38
5.6.2 Acoustic echo canceller
One of the main disadvantages of “hands free” communica
on the remote terminal. With traditional communications systems, this echo has always
occurred on the transition from 2 to 4 wires, but it did not cause any problems for the speaker as
there was no delay. To the cont
With the introduction of voice communications over switched networks, and subsequently over
IP networks, this delay has increased considerably, even going so far as to hinder proper
communication between both points.
the speaker does not hear him/herself speak.
advantages of traditional communications
heard at the other end.
It is worth noting that the acoustic echo cancellers that are
for a “clean” type of environment, i.e. when the speaker talks, the
his/her voice, with minimal distortion, plus the voices speaking on the other end.
the speaker’s voice becomes too distorted (either due to the location of the microphone and
speaker or the volume being too high), the adaptive can
properly and introduces noises, especially at the beginning and end of sentences.
Given that IPefonos are designed to work in very diverse environments, they incorporate a
variety of echo cancellation mechanisms, so they c
offered by the environment. The different alternatives that are available are listed below.
Naturally, before configuring the echo canceller, it is essential to set the conversation volume
that you are going to work with, otherwise, when this is changed, it may stop working properly.
Conversation volume
F
IGURE
41.
C
ONFIGURATION OF THE
5.6.2.1 Adaptive echo cancellation
The adaptive echo canceller is configured in the Voice over IP settings (“
following values:
Echo canceller algorithm in a regular communication
Higher output level to cut the microphone input off
Echo canceller filter factor
Echo canceller attenuation for the attenuate scheme
F
IGURE
42.
C
ONFIGURATION OF THE
This is the standard cancellation mode and it consists o
through the microphone, the
algorithm to work you have to continuously calculate the delay that needs to be added to the
output audio so that the right amo
added to the signal before it is removed.
be capable of identifying what was emitted within the return signal, which is rarely possible in
industrial or noisy environments such as car parks, airports, factories etc.
You can test if it works and, if not, you can change the algorithm by added “extra” attenuation
(“
Echo canceller attenuation for the attenuate scheme
or 16). If you do not achieve the desired effect you should try with another cancellation model.
Configuration Guide
Acoustic echo canceller
One of the main disadvantages of “hands free” communications systems is that there is an
With traditional communications systems, this echo has always
occurred on the transition from 2 to 4 wires, but it did not cause any problems for the speaker as
there was no delay. To the contrary, it told the speaker that the line was working properly.
With the introduction of voice communications over switched networks, and subsequently over
IP networks, this delay has increased considerably, even going so far as to hinder proper
n between both points. It therefore became necessary to cancel the echo, so that
the speaker does not hear him/herself speak. This obviously removed one of the major
advantages of traditional communications, the confirmation that the speaker’s voice
It is worth noting that the acoustic echo cancellers that are normally used are
for a “clean” type of environment, i.e. when the speaker talks, the return audio
his/her voice, with minimal distortion, plus the voices speaking on the other end.
the speaker’s voice becomes too distorted (either due to the location of the microphone and
speaker or the volume being too high), the adaptive cancellation algorithm stops working
properly and introduces noises, especially at the beginning and end of sentences.
Given that IPefonos are designed to work in very diverse environments, they incorporate a
variety of echo cancellation mechanisms, so they can be optimised according to the possibilities
The different alternatives that are available are listed below.
Naturally, before configuring the echo canceller, it is essential to set the conversation volume
o work with, otherwise, when this is changed, it may stop working properly.
medium↓
Set the conversation volume control
ONFIGURATION OF THE ACOUSTIC ECHO CANCELLER
(V
O
IP
OPTION
cancellation
The adaptive echo canceller is configured in the Voice over IP settings (“
VoIP
Echo canceller algorithm in a regular communication
suppression
Higher output level to cut the microphone input off
(not used)
(not used)
Echo canceller attenuation for the attenuate scheme
4
ONFIGURATION OF THE ADAPTIVE ECHO CANCELLER
(V
O
IP
OPTION
This is the standard cancellation mode and it consists of removing the return audio that comes
the audio emitted by the speaker, but with a time delay
algorithm to work you have to continuously calculate the delay that needs to be added to the
output audio so that the right amount can be removed, as well as the attenuation that will be
added to the signal before it is removed. In order to calculate these values, the system needs to
be capable of identifying what was emitted within the return signal, which is rarely possible in
industrial or noisy environments such as car parks, airports, factories etc.
You can test if it works and, if not, you can change the algorithm by added “extra” attenuation
Echo canceller attenuation for the attenuate scheme
” settings, with values such a
or 16). If you do not achieve the desired effect you should try with another cancellation model.
5 – Configuration
Configuration Guide. IPefono. V2.8
that there is an echo
With traditional communications systems, this echo has always
occurred on the transition from 2 to 4 wires, but it did not cause any problems for the speaker as
rary, it told the speaker that the line was working properly.
With the introduction of voice communications over switched networks, and subsequently over
IP networks, this delay has increased considerably, even going so far as to hinder proper
It therefore became necessary to cancel the echo, so that
one of the major
that the speaker’s voice is being
used are usually prepared
return audio comes from
his/her voice, with minimal distortion, plus the voices speaking on the other end. However, when
the speaker’s voice becomes too distorted (either due to the location of the microphone and
cellation algorithm stops working
properly and introduces noises, especially at the beginning and end of sentences.
Given that IPefonos are designed to work in very diverse environments, they incorporate a
an be optimised according to the possibilities
The different alternatives that are available are listed below.
Naturally, before configuring the echo canceller, it is essential to set the conversation volume
o work with, otherwise, when this is changed, it may stop working properly.
Set the conversation volume control
OPTION
)
VoIP
” option
)
with the
)
f removing the return audio that comes
, but with a time delay. For this
algorithm to work you have to continuously calculate the delay that needs to be added to the
unt can be removed, as well as the attenuation that will be
In order to calculate these values, the system needs to
be capable of identifying what was emitted within the return signal, which is rarely possible in
You can test if it works and, if not, you can change the algorithm by added “extra” attenuation
” settings, with values such as 2, 4, 8
or 16). If you do not achieve the desired effect you should try with another cancellation model.