Patent ID: RE42627

Claim:
A system for decoding a predetermined message symbol of a plurality of message symbols embedded in an audio signal, comprising: means for receiving an audio signal in which a plurality of message symbols have been incorporated so that the message symbols are inaudible when the audio signal is reproduced audibly, the plurality of message symbols being contained within a predetermined message as a plurality of code symbols, the predetermined message symbol being represented by first and second code symbols incorporated in and displaced in time in the audio signal with at least one code symbol representing a different one of the message symbols being incorporated in the audio signal and positioned in time between the first and second code symbols; means for accumulating a first signal value of the first code symbol representing the predetermined message symbol and a second signal value of the second code symbol representing the predetermined message symbol; and means for examining the accumulated first and second signal values to detect the predetermined message symbol represented by the first and second code symbols.