Data reproducing apparatus and method
AssigneeNikon Corporation
InventorShinichi Tanaka
Life of this patent
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Abstract
When performing data reproduction based on the partial response method, a reference pattern detection circuit detects the reference pattern directly from the reproduced signal that is supplied from a low pass filter, and supplies a timing signal to a calculation circuit. Based on the timing signal, the calculation circuit determines threshold levels that are used for data decoding in a decoder circuit based on the output level of an A/D converter circuit. As a result, a sector mark, which previously was used as a reference mark for reference pattern detection, does not need to be provided in the recording medium, thereby increasing the recording capacity for user data.
Claims27
A data reproducing apparatus comprising:
- a PR equalization circuit that equalizes a reproduced signal of user data recorded on a recording medium based on a partial response method;
- an A/D converter circuit that samples an output signal of the PR equalization circuit to produce sample data based on a clock signal produced from the output signal of the PR equalization circuit;
- a decoder circuit that decodes the sample data output from the A/D circuit to generate reproduced data;
- a reference pattern detection circuit that receives the reproduced signal and detects when a reference pattern that is included in the reproduced signal is being reproduced, the reference pattern detection circuit having an output that indicates that the reference pattern is being reproduced;
- and
- a calculation circuit that determines a plurality of threshold levels based on the output from the reference pattern detection circuit and on the output from the A/D converter circuit, the determined threshold levels being supplied to the decoder circuit for use in decoding the sample data.
A reference pattern detection circuit for use in a data reproducing apparatus that uses a PR equalization circuit to equalize a reproduced signal of user data recorded on a recording medium based on a partial response method and an A/D converter circuit to sample an output signal of the PR equalization circuit to produce sample data based on a clock signal produced from the output signal of the PR equalization circuit, the reference pattern detection circuit having an input that receives the reproduced signal and an output that indicates when the reference pattern is being reproduced, the reference pattern detection circuit detecting when a reference pattern that is included in the reproduced signal is being reproduced by detecting whether a characteristic of the reference pattern is present in the reproduced signal.
A method of detecting the presence of a reference pattern in a reproduced signal read from a recording medium by a data reproducing apparatus that uses a PR equalization circuit to equalize the reproduced signal based on a partial response method, the method comprising:
- inputting the reproduced signal into a reference pattern detection circuit
- using the reference pattern detection circuit, detecting when the reference pattern is present in the reproduced signal by detecting whether a characteristic of the reference pattern is present in the reproduced signal;
- and
- outputting a signal from the reference pattern detection circuit that indicates when the reference pattern is present in the reproduced signal.
Dependencies are inferred from the claim text.