| 摘要 |
A detector (30) is described for detecting a digital signal (Bi<o>) out of an input information signal (Ai) which represents a runlength limited sequence, the runlength having a minimal value m. The detector (30) generates (60, 62) a preliminary binary signal (Bi) out of the input information signal (Ai). A composed sequence of subsequent bits is identified (86) within the preliminary binary signal (Bi) which subsequently includes at least a first neighboring bit of a run of length greater or equal than m+1, one or more further runs of length m and at least a second neighboring bit of a run of length greater or equal than intl. A set of sequences are generated (84, 86). These sequences can be obtained from said composed sequence by changing polarities of binary values within the composed sequence without violating the runlength constraint. The set includes the composed sequence obtained from the preliminary binary signal. A path metric (D) is calculated (94, 96) for two or more sequences of the set, said path metric (D) being the sum of the branch metrics (d) for the path through the trellis corresponding to the sequence of binary values. The sequence from the set which has the highest likelihood of corresponding to the input sequence represented by the input information signal (Ai) is identified (86, 98, 100) on the basis of the path metric.
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