Patent ID: 8625775
Filing Date: 2014-01-07
Classification: H04M

Abstract:
1. A method for performing adaptive signal conditioning, comprising: determining an initial value for a step size used in an adaptive filter algorithm based on: a background noise signal power level relative to a power level of a received signal; and a power level of an echo estimate relative to an output of an echo canceller; and adjusting the step size value based on the detection of large fast fourier transform dues at one, or more, disturbing-signal frequencies: wherein the method step of adjusting the step size value based on the detection of large fast courier transform values at one, or more, disturbing-signal frequencies includes: processing a predetermined number of signal samples acquired during a short sampling period to compute a receive fast fowler transform vector; processing the corresponding estimated echo samples to compute a reduced echo fast fourier transform vector; computing the product of the receive fast fourier transform vector and the reduced fast fourier transform vector to obtain a fast fourier transform product vector; averaging multiple fourier transform product vectors from corresponding multiple sampling periods over a long sampling period into a average fourier transform product vector; updating the average fourier transform product vector with a fourier transform product vector processed during a current iteration of the short sampling period; determining a plurality of deviations, each of the plurality of deviations determined between the fourier transform product vector determined during the most recent short sampling period and the most recently updated average fourier transform product vector for one of a predetermined frequencies; determining an average of a plurality of the deviations for which the fourier transform product vector exceeds the most recently updated average fourier transform product vector; and reducing the step-size if the average of the plurality of deviations exceeds a predetermined threshold.