Noise cancellation for wireless audio distribution system
View Patent ↗A wireless audio distribution system may have a wireless transmitter, responsive to a plurality of audio input channels, for transmitting signals carrying the audio, a receiver, responsive to the transmitted signals for selecting one or more of the audio input channels to be reproduced in accordance with local setting selectors at the receiver. Speaker audio channel anti-noise signals can be subtracted from the head audio channel to cancel the noise related to the playing of the speaker audio on the speakers while the headset audio is played on the headset. Analog anti-noise signals can be produced by use of a microphone associated with the headset and later subtracted from the headset audio.
1. A noise canceling wireless audio distribution system, comprising:
a selection switch for selecting a speaker audio channel, from a plurality of audio channels, to be played on a plurality of speakers in a vehicle;
a wireless transmitter for transmitting an uncompressed serial digital bitstream on a single communication channel, the uncompressed serial digital bitstream including at least a subset of the plurality of audio channels combined with digital control codes;
a wireless receiver responsive to the uncompressed serial digital bitstream for selecting, and playing on a headset associated with the wireless receiver, a headset audio channel from the plurality of audio channels; and
a noise cancellation processor in the headset, for canceling noise related to the playing of the speaker audio channel on the speakers while the headset audio channel is played on the headset in accordance with the control codes in the uncompressed serial digital bitstream, by subtracting speaker anti-noise signals related to the wirelessly received speaker audio channel from the headset audio channel being played.
2. The invention of claim 1 wherein operation of the selector switch to select the speaker audio channel causes the speaker audio channel to be identified by the wireless receiver in the serial bitstream.
3. The invention of claim 2 wherein operation of the selector switch to select the speaker audio channel causes the speaker audio channel to be included in the serial bitstream in a known position related to the other audio channels.
4. The invention of claim 1 wherein the noise cancellation processor further comprises: a correction table for modifying the wirelessly received speaker audio channels, in accordance with a path between the headset and at least one of the plurality of speakers, to develop the anti-noise signals.
5. The invention of claim 4 further comprising: at least one microphone associated with the headset for detecting ambient audio.
6. The invention of claim 5 wherein characteristics of the path are applied to the correction table in response to the detected ambient audio.
7. The invention of claim 5 wherein the noise cancellation processor further comprises: a correction table generator for controlling the correction table in accordance with the wirelessly received speaker audio.
8. The invention of claim 5 wherein correction table generator is responsive to ambient audio to produce an analog anti-noise signal to be subtracted from the headset audio channel.
9. The invention of claim 8 further comprising: a digital to analog converter for converting the headset audio channel, after the speaker anti-noise signals have been subtracted therefrom, to analog signals so that the analog anti-noise signals can be subtracted therefrom to produce analog headset audio to be played by the headset.
10. A noise canceling wireless audio distribution system, comprising:
a selection switch configured to select a first audio source from a plurality of audio sources for play by one or more speakers in a vehicle;
a transmitter connected to the plurality of audio sources, wherein the transmitter is configured to wirelessly transmit an uncompressed serial digital bitstream on a single channel, the uncompressed serial digital bitstream comprising:
an audio signal from the first audio source;
an audio signal from at least one of the other of the plurality of audio sources; and
digital control codes;
a wireless receiver responsive to the uncompressed serial digital bitstream, wherein the wireless receiver is configured to select, from the uncompressed serial digital bitstream, the audio signal from the at least one of the other of the plurality of audio sources for play by a headset associated with the wireless receiver; and
a noise cancellation processor in the headset, wherein the noise cancellation processor is configured to:
generate an anti-noise signal based on the audio signal from the first audio source; and
subtract the anti-noise signal from the audio signal selected by the wireless receiver to cancel noise associated with the play of the first audio source by the one or more speakers while the audio signal selected by the wireless receiver is played on the headset in accordance with the control codes in the uncompressed serial digital bitstream.