Configuring echo cancellation
Echo cancellation
An echo is the audible leak-through of your own voice into your own receive path. When the voice of a user leaks into the receive path of the user, it is an echo. To cancel echoes, adjust the echo cancellation function in the VoIP gateway as follows:
Adjust echo duration
Table 2: Adjust echo duration
Symptom | Reason | Adjustment method |
|---|---|---|
A user hears a delayed copy of the original voice of the user. | The echo duration is so long that the convergence time of echo cancellation on the network becomes longer. | Shorten echo duration |
The echo duration is so short that long-duration echoes are not completely cancelled. | Prolong echo duration |
Adjust echo cancellation parameters
Table 3: Adjust echo cancellation parameters
Symptom | Parameters adjusted | Effect |
|---|---|---|
A user hears echoes or loud background noises from the peer when speaking. | Speed up the convergence of comfortable noise amplitudes | Too fast convergence might make noises uncomfortable. |
There are loud environment noises. | Increase the maximum amplitude of comfortable noises. | Too large amplitude might make noises uncomfortable. |
A user hears echoes when speaking. | Enlarge the control factor of mixed proportion of noises. | Too high a control factor leads to audio discontinuity. |
There are echoes when both parties speak at the same time. | Enlarge the judgment threshold for bidirectional conversation. | Too high a judgment threshold slows down the convergence of the filter factor. |
Enable the nonlinear function of echo cancellation
The nonlinear function of echo cancellation, also known as residual echo suppression, means the removal of residual echoes after echo cancellation when the user at the local end does not speak.
Configuration procedure
To configure the echo adjustment function:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter voice view. | voice-setup | N/A |
3. Configure echo cancellation parameters. | echo-canceller parameter { convergence-rate value | max-amplitude value | mix-proportion-ratio value | talk-threshold value } | Optional. By default, the convergence rate of comfort noise amplitude is 0, the maximum amplitude of comfort noise is 256, the comfort noise mixture proportion control factor is 100, and the threshold of two-way talk is 1. |
4. Exit voice view. | quit | N/A |
5. Enter voice subscriber line view. | subscriber-line line-number | N/A |
6. Enable the echo cancellation function. | echo-canceller enable | Enabled by default. |
7. Configure echo duration. | echo-canceller tail-length milliseconds | Optional. The default is 0 milliseconds. |
8. Enable the nonlinear function of echo cancellation. | nlp-on | Optional. Enabled by default. This command is available only after the echo-canceller enable command is executed. |