Patent ID: 8259928

Claim:
A method of processing a digital signal for enhancing audio echo cancellation in a two-way communication system, wherein the audio echo cancellation predicts echo from a rendered signal in a captured signal based on an adaptive filter, the method comprising: calculating a relative offset for aligning a sample of the rendered signal with a sample of the captured signal; applying a filter to effect smoothing of the relative offset; adjusting the relative offset of a current signal sample if a difference between it and an adjusted relative offset of a preceding sample exceeds a threshold value, wherein the threshold value is selected so that the adjusted relative offset changes over time in a single direction; predicting an echo with an adaptive filter by using the adjusted relative offset of the current signal sample to align the rendered signal with the captured signal; and subtracting the predicted echo from a signal to be transmitted to a remote end device, wherein, if a difference between the relative offset of the current signal sample and the adjusted relative offset of the preceding sample exceeds the threshold value, adjusting the relative offset of the current signal sample by adding the threshold value to or subtracting the threshold value from the relative offset of the current signal sample so that a difference between the relative offset and the adjusted relative offset of the current signal sample is less than the threshold value.