Abstract: An embodiment of the present invention includes an adaptive predictor, a system white noise generator, and a background noise estimator. The adaptive predictor estimates adaptive weights of autoregressive (AR) model of background noise as background samples in an echo canceler. The adaptive predictor generates adaptive error. The system white noise generator generates a white noise using the adaptive error. The noise background estimator estimates the background noise using the white noise and the estimated adaptive weights.

Abstract: The present invention is an echo canceller for sparse channels in an echo channel. The echo channel receives a far-end input and a near-end input. An enable generator asserts a sparse update enable in response to detecting at least one of the double talk condition and an impulse response change. A main weight updater transfers shadow weights of the shadow filter to N sets of sparse weights in N sparse filters of the main filter according to the sparse update enable. A sparse main filter filters the far-end input non-adaptively to generate a main output. A long shadow filter filters the far-end input adaptively to generate a shadow output and to estimate delays of peaks of the sparse weights in the main filter.

Abstract: Disclosed is an integrated tone detection processor for discriminating between tone and voice signals and determining the tones. The tone detection processor performs Automatic Gain Control (AGC) to normalize the power of the tone or voice signal. Further, the energy of the tone or voice signals are determined at specific frequencies utilizing a Goertzel Filter process. The tone detection processor determines whether or not a tone is present, and if a tone exists, determines the type of tone. Based upon determining the two maximum energy levels of the Goertzel filtered tone, whether the tone is a single tone, dual tone, silence, or other (e.g. speech) can be discriminated. The tone can then be identified by a user-defined dictionary of tones. Based upon various ON and OFF cadence checks in combination with the use of TONE ON and TONE OFF counters, tones can be declared.

Abstract: A first adaptive filter having a first filter length estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The echo channel has a plurality of sparse multi-path channels. A delay estimator determines a plurality of delays in the echo channel using the estimated channel weight vector. A second adaptive filter estimates a plurality of short weight vectors using the AP update and the plurality of delays. The short weight vectors correspond to the sparse multi-path channels. Each of the short weight vectors has a short filter length.

Abstract: An embodiment of the present invention includes an adaptive predictor, a system white noise generator, and a background noise estimator. The adaptive predictor estimates adaptive weights of autoregressive (AR) model of background noise as background samples in an echo canceler. The adaptive predictor generates adaptive error. The system white noise generator generates a white noise using the adaptive error. The noise background estimator estimates the background noise using the white noise and the estimated adaptive weights.

Abstract: The present invention is an echo canceller for sparse channels in an echo channel. The echo channel receives a far-end input and a near-end input. An enable generator asserts a sparse update enable in response to detecting at least one of the double talk condition and an impulse response change. A main weight updater transfers shadow weights of the shadow filter to N sets of sparse weights in N sparse filters of the main filter according to the sparse update enable. A sparse main filter filters the far-end input non-adaptively to generate a main output. A long shadow filter filters the far-end input adaptively to generate a shadow output and to estimate delays of peaks of the sparse weights in the main filter.

Abstract: A network echo canceller for integrated telecommunications processing. The network echo canceller processes echoes in multiple communication channels over a packet network. The network echo canceller adapts a least means squared finite impulse response filter to each communication channel in order to estimate an echo therein. The echo estimation is subtracted from signals that are being sent over each communication channel. The echo canceller includes a residual error suppressor to suppress non-linear sources of echo when desired. The echo canceller includes a double talk detector to inhibit filter adaptation during double talk. The network echo canceller is programmable into a digital signal processor and can be flexibly controlled through messaging.

Abstract: An adaptive filter estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The channel weight vector has first and second lengths when the adaptive filter operates in a first adaptation mode and a second adaptation mode, respectively. A delay estimator determines a delay in the echo channel using the adaptive filter in the first adaptation mode.

Abstract: The invention provides a novel scheme for performing echo cancellation in the presence of double-talk and near-end channel impulse response changes. In one embodiment of the invention, a non-adaptive main filter is updated with the filtering weights of an adaptive shadow filter if the shadow filter cancels near-end echo in a first signal to a greater extent than the main filter. However, if double-talk is present in the first signal, then the non-adaptive filter is not updated. According to one embodiment of the invention, distinguishing between double-talk and channel impulse response changes is accomplished by maintaining extra taps for the main and shadow filters, in addition to taps employed by the main and shadow filters for echo canceling. The corresponding filtering algorithm weights for the additional taps of the main and shadow filters are compared to detect the onset of double-talk and/or channel impulse response changes.

Abstract: Disclosed is an integrated voice activation detector for detecting whether voice is present. In one embodiment, the integrated voice activation detector includes a semiconductor integrated circuit having at least one signal processing unit to perform voice detection and a storage device to store signal processing instructions for execution by the at least one signal processing unit to: detect whether noise is present to determine whether a noise flag should be set, detect a predetermined number of zero crossings to determine whether a zero crossing flag should be set, detect whether a threshold amount of energy is present to determine whether an energy flag should be set, and detect whether instantaneous energy is present to determine whether an instantaneous energy flag should be set. Utilizing a combination of the noise, zero crossing, energy, and instantaneous energy flags the integrated voice activation detector determines whether voice is present.

Abstract: A first adaptive filter having a first filter length estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The echo channel has a plurality of sparse multi-path channels. A delay estimator determines a plurality of delays in the echo channel using the estimated channel weight vector. A second adaptive filter estimates a plurality of short weight vectors using the AP update and the plurality of delays. The short weight vectors correspond to the sparse multi-path channels. Each of the short weight vectors has a short filter length.

Abstract: Disclosed is an integrated tone detection processor for discriminating between tone and voice signals and determining the tones. The tone detection processor performs Automatic Gain Control (AGC) to normalize the power of the tone or voice signal. Further, the energy of the tone or voice signals are determined at specific frequencies utilizing a Goertzel Filter process. The tone detection processor determines whether or not a tone is present, and if a tone exists, determines the type of tone. Based upon determining the two maximum energy levels of the Goertzel filtered tone, whether the tone is a single tone, dual tone, silence, or other (e.g. speech) can be discriminated. The tone can then be identified by a user-defined dictionary of tones. Based upon various ON and OFF cadence checks in combination with the use of TONE ON and TONE OFF counters, tones can be declared.

Abstract: An adaptive filter estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The channel weight vector has first and second lengths when the adaptive filter operates in a first adaptation mode and a second adaptation mode, respectively. A delay estimator determines a delay in the echo channel using the adaptive filter in the first adaptation mode.

Abstract: A network echo canceller for integrated telecommunications processing. The network echo canceller processes echoes in multiple communication channels over a packet network. The network echo canceller adapts a least means squared finite impulse response filter to each communication channel in order to estimate an echo therein. The echo estimation is subtracted from signals that are being sent over each communication channel. The echo canceller includes a residual error suppressor to suppress non-linear sources of echo when desired. The echo canceller includes a double talk detector to inhibit filter adaptation during double talk. The network echo canceller is programmable into a digital signal processor and can be flexibly controlled through messaging.