Encoding data onto audio signal with multifrequency sets simultaneously present on signal

摘要

An audio signal is simultaneously encoded with multiple symbols by generating a plurality of code frequency component sets, each set representing a respectively different code symbol and including a plurality of first code frequency components each of which differs in frequency from each other first code frequency component of each of the code frequency component sets. The code frequency components of at least two of the component sets are combined in the audio signal so that the first frequency components of the respective component sets are simultaneously present in the audio signal.