06035177 is referenced by 198 patents and cites 26 patents.

A communication system for simultaneously 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 spectrum 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
8/607097
Publication Number
6035177
Application Date
February 26, 1996
Publication Date
March 7, 2000
Inventor
Daozheng Lu
Dunedin
FL, US
Donald Wadia Moses
Eagan
MN, US
Agent
Haynes & Boone L
Assignee
Nielsen Media Research
FL, US
Donald W Moses
FL, US
IPC
H04N 7/10
H04N 7/00
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