Data decoding apparatus and method utilizing a single channel maximum likelihood decoder

摘要

A data decoding apparatus and method are provided for decoding a reproduction signal in a digital magnetic recording/reproducing apparatus. A Viterbi decoder having a single channel is constructed such that the noise level corresponds to that of an EnPR4 system and the aperture ratio of an eye pattern corresponds to that of a PR(+1, -1) system, thereby improving the efficiency of the Viterbi decoder and allowing state detection by the PR(+1, -1) system. Data can be decoded by a system having a PR4 or EnPR4 channel or selectively by other various systems.