD CASIMIR , COKER JONATHAN DARREL , KERWIN GREGORY JOHN , CUNNINGHAM EARL ALBERT , PALMER DEAN CURTIS , ROEPKE JEFFREY RALPH
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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Patent Agency Ranking
公开(公告)号：SG72817A1
公开(公告)日：2000-05-23
申请号：SG1998001079
申请日：1998-05-19
Applicant: IBM
Inventor： COKER JONATHAN DARREL , ELEFTHERIOU EVANGELOS STAVROS , GALBRAITH RICHARD LEO , HIRT WALTER
Abstract: A method and apparatus are provided for data detection for a partial-response maximum-likelihood (PRML) data detection channel in a direct access storage device. A class-IV partial response (PR4) signal is applied to a PR4 Viterbi detector to provide a PR4 Viterbi output and is applied to a first matching delay circuit to provide a delayed PR4 signal. The PR4 Viterbi output is subtracted from the delayed PR4 signal and a resulting signal is applied to a first filter having a frequency response of 1/(1- alpha D2). The filtered output signal is applied to a second filter providing a second filtered output signal. The PR4 Viterbi output is applied to a second matching delay circuit to provide a delayed PR4 Viterbi output signal. The delayed PR4 Viterbi output is corrected responsive to the second filtered output signal. The first filter is an infinite impulse response (IIR) filter and the filtered output signal represents whitened noise and modified PRML error events. The second filter is a matched filter used to identify dominant error events.
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公开(公告)号：SG65038A1
公开(公告)日：1999-05-25
申请号：SG1997004390
申请日：1997-12-08
Applicant: IBM
Inventor： COKER JONATHAN DARREL , GREENBERG RICHARD
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公开(公告)号：SG42844A1
公开(公告)日：1997-10-17
申请号：SG1996000072
申请日：1993-06-30
Applicant: IBM
Inventor： COKER JONATHAN DARREL , GALBRAITH RICHARD LEO
IPC: G11B5/00 , G11B5/012 , G11B5/09 , G11B5/84 , G11B19/04 , G11B20/10 , G11B20/18 , G11B33/10 , G06F11/00
Abstract: The invention provides a circuit and method for performing test procedures on a data storage and recovery system for a magnetic storage unit. Error sample values from a read operator in a data storage and recovery system are applied to a first and a second process path to generate output signals. A source of level samples of a logical data level is also provided. The first process path generates an output signal comprising the square of each error value sample. The second process path compares the error value samples and a compare level and generates an output signal comprising a result of each comparison. The output signal of the first process path, the second process path, or the level samples is selected and is associated with a data type. In response to a coincidence of a data type associated with the selected signal with a desired data type, the selected signal is gated and then accumulated. The window during which the selected signal is accumulated may vary. The accumulated value is used as an input variable to a selected test to determine the accuracy of the data storage and recovery system.
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公开(公告)号：DE69327618T2
公开(公告)日：2000-07-06
申请号：DE69327618
申请日：1993-06-30
Applicant: IBM
Inventor： COKER JONATHAN DARREL , GALBRAITH RICHARD LEO
IPC: G11B5/00 , G11B5/012 , G11B5/09 , G11B5/84 , G11B19/04 , G11B20/10 , G11B20/18 , G11B33/10 , G06F11/00
Abstract: The invention provides a circuit and method for performing test procedures on a data storage and recovery system for a magnetic storage unit. Error sample values from a read operator in a data storage and recovery system are applied to a first and a second process path to generate output signals. A source of level samples of a logical data level is also provided. The first process path generates an output signal comprising the square of each error value sample. The second process path compares the error value samples and a compare level and generates an output signal comprising a result of each comparison. The output signal of the first process path, the second process path, or the level samples is selected and is associated with a data type. In response to a coincidence of a data type associated with the selected signal with a desired data type, the selected signal is gated and then accumulated. The window during which the selected signal is accumulated may vary. The accumulated value is used as an input variable to a selected test to determine the accuracy of the data storage and recovery system.
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公开(公告)号：DE3750315T2
公开(公告)日：1995-03-09
申请号：DE3750315
申请日：1987-05-19
Applicant: IBM
Inventor： CHRISTENSEN THOMAS CHARLES , JAWORSKI RICHARD CASIMIR , COKER JONATHAN DARREL , KERWIN GREGORY JOHN , CUNNINGHAM EARL ALBERT , PALMER DEAN CURTIS , ROEPKE JEFFREY RALPH
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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