Patent ID: 8199907

Claim:
An echo canceler for removing an echo of a far-end input signal from a near-end input signal by adaptive filtering, the echo canceler comprising: a voice detector for detecting an active state and a silent state of the far-end input signal; a first adaptive filter for filtering the far-end input signal by using first coefficients and adapting the first coefficients according to the far-end input signal and the near-end input signal, the first coefficients being adapted only when the voice detector detects the active state; a second adaptive filter for filtering a simulated far-end input signal by using second coefficients and adapting the second coefficients according to the simulated far-end input signal and a simulated near-end input signal, the second coefficients being adapted only when the voice detector detects the silent state; a data selector for simultaneously sampling the far-end input signal and the near-end input signal over periods of a predetermined length, each of the periods including an interval in which the voice detector detects the active state, to generate a plurality of processable signals, each processable signal including a series of samples; a simulated signal generator for generating the simulated far-end input signal and the simulated near-end input signal from the processable signals by combining samples in corresponding positions in different ones of the processable signals; an adaptive mode controller for starting and stopping adaptation of the first and second coefficients in the first and second adaptive filters and, when starting the adaptation of the first coefficients after a period during which the second coefficients were adapted and the first coefficients were not adapted, using the second coefficients as initial values of the first coefficients; and a self-cancellation detector for deciding when self-cancellation has occurred by deciding whether combining the samples in the corresponding positions in the different ones of the processable signals has caused the combined samples to cancel each other out, and disabling use of at least parts of the simulated far-end signal and the simulated near-end signal for adaptation of the second coefficients in the second adaptive filter when self-cancellation has occurred.