A communication system for simulataneously transmitting ancillary codes and audio signals via a conventional audio communications channel using perceptual coding techniques is disclosed. An encoder monitors an audio channel to detect 'opportunities' to insert an ancillary code such that the inserted signals are masked by the audio signal, as defined by the 'perceptual entropy envelope' of the audio signal. An ancillary code containing, for example, an ID or serial number, is encoded as one or more whitened spread stpectrum signals and/or a narrowband FSK ancillary code and transmitted at a time, frequency and/or level such that the data signal is masked by the audio signal. A decoder at a receiving location recovers the encoded ID or serial number.

Title
Simultaneous transmission of ancillary and audio signals by means of perceptual coding
Application Number
PCT/US1997/003054
Publication Number
1997/031440
Application Date
February 25, 1997
Publication Date
August 28, 1997
Inventor
Lu Daozheng
Moses Donald Wadia
Agent
JOIKE Trevor B
Assignee
Nielsen Media Research
IPC
H04H 20/31
G10L 11/00
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