| 摘要 |
A detector ( 100 ) detects the presence of a watermark in an information signal. The information signal is correlated with an expected watermark (Wi) for each of a plurality of relative positions of the information signal with respect to the watermark to derive a set of correlation results ( 64 ). A metric, such as a mean square value, is calculated for a cluster of the results ( 64 ). The metric is compared with a threshold h which is indicative of the cluster representing the presence of a correlation peak. The metric can be calculated for clusters formed at every position in the results buffer ( 64 ). Alternatively, the metric can be calculated only for a cluster which is identified as being a likely correlation peak.
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