Configuring Echo Adjustment Function - 3Com MSR 50 Series Configuration Manual

2262 C 131: V
HAPTER OICE
Configuring Echo
Adjustment Function
S L C
UBSCRIBER INE ONFIGURATION
Task
"Configuring Echo Adjustment Function" on page
2262
"Configuring Gain Adjustment Function" on page
2263
"Configuring Time Adjustment Function" on page
2263
"Configuring Comfort Noise Function" on page 2264
Echo adjustment
The voice of a user is repeated and sent back to the handset, resulting in echoes.
This is because analog signals leak into the receiving path of the user. The echo
adjustment function provided by the VoIP gateway can cancel echoes to some
extent.
You can cancel echoes in three ways:
1 Adjust echo duration
Table 77 Adjust echo duration
Symptom
A user hears some
echoes in
conversation.
2 Adjust echo cancellation parameters
Table 78 Adjust echo cancellation parameters
Symptom
A user hears echoes or loud
background noises from the
peer when speaking.
There are loud environment
noises.
A user hears echoes when
speaking.
There are echoes when both
parties speak at the same
time.
3 Enable the nonlinearity function of echo cancellation
The nonlinearity function 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.
Reason
The echo duration is so long that the
convergence time of echo cancellation on the
network becomes longer.
The echo duration is so short that
long-duration echoes are not completely
cancelled.
Parameters adjusted
Speed up the convergence of
comfortable noise amplitudes
Increase the maximum
amplitude of comfortable
noises.
Enlarge the control factor of
mixed proportion of noises.
Enlarge the judgment
threshold for bidirectional
conversation.
Remarks
Optional
Optional
Optional
Optional
Adjustment method
Shorten echo duration
Prolong echo duration
Effect
Too fast convergence may
makes noises uncomfortable.
Too large amplitude may
make noises uncomfortable.
Too high a control factor
leads to audio discontinuity.
Too high a judgment
threshold slows down the
convergence of the filter
factor.