Freescale Semiconductor,inc.

Hongyang Deng

Roman A Dyba

Wen Wu Su

Perry P He

Brad L Zwernemann

A technique for detecting in-band signaling tones in a communication system includes performing a first adaptation of an adaptive filter of an echo canceller in response to detection of a far-end harmonic signal. In this case, the adaptive filter provides an echo estimation signal. The technique also includes subtracting the echo estimation signal from a near-end signal that includes one or more in-band signaling tones to provide an error signal. The technique further includes detecting, using a tone detector, the one or more in-band signaling tones in the error signal.

Techniques for implementing adaptation control of an echo canceller to facilitate detection of in-band signals

A technique for updating filter coefficients of an adaptive filter includes filtering a signal with an adaptive filter, whose filter coefficients are grouped into filter blocks. In this case a number of the filter blocks is less than or equal to a number of the filter coefficients. During each update period, the filter coefficients for less than all of the filter blocks are updated based on a network echo path impulse response.

Techniques for updating filter coefficients of an adaptive filter

In one or more embodiments, an echo reduction system can include multiple adaptive filters operable to provide estimated echo replicas based on received signal information coupled to respective multiple adders that can combine a send signal and outputs of the respective adaptive filters and can provide respective output combinations to a filter selector. The filter selector can select from the outputs of the adders and provide a selected output as output for the echo reduction system. In one or more embodiments, the filter selector can control signal processing of the filters by providing control signal to the adaptive filters, where the control signals can indicate to ones of the adaptive filters to pause or continue signal processing. In one or more embodiments, the echo reduction system can include at least one delay unit that can delay receive signal information to at least one of the adaptive filters.

Time domain adaptive filter bank for network echo reduction or cancellation

Methods and corresponding systems in an adaptive filter include calculating a signal estimator output using filter coefficients, and calculating an error signal. Next, a coefficient threshold is determined. Thereafter, for each filter coefficient, a first step size is assigned to filter coefficients with a magnitude less than the coefficient threshold, and a second step size is assigned to filter coefficients with a magnitude greater than or equal to the coefficient threshold. Finally, the filter coefficients are updated using the first and second step sizes and the error signal. The coefficient threshold can be selected as the average of the magnitudes of the filter coefficients. Alternatively, the coefficient threshold can be selected as the Mth largest of the filter coefficients ranked in order of magnitude. In one embodiment, the first step size can be less than one and the second step size can be greater than one.

Adaptive filter for use in echo reduction

In a data processing system, a method includes receiving samples of a send path input signal (Sin) and samples of a receive path input signal (Rin); in response to receiving each sample of the send path input signal, providing a double-talk indicator to indicate whether or not double-talk has been detected; using the double-talk indicator to determine a double-talk density within a predetermined number of samples of the send path input signal or the receive path input signal; and using the double-talk density to provide a heavy double-talk indicator which indicates whether or not heavy double-talk has been detected. In response to the heavy double-talk indicator indicating that heavy double-talk has been detected, a heavy double-talk mode may be entered.

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Austin, TX, United States of America

Hongyang Deng