Coded data generation or conversion – Digital code to digital code converters – To or from minimum d.c. level codes
Patent
1997-03-19
1998-12-01
Williams, Howard L.
Coded data generation or conversion
Digital code to digital code converters
To or from minimum d.c. level codes
360 40, G11B 509, H03M 746
Patent
active
058445099
ABSTRACT:
A synchronous read channel is disclosed which samples an analog read signal from a magnetic read head positioned over a magnetic disk medium, filters the sample values according to a desired partial response, extracts timing information from the filtered sample values, and detects an estimated data sequence from the filtered sample values using a discrete time sequence detector. The read channel employs a Data Randomizer which processes unencoded user data to insure that the channel bit patterns with worst-case pattern sensitivity occur no more frequently than would be expected from random user data. The Data Randomizer employs two linear feedback shift registers: one generates a 63-bit sequence which is EXLUSIVE-OR-ed against the MSB of each pair of data bits, the other generates a 127-bit sequence which is EXCLUSIVE-OR-ed against the LSB of each pair of data bits. The Data Randomizer does not affect error propagation. When the Data Randomizer is enabled, the probability of encountering any specific pattern of length n channel bits at a randomly selected location within encoded data is approximately 1/2.sup.n.
REFERENCES:
patent: 4118686 (1978-10-01), Lender
patent: 4314286 (1982-02-01), Hardwick
patent: 4490691 (1984-12-01), Dolby
patent: 4506305 (1985-03-01), Cardero
patent: 4535371 (1985-08-01), Harr et al.
patent: 4609907 (1986-09-01), Adler et al.
patent: 4613913 (1986-09-01), Phillips
patent: 4644564 (1987-02-01), Dolivo et al.
patent: 4646281 (1987-02-01), Verboom
patent: 4684921 (1987-08-01), Fok et al.
patent: 4688016 (1987-08-01), Fok
patent: 4774601 (1988-09-01), Ouchi et al.
patent: 4849834 (1989-07-01), Allen
patent: 4945538 (1990-07-01), Patel
patent: 4949196 (1990-08-01), Davie et al.
patent: 4953041 (1990-08-01), Huber
patent: 4978955 (1990-12-01), Howell
patent: 4993029 (1991-02-01), Galbraith et al.
patent: 5028922 (1991-07-01), Huang
patent: 5047767 (1991-09-01), Weathers et al.
patent: 5062011 (1991-10-01), Hase et al.
patent: 5107379 (1992-04-01), Huber
patent: 5121260 (1992-06-01), Arakawa et al.
patent: 5121263 (1992-06-01), Kerwin et al.
patent: 5150379 (1992-09-01), Baugh et al.
patent: 5220466 (1993-06-01), Coker et al.
patent: 5231545 (1993-07-01), Gold
patent: 5253125 (1993-10-01), Erikson et al.
patent: 5255313 (1993-10-01), Coker et al.
patent: 5258933 (1993-11-01), Johnson et al.
patent: 5260703 (1993-11-01), Nguyen et al.
patent: 5282216 (1994-01-01), Patel et al.
patent: 5287385 (1994-02-01), Sugawara et al.
patent: 5291499 (1994-03-01), Behrens et al.
patent: 5291500 (1994-03-01), Patel et al.
patent: 5311178 (1994-05-01), Pan et al.
patent: 5321559 (1994-06-01), Nguyen et al.
patent: 5329554 (1994-07-01), Behrens et al.
patent: 5341249 (1994-08-01), Abbott et al.
patent: 5341386 (1994-08-01), Shimoda et al.
patent: 5343340 (1994-08-01), Boutaghou et al.
patent: 5345342 (1994-09-01), Abbott et al.
patent: 5359631 (1994-10-01), Behrens et al.
patent: 5363112 (1994-11-01), Hatcher
patent: 5392295 (1995-02-01), Coker et al.
patent: 5712863 (1998-01-01), Gray
patent: 5771127 (1998-06-01), Reed et al.
patent: 5786950 (1998-07-01), Zook et al.
Roy D. Cideciyan et al., "A PMRL System for Digital Magnetic Recording," IEEE Journal on Selected Areas in Communications, vol. 10, No. 1, pp. 38-56, Jan. 1992.
J. Hong et al., "An Experimental 180 Mb/sec PRML Channel for Magnetic Recording," IBM Storage Systems Products Division, vol. 27, No. 6, Nov. 1991.
J.D. Coker et al., "Implementation of PRML in a Rigid Disk Drive," IBM Storage Systems Products Division, vol. 27, No. 6, 1991.
T.J. Schmerbeck, "A 27 Mhz Mixed Analog/Digital Magnetic Recording Channel DSP Using Partial Response Signaling with Maximum Likelihood Detection," IEEE International Solid-state Circuits Conference, pp. 136-137, 1991.
K. Knudson et al., "Producing Soft-Decision Information at the Output of a Class IV Partial Response Viterbi Detector," IEEE International Conference on Communications, Denver, vol. 2 of 3, pp. 26.5.1-26.5.5, Jun. 1991.
K. Chopra et al., "A Soft Decision Detection Method for Run-Length Limited Recording Channels," Maple Press Jan. 1990.
R. Behrens and A. Armstrong, "An Advanced Read/Write Channel for Magnetic Disk Storage," IEEE Twenty-Sixth Asilomar Conference on Signals, Systems & Computers, vol. 2, pp. 956-960, Oct. 1992.
H.K. Thapar et al., "A Class of Partial Response Systems for Increasing Storage Density in Magnetic Recording," IEEE Transactions on Magnetics, vol. MAG-23, No. 5, Sep. 1987.
William L. Abbott et al., "Channel equalization Methods for Magnetic Storage," IEEE, pp. 1618-1622, 1989.
William L. Abbott et al., "Performance of Digital Magnetic Recording with Equalization and Offtrack Interference," IEEE Transactions on Magnetics, vol. 27, No. 1, Jan. 1991.
Behrens Richard T.
Dudley Trent
Glover Neal
Cirrus Logic Inc.
Jean Pierre Peguy
Sheerin Howard H.
Shifrin Dan A.
Williams Howard L.
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