Aec Tutorial - Extron electronics DTP CrossPoint 4K Series User Manual

Export a building blocks file from within the Organize Building Blocks dialog box,
as follows:
1.
Click the
opens.
2. Browse to the location where the file is to be saved.
3. In the
4. Click
Save

AEC Tutorial

The DTP CrossPoint 4K Series provide an acoustic echo cancellation processor for each of
the four mic/line inputs. A single reference can be selected for each AEC from a list of the
other three mic/line inputs or the virtual returns.
About AEC
Echo occurs when audio from a talker in the far end is received and amplified into the room
of the near end listener. That sound is then being picked up by microphones in the near end
acoustic space and sent back to the far end. The amount of signal sent back to the far end
talker can be substantial, and with the added transmission delay, the result is an echo effect
that seriously compromises communication in a teleconference or video conference.
The acoustic echo cancellation processor removes the potential echo signal at the near
end mic channel by comparing it to the received signal from the far end, designated as the
"reference," and then creating an adaptive filter to cancel the potential echo before it is sent
back to the far end.
AEC Setup
Successful operation of the AEC processing block is a function of selecting the AEC
reference. It is also important to optimize the audio levels of the DTP CrossPoint 4K for AEC
to be effective (see
of the selection of the two references.
Proper gain structure involves the relationship between the signal at the selected reference
and the signal at the mic input, within the context of proper levels for the reference and mic
inputs independently. The mic input gain setting is naturally optimized for the voice level of
the talker in that room. Therefore the amount of signal from the far end that is picked up
by the mic is dependent on how much that far end signal is being amplified in the near end
room and the distance from the mic to the speakers.
The reference signal is the signal received from the far end, which is sent to a sound
reinforcement system in the near end room. The output of the video codec may be connected
to the matrix line inputs, or to the mic inputs. The codec input can also come from the expansion
port inputs. If the codec input comes from either the expansion port or line inputs, the signal
must be routed to the virtual return path to be selected as an AEC reference.
In the AEC dialog box, a reference can be chosen from either of the following signal chains:
Mic/line inputs
•
• Virtual return channels
Extron recommends using a mic/line input channel as the reference. A virtual return channel
can be used as a reference; however, doing so adds a little more delay to the signal being
referenced.
Using a virtual return channel as reference allows for the combining of input channels to a
single reference, for example, in a conferencing setup where both a telephone and a video
codec are used. In this case, both the telephone and video codec input channels can be
routed to a virtual return, with that virtual return then chosen as the reference.
Export Building Blocks File
field, leave the current file name or enter a new file name.
File Name
.
Optimizing the Audio
DTP CrossPoint 4K Series Matrix Switchers • Matrix Software
icon ( ). The
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on page 148). This section provides an overview
dialog box
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