0883939-A1 is referenced by 11 patents.

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
EP19970907903 19970225
Publication Number
0883939 (A1)
Application Date
February 25, 1997
Publication Date
December 16, 1998
Inventor
Lu Daozheng
US
Moses Donald Wadia
US
Assignee
Nielsen Media Res
US
IPC
H04H 09/00
G10L 11/00
H04H 20/31
G10L 11/00
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