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AssigneeMatsushita Electric Industrial Co.Ltd.
InventorsTakeshi Nakajima, Shigeru Furumiya, Yoshinari Takemura, Kenji Koishi
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A digital information playback apparatus comprises A/D converter that converts a playback signal into digital data, a maximum likelihood decoder that decodes the quantized data output from the A/D converter to obtain the original digital information, and a timing signal extractor that generates a sampling clock used in the A/D converter, and wherein the maximum likelihood decoder detects the response characteristic of the record/playback system and obtains level fluctuations contained in the playback signal, based on the survival path obtained as a maximum likelihood decoding result, to control the expected multilevel equalized values used in the maximum likelihood decoder, the timing signal extractor obtains level fluctuations, based on the survival path obtained as a maximum likelihood decoding result, and obtains the component of the level fluctuations due to phase shifts of the sampling clock of the VCO to control the phase of the sampling clock of the VCO.
A maximum likelihood decoder for reproducing original digital information using partial response equalization which is recorded on a recording medium by modulation with channel codes of the minimum distance between polarity inversions 3 or more, comprising:
A digital information playback apparatus for reducing original digital information from a recording medium using partial response equalization, said digital information playback apparatus comprising an A/D converter that converts a playback signal played back from said recording medium into quantized data, a maximum likelihood decoder that decodes said quantized data to obtain said original digital information, and a timing signal extractor that extracts, from among timing signals contained in said playback signal, only timing signals identified to be correct based on information output from said maximum likelihood decoder and outputs the extracted timing signals to feed back to said A/D converter for sampling said playback signal.
Dependencies are inferred from the claim text.