04868881 is referenced by 38 patents and cites 11 patents.

To improve the fidelity of reproduction of automobile radios during conditions of extraneous in the passenger compartment, noise signals are derived, for example from a microphone installed in the engine compartment of the vehicle. The audio program signals are conducted through a multichannel equalizer; the program audio signals and the noise signals are separated into a plurality of frequency bands, for example three bands, the envelope of which are demodulated and the derived demodulation signals are instantaneously compared to then control the transfer characteristics of the respective bands of the equalizer in accordance with the derived comparison between the respective bands of the noise and program signals. Preferably, amplitude, change of transfer amplitude and rate of change is controlled by weighting the comparison signals and the rate of change thereof in relation to the frequency bands and the extent of change of the signals.

Title
Method and system of background noise suppression in an audio circuit particularly for car radios
Application Number
7/239783
Publication Number
4868881
Application Date
September 1, 1988
Publication Date
September 19, 1989
Inventor
Klaus Deuter
Freising
DE
Eberhard Zwicker
Icking
DE
Agent
Frishauf Holtz Goodman & Woodward
Assignee
Blaupunkt Werke
DE
IPC
H03G 3/20
H03G 3/00
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