US 8,121,226 B2Granted

Method of evaluating a readout signal, and optical disc apparatus

AssigneesHitachi, Ltd., Hitachi-LG Data Storage, Inc.

InventorHiroyuki Minemura

Life of this patent

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Abstract

A method and optical disc apparatus for evaluating a quality of a read signal adapted to the PRML method by evaluating a binary code decoded from the read signal obtained by a head, in which an error bit sequence having one bit edge shift from the binary code is generated, a Euclidian distance is calculated on both a correct bit sequence and the error bit sequence with respect to a predetermined target signal level, assuming that the binary code is the correct bit sequence, a Euclidian distance difference between the Euclidian distance on the correct bit sequence and the Euclidian distance on the error bit sequence is calculated, an average Euclidian distance from the target signal level is calculated, a normalized sequence error is calculated, the binary code is evaluated using the normalized sequence error.

Claims13

Dependent claims

A computer-implemented method for evaluating a quality of a read signal obtained by using a head of an optical disc apparatus, and adapted to the Partial Response Maximum Likelihood (PRML) method by evaluating a binary code decoded from the read signal, comprising the steps of:

obtaining a read signal, by using a head of an optical disc apparatus;
decoding a binary code from the read signal obtained by the head of the optical disc apparatus;
generating an error bit sequence having one bit edge shift from the binary code decoded from the read signal obtained by a head of an optical disc apparatus;
calculating, using a Euclidian distance calculator, an Euclidian distance on the error bit sequence with respect to a predetermined target signal level, and calculating an Euclidian distance on the binary code under the assumption that the binary code has a correct bit sequence;
calculating, using a Euclidian distance difference calculator, a Euclidian distance difference defined as a difference between the Euclidian distance on the binary code assumed to have a correct bit sequence and the Euclidian distance on the error bit sequence;
calculating, using an average Euclidian distance calculator, an average Euclidian distance from the target signal level, the average Euclidian distance corresponding to a 1-bit shift pattern of the target signal level;
calculating, using a normalized sequence error calculator, a normalized sequence error by subtracting the average Euclidean distance from the Euclidean distance difference and then dividing the result of subtraction by the average Euclidean distance;
and
evaluating, using a computer, a signal quality of the binary code assumed to have a correct bit sequence, by using the normalized sequence error.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/285,892Filed 16 Oct 2008 · continuation
Priority: JP 2004-1385307 May 2004
Published: US 2009/0052595 A126 Feb 2009
Granted: 21 Feb 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

G11B 20/10009
Digital recording or reproducing: improvement or modification of read or write signals
G11B 20/10083
Using partial response filtering when writing the signal to the medium or reading it therefrom: pR1 or PR, i.e. partial response class 1,…
G11B 20/10092
Using partial response filtering when writing the signal to the medium or reading it therefrom: partial response PR
G11B 20/10101
Using partial response filtering when writing the signal to the medium or reading it therefrom: pR2 or PR, i.e. partial response class 2,…

Family

Application11/044,070Parent of this continuation · filed 28 Jan 2005
US 2009/0052595 A1Pre-grant publication · published 26 Feb 2009
US 7,440,522 B2Parent of this continuation
US 2005/0249318 A1Published application
US 8,121,226 B2This patent

From the US filing history. Foreign family members aren’t listed.