Patent ID: 7178092
Filing Date: 2007-02-13
Classification: G11B,H03M

Abstract:
1. A disk drive, comprising: a head to read and write data from and to a disk medium; and a read/write channel that operates as a signal processing unit and processes a record data signal or a reproduction data signal transmitted to or from the head, the read/write channel having a concatenated turbo codec, wherein the concatenated turbo codec includes an RSC encoder which encodes a record data sequence into a recursive systematic convolutional code sequence for data recording and a puncture unit which executes a decimation process on the recursive systematic convolutional code sequence at such a decimation rate that a predetermined error rate is ensured in a decoding system, the puncture unit is configured to delete parity bits from the recursive systematic convolutional code sequence in order to achieve a predetermined coding rate which is given by a general relation “m/(m+1)” where m=cn−b, c is a constant in accordance with a dominant error event of the recursive systematic convolutional code sequence, n is a natural number, and b=(1, 2, . . . , c−1), and parity bits to be left in the recursive systematic convolutional code sequence are determined according to a point in time k which is give by “k=mj+d” where d is a constant and j is an integer equal to or larger than zero.