Patent ID: 7111225

Claim:
A Viterbi bit detection method for detecting the bit values of bits of a channel data stream stored on a record carrier along an N-dimensional channel tube, N being at least two, of at least two bit rows one-dimensionally evolving along a first direction and being aligned with each other along at least a second of N−1 other directions, said first direction together with said N−1 other directions constituting an N-dimensional lattice of bit positions, said Viterbi bit detection method comprising the steps of: applying a row-based one-dimensional Viterbi bit detection method independent for each of the bit rows of said channel tube; calculating branch metrics for all possible state transitions in a Viterbi trellis of a one-dimensional row-based Viterbi detector, said transitions representing a number of subsequent bits in said bit row, said bits being the central-row bits of a cluster of the N-dimensional lattice of bits, said calculating being based on the difference of the received HF signal value with respect to a reference level, wherein said reference level depends on all bits of said cluster, said cluster comprising, in addition to the central-row bits, a number of primary neighboring bits in each of a number of neighboring bit rows on each side along said N−1 other directions of said central bit row along which the one-dimensional Viterbi bit detection method is applied, and wherein preliminary bit decisions for the primary neighboring bits in the neighboring bit rows are used for determining the reference level to be used for calculating said branch metrics; and selecting the bit value for the central bit of said cluster of the N-dimensional lattice of bits, corresponding with said received HF signal value, based on the calculated branch metrics.