JP2000187945A5 - - Google Patents

Description

[0009]
[Means for Solving the Problems]
Therefore, in the present invention, two prediction values corresponding to the vicinity of the central value (zero crossing) among the prediction values at the time of maximum likelihood decoding are provided, and when the asymmetric read signal is obtained by asymmetry, By reducing the error from the sample value, high-speed and highly reliable digital data can be reproduced. That is, the reproducing apparatus of the present invention comprises partial response equalization means for equalizing the read signal obtained from the recording medium on which the digital data is recorded with the partial response to convert it into a sample value sequence, and this sample value sequence And maximum likelihood decoding means for reproducing digital data by maximum likelihood decoding using a plurality of prediction values, wherein the maximum likelihood decoding means comprises sample values for two prediction values corresponding to the vicinity of the median value of the sample value sequence. Either prediction value is selected based on the trend of the series. Further, according to the reproduction method of the present invention, a partial response equalization step of performing waveform equalization by partial response to convert a read signal obtained from a recording medium having digital data recorded thereon into a sample value sequence, and converting a plurality of sample value sequences And maximum likelihood decoding to reproduce digital data using the prediction value of the maximum likelihood decoding step, and in this maximum likelihood decoding step, two prediction values corresponding to the vicinity of the median value of the sample value sequence are It chooses one based on the tendency of the.

Claims (17)

Partial response equalization means for performing waveform equalization with partial response to convert a read signal obtained from a recording medium on which digital data is recorded into a sample value sequence; and maximum likelihood using a plurality of predicted values for the sample value sequence And maximum likelihood decoding means for decoding and reproducing digital data;
The reproduction apparatus, wherein the maximum likelihood decoding means selects two of the predicted values corresponding to the vicinity of a median value of the sample value sequence based on the tendency of the sample value sequence. The reproduction apparatus according to claim 1, further comprising: first predicted value generation means for generating two predicted values corresponding to the vicinity of the median value from the sample value sequence by a predetermined algorithm. 3. The apparatus according to claim 2, wherein the first predicted value generation unit obtains first and second differences of the sample value series to generate a predicted value with a positive first difference and a predicted value with a negative first difference. Playback device. The reproduction according to claim 2, further comprising: second predicted value generation means for generating another predicted value by a predetermined algorithm based on the predicted value corresponding to the median generated by the first predicted value generation means. apparatus. 5. The apparatus according to claim 4, wherein said second predicted value generation means obtains an average value of sample values dispersed upward with respect to said median value and an average value of sample values dispersed downward among said sample value series. , These calculated averages,
A reproduction apparatus characterized by adding or subtracting a difference with respect to an average value of theoretical prediction values to generate other prediction values. 5. The apparatus according to claim 4, wherein the second predicted value generation unit generates a plurality of consecutive sample values of the sample value series as the highest predicted value or the lowest predicted value, and uses these predicted values in advance. The reproduction apparatus characterized in that the set coefficient is calculated to generate another prediction value between the prediction value corresponding to the median value. The reproduction apparatus according to claim 1, wherein the partial response equalizing means includes means for delay correcting the timing of obtaining the sample value sequence. 8. A reproduction apparatus according to claim 7, further comprising clock signal supply means for supplying a common clock signal to said conversion means, partial response equalization means and maximum likelihood decoding means. The reproduction apparatus according to claim 1, wherein the recording medium is an optical recording medium. A partial response equalization step of performing waveform equalization with a partial response to convert a read signal obtained from a recording medium having digital data recorded thereon into a sample value sequence;
And maximum likelihood decoding for reproducing the digital data by maximum likelihood decoding using the plurality of predicted values.
In the maximum likelihood decoding step, the two predicted values corresponding to the vicinity of the median value of the sample value sequence are selected based on the tendency of the sample value sequence. The method according to claim 10, further comprising a first predicted value generation step of generating two predicted values corresponding to the vicinity of the median value from the sample value series by a predetermined algorithm. 12. The method according to claim 11, wherein, in the first predicted value generation step, first and second differences of the sample value series are obtained to generate a predicted value with a positive first difference and a negative predicted value. How to play. The reproduction according to claim 11, further comprising a second prediction value generation step of generating another prediction value by a predetermined algorithm based on the prediction value corresponding to the median generated by the first prediction value generation means. Method. In claim 13, in the second predicted value generation step, an average value of sample values dispersed upward with respect to the median value and an average value of sample values dispersed downward are obtained respectively in the sample value series. And a difference with respect to the average value of theoretical prediction values is added to or subtracted from the calculated average value to generate another prediction value. In claim 13, in the second predicted value generation step, a plurality of consecutive sample values in the sample value series are generated as the highest predicted value or the lowest predicted value, and these predicted values are made in advance. The reproduction method characterized in that the set coefficients are calculated to generate other prediction values between the prediction value corresponding to the median value. 11. The reproduction method according to claim 10, wherein, in the partial response equalization step, a timing at which the sample value series is obtained can be delay corrected. The reproduction method according to claim 10, wherein the recording medium is an optical recording medium.

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