Patent ID: 7430705

Claim:
A data recording and reproducing system that adds a first error correcting code to input data to generate a first code block, encodes the first code block with a second error correcting code to generate a second code block, interleaves the second code block to generate a recording block, and records and reproduces the recording block via a partial response channel including a recording medium, the system comprising: an iterative decoder that iteratively decodes an output signal from the partial response channel, and decodes the second code block; a preliminary decision and reliability detection unit that preliminarily determines decoded data and determines reliability of the decoded data, based on likelihood information obtained during iterative decoding in the iterative decoder; and a first error correcting code decoder that decodes the first error correcting code, the preliminary decision and reliability detection unit supplying the preliminarily determined decoded data and reliability information of the decoded data to the first error correcting code decoder, wherein the preliminary decision and reliability detection unit makes a preliminary hard decision based on the likelihood information obtained during iterative decoding, wherein the iterative decoder comprises a first a posteriori probability decoder that performs a posteriori probability decoding on the partial response channel, and a second a posteriori probability decoder that decodes the second code block, and the preliminary decision and reliability detection unit makes a preliminary hard decision based on the likelihood information obtained during iterative decoding that is supplied from the first a posteriori probability decoder.