Adaptive filtering system
AssigneeHarman Becker Automotive Systems GmbH
InventorMarkus Christoph
Life of this patent
Estimating the term…
Abstract
An audio system with at least one audio channel may include a digital audio processor in which at least one digital filter is implemented for each channel. The digital filter of each channel may include: an analysis filter bank configured to receive a broad-band input audio signal and divide the input audio signal into a plurality of sub-bands, a sub-band filter for each sub-band. and a synthesis filter bank configured to receive the filtered sub-band signals and combine them for providing a broad-band output audio signal. A delay is associated with each sub-band signal, the delay of one of the sub-band signals being applied to the broad-band input audio signal upstream of the analysis filter bank and the residual delays being applied to the remaining sub-band signals downstream of the analysis filter bank.
Claims20
An audio system with at least one audio output channel comprising:
- a digital audio processor in which at least one digital filter is implemented for each of a plurality of audio channels;
- the digital filter of each of the audio channels comprises:
- an analysis filter bank configured to receive an input audio signal and divide the input audio signal into a plurality of sub-bands as sub-band signals having equal bandwidths, a spectra of the sub-band signals constituting a spectrum to of the input audio signal;
- a sub-band filter for each sub-band, the sub-band filter for each sub-band configured to provide respective filtered sub-band signals;
- and
- a synthesis filter bank configured to receive and combine the filtered sub-band signals to provide a broad-band output audio signal;
- where a delay is associated with each of the respective sub-band signals, the delay of one of the sub-band signals being applied to the input audio signal before division by the analysis filter bank, and residual delays being applied to at least some of the sub-band signals divided by the analysis filter bank.
A method for filtering at least one audio signal provided in at least one audio output channel of an audio system;
- the method comprises:
- receiving an input audio signal having a spectrum lying within a frequency band;
- dividing the frequency band of the input audio signal into a plurality of sub-bands to provide sub-band signals, the spectra of the sub-band signals comprising the spectrum of the input audio signal;
- filtering each of the sub-band signals using a respective filter for each sub-band;
- combining the filtered sub-band signals to provide a broad-band output audio signal;
- associating a delay with each of the sub-bands;
- applying the delay associated with one of the sub-bands to the input audio signal before dividing the frequency band;
- and
- applying residual delays to sub-band signals of respective sub bands other than the one of the sub-bands.
An audio system comprising:
- a processor;
- a filter module executed by the processor to receive and process an audio input signal,
- the audio input signal divided into a plurality of sub-band signals by execution of the filter module with the processor;
- each of the sub-band signals associated with a respective sub-band delay and a respective sub-band filter;
- the filter module further executed by the processor to apply a first sub-band delay of a respective first sub-band signal to the audio input signal prior to division of the audio input signal into the sub-band signals;
- the filter module executed by the processor to apply the respective associated sub-band delay to each of the plurality of sub-band signals except the first sub-band signal, to which the first sub-band delay is not applied;
- and
- the filter module executed by the processor to filter each of the sub-band signals with the respective associated sub-band filter, and re-combine the filtered sub-band signals to form an audio output signal.
Dependencies are inferred from the claim text.