The optical disk apparatus is provided with a Viterbi decoder and an expected value correction circuit. The branch metric operation unit calculates first, second and third errors between sampling data and expected values, and outputs them to the expected value correction circuit. The expected value correction...http://www.google.com/patents/US20030002419?utm_source=gb-gplus-sharePatent US20030002419 - Optical disk apparatus permitting high-precision Viterbi decoding
