| 摘要 |
An apparatus 330 comprises a correlation processor 333 operable in combination with a data sequence processor 332 to form a correlation sequence (Figure 9) and a data processor 334 operable under control of the correlation processor 333 to correlate information material data symbols (wavelet coefficients in store 331) with which modulated data have been combined, with the correlated sequence, to form a correlation output signal representing the correlation between the information material data symbols and the correlation data sequence, recovering embedded data from the correlation output signal. The correlation sequence comprises a plurality of predetermined data sequence versions, each version representing a possible form of the predetermined data sequence for recovering the embedded data symbols from the modulated data and may have a plurality of predetermined data sequence shifted versions, shifted with respect to one another. The embedded data may be detectable from the transform domain data symbols in spite of a relative shift of the transform domain data symbols. Alternatively, the predetermined data sequence versions may be a set of different predetermined data sequences, one of which has been used to generate the modulated data. |
