US Patent No: 5,774,470

Number of patents in Portfolio can not be more than 2000

Digital signal processor, error detection method, and recording medium reproducer

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Abstract

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A playback signal processing circuit for reducing decode errors and enabling high-density digital magnetic recording and a digital magnetic recording reproducing unit using the playback signal processing circuit are provided. An estimated waveform generation circuit uses the decoding result of a PRML channel to generate an ideal playback signal waveform. A subtractor provides a waveform representing a difference between the waveform and an actual playback signal. There is a high probability that error bits will occur at an interval of two or four bits because of the nature of GCR code and maximum-likelihood decoding; in the error state of each bit, one bit is incremented by one with respect to the correct bit value and the other signal bit is decremented by one. From this fact, an error detection circuit discriminates an error difference waveform pattern and an error discrimination circuit detects an error bit interval, whereby an error correction circuit carries out error bit correction.

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Patent Owner(s)

Patent OwnerAddressTotal Patents
HITACHI GLOBAL STORAGE TECHNOLOGIES JAPAN, LTD.TOKYO575

International Classification(s)

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Ashikawa, Kazutoshi Maebashi, JP 9 111
Mita, Seiichi Kanagawa-ken, JP 83 1044
Miyazawa, Shoichi Yokohama, JP 33 353
Nishiya, Takushi Machida, JP 18 378
Shimokawa, Ryushi Takasaki, JP 12 89

Cited Art Landscape

Patent Info (Count) # Cites Year
 
MOTOROLA, INC. (5)
* 5,271,042 Soft decision decoding with channel equalization 71 1989
* 5,144,644 Soft trellis decoding 30 1989
* 5,113,400 Error detection system 38 1990
* 5,142,551 Signal weighting system for digital receiver 60 1991
* 5,263,052 Viterbi equalizer for radio receiver 13 1991
* Cited By Examiner

Patent Citation Ranking

Forward Cite Landscape

Patent Info (Count) # Cites Year
 
BROADCOM CORPORATION (3)
* 5,961,658 PR4 equalization and an EPR4 remod/demod sequence detector in a sampled amplitude read channel 45 1997
* 6,052,248 Parity channel code for enhancing the operation of a remod/demod sequence detector in a d=1 sampled amplitude read channel 40 1998
6,185,173 Sampled amplitude read channel employing a trellis sequence detector matched to a channel code constraint and a post processor for correcting errors in the detected binary sequence using the signal samples and an error syndrome 26 1998
 
KONINKLIJKE PHILIPS ELECTRONICS N.V. (3)
* 6,587,520 Generation of amplitude levels for a partial response maximum likelihood (PRML) bit detector 2 1999
7,058,142 Generation of amplitude levels for a partial response maximum likelihood (PRML) bit detector 2 2003
* 7,827,456 Error correction scheme for a disc-playing system 0 2005
 
CIRRUS LOGIC, INC. (2)
6,185,175 Sampled amplitude read channel employing noise whitening in a remod/demod sequence detector 42 1998
* 6,513,141 Sampled amplitude read channel employing a trellis sequence detector and a post processor for generating error metrics used to correct errors made by the trellis sequence detector 29 1999
 
DOLBY LABORATORIES LICENSING CORPORATION (2)
* 7,617,109 Method for correcting metadata affecting the playback loudness and dynamic range of audio information 9 2004
8,032,385 Method for correcting metadata affecting the playback loudness of audio information 3 2009
 
TEXAS INSTRUMENTS INCORPORATED (2)
* 6,546,518 Detector error suppression circuit and method 10 2000
* 7,016,445 Apparatus for and method of clock recovery from a serial data stream 9 2001
 
ASTECH INTERNATIONAL LLC (1)
6,397,173 Application specific waveform generator 6 1999
 
LUCENT TECHNOLOGIES INC. (1)
* 6,317,071 Method and apparatus for analog-to-digital conversion by combining digital sample values 4 2000
 
SEAGATE TECHNOLOGY LLC (1)
6,877,116 Method and apparatus for determining bit error rate in a sampled data system without requiring read channel circuitry 5 1998
 
SHARP KABUSHIKI KAISHA (1)
* 7,080,313 Signal evaluation apparatus and signal evaluation method 6 2002
* Cited By Examiner