1. A method of extracting a watermark from watermarked data comprising the steps of: receiving watermarked data from subregions of watermarked data; spectrum normalizing the watermarked data from each subregion to generate normalized signals, where said spectrum normalizing comprises dividing each frequency coefficient in the watermarked data by a local average power of the frequency coefficients; correlating the normalized signals with predetermined PN sequences corresponding to predetermined symbols to provide correlated signals for each predetermined PN sequence in each subregion; deciding which correlated signal is most likely a current symbol in each subregion for providing an extracted symbol stream; error correcting the extracted symbol stream; and extracting a sequence of most likely current symbols corresponding to the watermark.