Freescale Semiconductor,inc.

Perry P He

Roman A Dyba

Lucio F C Pessoa

Roger Alan Smith

Brad L Zwernemann

Ahsan Aziz

Hongyang Deng

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

A technique of operating a communication device includes dividing a frequency band associated with a background noise signal into respective sub-bands. Respective individual level estimates for each of the respective sub-bands are then determined. A total level estimate for the background noise signal is determined. Finally, a comfort noise signal (whose characteristics are based on the respective individual level estimates and the total level estimate) is provided.

Techniques for comfort noise generation in a communication system

Methods and corresponding systems for reducing an echo signal include assigning a subsegment delay to each of a plurality of subsegment adaptive filters. A send signal and a delayed receive signal are coupled to each of the subsegment adaptive filters, wherein the delayed receive signal is delayed according to a respective subsegment delay. A set of filter coefficients in each of the subsegment adaptive filters are adapted, in parallel, to correspond to a respective subsegment impulse response of a connected system. Each set of filter coefficients is analyzed to produce a pure delay, and the pure delay is used to delay the receive signal for a main adaptive filter. An echo signal replica is produced using the main adaptive filter and an error signal. The echo signal replica is subtracted from the send signal to produce the error signal.

Estimating delay of an echo path in a communication system

Methods and corresponding systems for allocating processing resources for a number of instances (N) of a software component include determining an average processing cost (&#x3bc;) and a variance (&#x3c3;) for the software component. Then a processing cost for the software component is estimated as a function of N, the average processing cost (&#x3bc;), and the variance (&#x3c3;), and processing resources are allocated in response to the estimated processing cost. The software component can be partitioned into a number of blocks (L), wherein the L blocks include a required block and one or more optional blocks. In some embodiments in response to a total estimated processing cost exceeding an available processing value, selected optional blocks can be disabled to reduce the total estimated processing cost to a value equal to or less than the available processing value. The optional blocks can be prioritized and disabled in order of priority.

Allocating processing resources for multiple instances of a software component

A method and apparatus for dynamically inserting gain in an adaptive filter is taught. This selective insertion of gain may be used to allow an adaptive filter to converge more quickly and/or to overcome inherent limitations of the adaptive filter. An echo canceller (e.g.andin FIG.) is just one possible use for an adaptive filter having a shorter convergence time. However, virtually all uses of an adaptive filter can benefit from a shorter convergence time and/or improved filtering performance.

Method and apparatus for dynamically inserting gain in an adaptive filter system

A communication system having an echo canceller is disclosed. One embodiment of the echo canceller includes an adaptive filter used to provide an estimate of reflected echo which is removed from the send signal. The echo canceller may also include a near-end talker signal detector which may be used to prevent the adaptive filter from adapting when a near-end talker signal is present. The echo canceller may also include a nonlinear processor used to further reduce any residual echo and to preserve background noise. The echo canceller may also include a monitor and control unit which may be used to monitor the filter coefficients and gain of the adaptive filter to maintain stability of the echo canceller, estimate pure delay, detect a tone, and inject a training signal. The echo canceller may also include a nonadaptive filter used to reduce the length of the adaptive filter.

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Austin, TX, United States of America

Perry P He