Dsc Communications Corporation

Terrence G Sopira

Kishan Shenoi

Paul P Yang

An integrated echo canceling multiplexor is provided which comprises an echo canceler for receiving DS1 signals for canceling echo in the DS1 signal and producing an echo-free digital logic signal. A first performance monitor is coupled to the echo canceler for receiving the echo-free digital logic signal and determining the quality of the signal. A multiplexor-demultiplexor is further coupled to the echo canceler for receiving the echo-free digital logic signal and producing a DS3 signal. Additionally, a second performance monitor is coupled to the multiplexor-demultiplexor and receives the DS3 signal and determines the quality of the signal.

Integrated echo canceling multiplexor

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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Terrence G Sopira