摘要:
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.
摘要:
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.
摘要:
A system includes receive and send inputs, an adaptive filter, a combiner, a non-linear processor, and a tone detector. The receive input receives a first signal having first voice and first tone information. The send input receives a second signal having echo information, second tone information, and second voice information. The adaptive filter has an input coupled to the receive input, and an output. The combiner has a first input coupled to the send input, a second input coupled to the output of the adaptive filter, and an output providing an intermediate signal. The nonlinear processor has an input coupled to the output of the combiner and an output for providing an output signal for obtaining the second voice. The tone detector is coupled to the output of the combiner and detects the second tone in the intermediate signal prior to the intermediate signal being processed by the nonlinear processor.
摘要:
In one embodiment, a tone event detector first determines whether the presence of a tone is indicated on the input signal, and then, based on this determination, selectively determines whether a tone has been detected on the input signal. For example, in one embodiment, tone detection is performed only when the presence of a tone is first indicated, such that if the presence of a tone is not indicated, tone detection need not be performed. This may help reduce complexity of a tone event detector since a simplified method may be used to indicate the presence of a tone, and the more complex algorithms for tone detection may be enabled only when needed. Also, in one embodiment, detection of a tone includes generating one or more tone characteristics corresponding to the detected tone which may then be used to determine whether the detected tone corresponds to a valid tone event.
摘要:
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.
摘要:
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.
摘要:
A method, computer program product, and data processing system for performing automated optimization of a control processing flow containing Boolean conditional expressions is disclosed. Each conditional expression is profiled using a representative set of test vectors to determine the probabilities of individual conditions and combinations of conditions in the expression. Next, the expression is restructured or reordered, including selective computation of subexpressions, based on the probability information, so as to maximize the probability of a short-circuit termination of evaluation of the expression and/or to minimize the statistical execution time of the expression. This process is performed for all Boolean conditional expressions related to the control processing flow.