05161210 is referenced by 254 patents and cites 4 patents.

The audio signal is divided into frequency sub-bands, the sub-band samples are quantized according to a predetermined quantizing criterion, and the quantized samples in one or more sub-bands are summed with samples of the auxiliary signal in such sub-bands, the auxiliary signal sample in a sub-band having a maximum amplitude less than half the quantization step used in such sub-band. The combined signal, covering the entire frequency band of the audio signal, can be transmitted or recorded on a record carrier. Upon audio reproduction at a receiver only the audio signal will be audible, the auxiliary signal being masked due to the psychoacoustic characteristics of the human auditory system which are unresponsive to low-level noise in the presence of high amplitude sound. The receiver includes a decoder which analyzes the combined signal into the original frequency sub-bands and re-quantizes the sub-band signals using the same quantizing criterion as at the coder. The auxiliary signal is reconstructed by subtracting the quantized signal sample in each sub-band from the non-quantized signal sample therein and combining the non-quantized sub-band signal sample. The auxiliary signal may be a copy inhibit code which serves to inhibit a recorder from recording the audio signal, thus protecting against unauthorized copying.

Title
Coder for incorporating an auxiliary information signal in a digital audio signal, decoder for recovering such signals from the combined signal, and record carrier having such combined signal recorded thereon
Application Number
7/433631
Publication Number
5161210
Application Date
November 8, 1989
Publication Date
November 3, 1992
Inventor
Raymond N J Veldhuis
Eindhoven
NL
Leon M Van De Kerkhof
Eindhoven
NL
Abraham Hoogendoorn
Eindhoven
NL
Willem F Druyvesteyn
Eindhoven
NL
Agent
Leroy Eason
Assignee
U S Philips Corporation
NY, US
IPC
G10L 7/04
G10L 9/00
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