Optical disk, optical disk recording/reproduction apparatus, and optical disk signal quality evaluation method

An optical disk signal quality evaluation method for a reproduced equalized signal obtained by reproducing and equalizing a signal recorded on an optical disk medium by using embossing, or by using an optical data recording apparatus, comprising the steps of:

• designating an equalization error vk=(yk−Σak−ihi), wherein yk denotes the value of a signal reproduced and equalized for each clock cycle, ak denotes a predetermined data string and hk denotes a predetermined partial response characteristic, and designating a time delay operator D that uses a clock time as a unit;
• designating as a polynomial A(D)=ΣαjDj, which is defined by using αj, a coefficient of either 1, 0 or −1, and which satisfies αjαj+1≠−1, and designating H(D)=ΣhkDk as a PR polynomial that defines a partial response;
• based on a polynomial defined as N(D)=A(D)H(D)=ΣεiDi, calculating a signal quality evaluation value S that is defined by the following equation (18)
• S
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• and
• evaluating the quality of a signal recorded on an optical disk.

A signal quality evaluation apparatus, for a reproduced equalized signal yk that is obtained by reproducing and equalizing a signal that has been recorded in advance on an optical disk medium by using embossing or by using an optical data recording apparatus, comprising:

• a target signal generator for generating a target signal Σak−ihi based on a predetermined data string ak and a predetermined partial response characteristic hk;
• a computation unit for using the reproduced equalized signal yk and the target signal Σak−ihi to calculate an equalization error vk=(yk−Σak−ihi);
• and
• means for using auto-correlation for the equalization error to calculate a quality evaluation value for the reproduced equalized signal yk.

A signal quality evaluation apparatus, for a reproduced equalized signal yk that is obtained by reproducing and equalizing a signal that has been recorded in advance on an optical disk medium by using embossing or by using an optical data recording apparatus, comprising:

• a target signal generator for generating a target signal Σak−ihi based on a predetermined data string ak and a predetermined partial response characteristic hk;
• a computation unit for using the reproduced equalized signal yk and the target signal Σak−ihi to calculate an equalization error vk=(yk−Σak−ihi);
• a delay element group, including a plurality of delay elements, for receiving the equalization error, and for outputting equalization errors vk, vk−1, . . . and vk−1+1 a plurality of times;
• means for receiving the equalization errors vk, vk−1, . . . and vk−n+1 and for calculating Rn(n=0, 1, 2, . . . to L−1), based on the following equation (23), and outputting Rn;
• noise variance calculation means for performing weighting for Rn with a coefficient β0, β1, . . . or βL−1 to obtain a noise variance ΣβiRi and
• quality evaluation value calculation means for using the noise variance ΣβiRi to calculate a quality evaluation value for the reproduced equalized signal,
• wherein
• Rn=E {Vk, vk−n}, and E {xi, yj} is the average value of the product xiyi (23).

A signal quality evaluation apparatus, for a reproduced equalized signal yk that is obtained by reproducing and equalizing a signal that has been recorded in advance on an optical disk medium by using embossing or by using an optical data recording apparatus, comprising:

• a target signal generator for generating a target signal Σak−ihi based on a predetermined data string ak and a predetermined partial response characteristic (h0=1, h1=2, h2=2, h3=2, h4=1);
• a computation unit for using the reproduced equalized signal yk and the target signal Σak−ihi to calculate an equalization error vk=(yk−Σak−ihi);
• a delay element group, including a plurality of delay elements, for receiving the equalization error, and for outputting equalization errors vk, vk−1, . . . and vk−n+1 a plurality of times;
• means for receiving the equalization errors vk, vk−1, . . . and vk−n+1, and for calculating Rn(n=0, 1, 2, . . . to L−1), based on the following equation (24), and outputting Rn;
• noise variance calculation means for performing weighting for Rn with a coefficient β0, β1, . . . or βL−1 to obtain a noise variance ΣβiRi, and
• quality evaluation value calculation means for using the noise variance ΣβiRi to calculate a quality evaluation value for the reproduced equalized signal,
• wherein
• Rn=E {vk, vk−n}, and Σ{xi, yi} is the average value of the product xiyi (24).