Acoustic Echo Cancellation

Description/Objective

In this section, we will be discussing Acoustic Echo Cancellation, or "AEC". Its purpose is to remove audio feedback in a control room solution, with 2 mics and 2 speakers.

Physical Wiring/Line Diagram

We will use the CRAS example configuration. The physical wiring is as follows:

Tesira Software

Connections

We will use the same software example config too, which looks like this:

AEC Block

1. Phantom Power: We will need phantom power on for our mics, and proper levels on the preamps.
2. AEC: Enable the AEC feature with this button on the AEC Block.

How the AEC Block Works

1. • Let's say John is in the Control Room, using the push to talk mic. We are sending his audio 2 places: the camera and the OWISP.
   • Steve is in the simulation room, responding in kind to John's instructions. Steve's audio is going 2 places also: the camera and the PSP speaker in the control room.
   • John's OWISP audio will be captured by the room mic, and therefore sent back to the PSP speaker.
   • Steve's PSP audio will be captured by the push to talk mic, and therefore sent back to the sim room over the OWISP.
   • The Tesira AEC Block will remove the unwanted audio coming into the mic inputs, as long as we tell it what to cancel.
   • We have to send the audio we need cancelled to the AEC Reference block.

How to use the Mixer

There are 2 ways we can achieve our goal. They are functionally the same, but one may be conceptually easier to understand, and therefor configure correctly. We will look at them both here.