IE83723B1 - A data detector system - Google Patents

A data detector system Download PDF

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Publication number
IE83723B1
IE83723B1 IE2003/0747A IE20030747A IE83723B1 IE 83723 B1 IE83723 B1 IE 83723B1 IE 2003/0747 A IE2003/0747 A IE 2003/0747A IE 20030747 A IE20030747 A IE 20030747A IE 83723 B1 IE83723 B1 IE 83723B1
Authority
IE
Ireland
Prior art keywords
dimension
detector
symbol
estimates
detectors
Prior art date
Application number
IE2003/0747A
Other versions
IE20030747A1 (en
Inventor
Conway Thomas
Original Assignee
University Of Limerick
Filing date
Publication date
Application filed by University Of Limerick filed Critical University Of Limerick
Priority to IE2003/0747A priority Critical patent/IE83723B1/en
Publication of IE20030747A1 publication Critical patent/IE20030747A1/en
Publication of IE83723B1 publication Critical patent/IE83723B1/en

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/10009—Improvement or modification of read or write signals
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/10009—Improvement or modification of read or write signals
    • G11B20/10037—A/D conversion, D/A conversion, sampling, slicing and digital quantisation or adjusting parameters thereof
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/10009—Improvement or modification of read or write signals
    • G11B20/10268—Improvement or modification of read or write signals bit detection or demodulation methods
    • G11B20/10287—Improvement or modification of read or write signals bit detection or demodulation methods using probabilistic methods, e.g. maximum likelihood detectors
    • G11B20/10296—Improvement or modification of read or write signals bit detection or demodulation methods using probabilistic methods, e.g. maximum likelihood detectors using the Viterbi algorithm
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/12—Formatting, e.g. arrangement of data block or words on the record carriers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/18—Error detection or correction; Testing, e.g. of drop-outs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/12—Formatting, e.g. arrangement of data block or words on the record carriers
    • G11B20/1217—Formatting, e.g. arrangement of data block or words on the record carriers on discs
    • G11B2020/1249—Formatting, e.g. arrangement of data block or words on the record carriers on discs wherein the bits are arranged on a two-dimensional hexagonal lattice
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • G11B7/013—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track for discrete information, i.e. where each information unit is stored in a distinct discrete location, e.g. digital information formats within a data block or sector
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/14—Heads, e.g. forming of the optical beam spot or modulation of the optical beam specially adapted to record on, or to reproduce from, more than one track simultaneously
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/2407—Tracks or pits; Shape, structure or physical properties thereof
    • G11B7/24085—Pits
    • G11B7/24088—Pits for storing more than two values, i.e. multi-valued recording for data or prepits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/29—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/37—Decoding methods or techniques, not specific to the particular type of coding provided for in groups H03M13/03 - H03M13/35
    • H03M13/39—Sequence estimation, i.e. using statistical methods for the reconstruction of the original codes
    • H03M13/3905—Maximum a posteriori probability [MAP] decoding or approximations thereof based on trellis or lattice decoding, e.g. forward-backward algorithm, log-MAP decoding, max-log-MAP decoding
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/37—Decoding methods or techniques, not specific to the particular type of coding provided for in groups H03M13/03 - H03M13/35
    • H03M13/39—Sequence estimation, i.e. using statistical methods for the reconstruction of the original codes
    • H03M13/41—Sequence estimation, i.e. using statistical methods for the reconstruction of the original codes using the Viterbi algorithm or Viterbi processors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/63—Joint error correction and other techniques
    • H03M13/6343—Error control coding in combination with techniques for partial response channels, e.g. recording

Abstract

ABSTRACT A detector system detects values on a storage medium where there is ISI. The symbols are stored as pits in a close hexagonal lattice having u, v, and x dimensions at mutual 60° separations from an individual pit. The value for a particular symbol is determined by generating an estimate for the symbol in each of the u, v, and x dimensions. These estimates are used to generate a decision for the symbol as it is at the intersection of these dimensions. Thus a number of (1) -dimensional detectors can be used although the platform is two—dimensional and ISI.

Description

A data detector system” INTRODUCTION Field of the Invention The invention relates to a system for data detection and recovery from an optical data storage medium.
Prior Art Discussion In the field of data storage and recovery there have been many attempts to provide reliable data storage and recovery with improved storage densities and optimum read output. Some of the approaches of the prior art are discussed below.
Fig. A illustrates a simple data storage and recovery arrangement in which a transducer produces a signal in response to data stored in a region of an optical storage medium. There are physical limitations associated with transducers, for example optical disks are read using a focused light spot from a laser but the minimum diameter of the spot is limited by diffraction to a size of the order of the light wavelength used. Data is stored with a data bit 1 represented as a pit in the medium, which reduces the reflected light intensity and a data bit 0 represented with the absence of a pit! The data is recovered by comparing the received signal to a reference level. In the illustrated the bit sizes are greater than the spot size and can be individually defitegtgd. However storage density is limited by the size of the spot.
Referring to Fig. B, this is an example of data storage in which data bit size has been reduced, and in which the tracks are separated by a distance by a guard band in the “Vertical” direction but there may still be interference in the horizontal direction.

Claims (1)

1. Claims A method of processing stored data read from a storage medium in which the data is stored in a lattice arrangement of symbols, the method comprising the steps of: (a) a detector generating an estimate for each symbol in a linear dimension; (b) a detector generating an estimate for each symbol in a different non- orthogonal linear dimension; and (c) a processor using all estimates to generate a decision for a symbol at the intersection of the dimensions. A method as claimed in claim 1, wherein the method comprises the further step of generating a set of estimates for a third linear dimension intersecting the symbol, and additionally using these estimates for the decision. A method as claimed in claims 1 or 2, wherein the lattice is hexagonal. A method as claimed in claim 3, wherein the method comprises the further step of generating a set of estimates for a third linear dimension intersecting the symbol, and additionally using these estimates for the decision; and the three dimensions intersect the intersection symbol at 60° mutual angles. A method as claimed in any preceding claim, wherein soft decision detectors are used for the dimension estimates, and a Viterbi decoder is used for the symbol decision. A method as claimed in claim 5, wherein the Viterbi detector also generates an estimate for a dimension before generating the symbol decision. A method as claimed in any preceding claim, wherein the detectors for each dimension implement a l+D MAP algorithm. A method as claimed in any preceding claim, comprising the further steps of iterating by feeding back estimates for the symbols of a final dimension to the preceding dimension detectors as a priori information. A method as claimed in claim 8, wherein the iterations are performed by different detectors. A system as claimed in any preceding claim, wherein a detector for a first dimension has more status than one for a second dimension, and a detector for the second dimension has more status than one for a third dimension, said detectors being in series. A system as claimed in claim 10, wherein said first detector has five states with inputs 0, 1, 2, 3, 4, the second detector has three states with inputs 0, l, 2, and the third detector has two states with inputs 0, l. A method as claimed in any preceding claim, wherein estimates are generated for each dimension in parallel by detectors receiving input samples in parallel. A method as claimed in claim 11, wherein outputs of each detector are fed back to the other detectors. A system as claimed in any preceding claim, wherein a first dimension estimate detector implements a folded trellis with mapping to a reduced number of states. A system as claimed in claim 14, wherein all even states are mapped to an even state and all odd states are mapped to an odd state. A data detector system comprising detectors and a processor for performing a method as claimed in any preceding claim.
IE2003/0747A 2003-10-08 A data detector system IE83723B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
IE2003/0747A IE83723B1 (en) 2003-10-08 A data detector system

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IEIRELAND08/10/20022002/0803
IE20020803 2002-10-08
IE2003/0747A IE83723B1 (en) 2003-10-08 A data detector system

Publications (2)

Publication Number Publication Date
IE20030747A1 IE20030747A1 (en) 2004-04-21
IE83723B1 true IE83723B1 (en) 2004-12-30

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