| 摘要 |
A speaker-phone that is operable to perform system change detection, double-talk detection and if desired, optimal step-size control. The invention differentiates between system change and double-talk and is operable to these two situations differently. The invention does not rely solely on the energy measurements that are employed by conventional speaker-phones. Highly reliable system change detection is offered when compared to conventional speaker-phones. The direction and the amplitude of the system change is measured with very good detection probability in the invention. For double-talk detection, the invention does not rely on assumptions that the far-end echoes are of lower amplitude that the near-end signal in performing double-talk detection. The invention performs double-talk detection within a large diversity of echo-paths and background noise levels. A designer may tune the speaker-phone system to ensure proper double-talk detection near low levels of the near-end signal. The step-size optimization control is performed in response to both the system change detection and the double-talk detection. If desired, no step-size optimization control need be performed at all. In embodiments where the certain design budgets allow, a backup of the echo canceller is employed. This allows the speaker-phone system to make mistakes without losing the echo canceller gain if an improper decision is made. The invention allows for designer control over parameters such as thresholds, constants and time constants, depending on what numerical resolution is used in the calculations and what preferences one has for items such as sensitivity to double-talk and system change.
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