| 摘要 |
PROBLEM TO BE SOLVED: To reduce the error correcting probability in the demodulation and to increase the recording density by forming a block unit made to the product code in the manner of adding the prescribed number of parity bits to each row and each column of digital information and recording them while adding the error detecting codes for each sector. SOLUTION: By a modulation circuit 14, one block is formed in such a manner that the prescribed number of parity bits are added to symbol data arrayed in the row direction and column direction to make the product code and also the recording is made on a recording medium 1 for every block by adding the error detecting codes for each sector. By a data control circuit 15, at the time of demodulation, a signal is read from the designated block and accumulated in a buffer memory 16. By an error correcting circuit 17, the signal is read out from the memory 16 and when the error correction is processed, the corrections in the row and column directions are altenately repeated till the error correction is completed. By this procedure, the burst error is eliminated and the thinning of a protecting layer on the recording medium is attained, then in company therewith, the numerical aperture of an objective lens is made to be larger than the high density recording is attained. |
