Information reproducing apparatus and reproducing method

An information reproducing method of decoding a signal reproduced from a recording medium corresponding to Viterbi decoding method, data thereon having been recorded with an RLL code, wherein said recording medium has a plurality of areas including an address area and a recordable area each having different reproduced signal qualities, comprising the steps of:

• calculating a branch metric in each of a plurality of statuses with an input reproduced signal and an amplitude reference value, and selecting a maximum likelihood status transition with an added value of the calculated branch metric and a past path metric;
• updating the amplitude reference value, depending upon which of said plurality of areas said input reproduced signal is reproduced from, with the selected maximum likelihood status transition and the input reproduced signal corresponding to each of a plurality of clock pulses;
• and
• setting an initial value of the amplitude reference value corresponding to a plurality of reproducing operations.

An information reproducing method of reproducing data on a recording medium corresponding to Viterbi decoding method, the data having been recorded with an RLL code, comprising the steps of:

• calculating a branch metric in each of a plurality of statuses with an input reproduced signal and an amplitude reference value and for selecting a maximum likelihood status transition with an added value of the calculated branch metric and a past path metric;
• updating the amplitude reference value with the selected maximum likelihood status transition and the input reproduced signal corresponding to each of a plurality of clock pulses;
• and
• setting an initial value of the amplitude reference value corresponding to a plurality of reproducing operations,
• wherein the recording medium has a plurality of types of areas,
• wherein said step of updating updates the amplitude reference value corresponding to each of the areas, and
• wherein said step of updating comprises:
• recognizing the maximum likelihood status transition received from said step of calculating with a status data value, and selecting said amplitude reference value for an area from which said input reproduced signal is obtained corresponding to the recognized status transition;
• mixing the amplitude reference value selected by said step of recognizing and the input reproduced signal at which the recognized status transition is selected in a predetermined ratio;
• and
• storing an output value of said step of mixing.

An information reproducing apparatus for reproducing data on a recording medium corresponding to Viterbi decoding method, the data having been recorded with an RLL code, the apparatus comprising:

• a Viterbi decoder configured to calculate a branch metric in each of a plurality of statuses with an input reproduced signal and an amplitude reference value and to select a maximum likelihood status transition with an added value of the calculated branch metric and a past path metric;
• an amplitude reference value adapting block configured to update the amplitude reference value with the selected maximum likelihood status transition and the input reproduced signal corresponding to each of a plurality of clock pulses;
• and
• a processor configured to set an initial value of the amplitude reference value corresponding to a plurality of reproducing operations,
• wherein the recording medium has a plurality of types of areas,
• wherein said processor is further configured to update the amplitude reference value corresponding to each of the areas, and
• wherein said processor has:
• amplitude reference value selecting means for recognizing the maximum likelihood status transition received from said Viterbi decoder with a status data value and for selecting said amplitude reference value for an area from which said input reproduced signal is obtained corresponding to the recognized status transition;
• mixing means for mixing the amplitude reference value selected by said amplitude reference value selecting means and the input reproduced signal at which the recognized status transition is selected in a predetermined ratio;
• and
• storing means for storing an output value of said mixing means.