| 摘要 |
An apparatus for controlling the operational status of echo canceling in an echo canceler is disclosed. A digital signal processor (DSP) module (52) is configured to provide two bandlimited filters (66, 68). A CAT filter (66) detects the exclusive presence of a continuity assurance. Test (CAT) tone, and a disable filter (68) detects the exclusive presence of an echo canceling disable tone. Outputs from the DSP module (52) couple to a controller module (64), and a control output from the controller module (64) couples to an echo canceler module (54). The control output causes the echo canceler module (54) either to provide echo canceling or to bypass echo canceling. Upon detection of the CAT tone (106), the control module (64) enables echo canceling (88). After the CAT tone disappears (90), the control module (64) monitors the disable filter (68) to determine whether the disable tone is being transmitted (94). If the disable tone is detected, the control module (64) disables echo canceling (100). After the disable tone disappears (102), the control module (64) monitors the CAT filter (66) to determine whether the CAT tone is being transmitted (106).
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