Cisco Cisco TelePresence MX700 Guida Utente

D15029.01 Troubleshooting Guide TC6.0, April 2013. 

Copyright © 2013 Cisco Systems, Inc. All rights reserved. 

15

Echo issues (echo cancellation)

The cause of echo problems can be:

• 

Using internal speakers on a modern consumer TV. See below for explanation and techniques 

to fix this.

• 

Echo issues may occur immediately after restarting the system. 

• 

Movement of the microphones or speakers during a call.

• 

Double-talk – both parties in the call speaking simultaneously.

• 

Very high noise levels

• 

Having the microphone too close to the speakers. Try moving the microphone further away.

• 

Having echo cancellation disabled.

You can see more information regarding room setup recommendations in the 

: 

NOTE

 The most likely cause for an echo heard locally is a problem with the far-end system.

General checks

Check that the input for each microphone you have connected to the system has echo control turned 

on. This is the default setting. if it is turned off the far-end will hear themselves. Echo control should 

only be turned off when using an external echo cancellation.

Using internal speakers on a modern TV

if you are using the internal speakers on a modern TV the various picture enhancing modes on the 

TV delay the audio whilst the image is being processed. This can result in the audio being outside the 

acceptable window for echo cancellation thus causing the far end to hear an echo.

There are various workarounds to try if you are experiencing this problem:

• 

Try and experiment on the TV with various picture modes looking for the one that processes 

the image the least. This can be called for example 

Game mode on some TVs.

• 

rather than trying to use the internal speakers on the TV, use an external amplifier and speak-

ers or powered speakers and see if this resolves the problem.

• 

You can experiment with the experimental setting 

ECReferenceDelay and try changing this 

from 0 to a higher value. The setting is located under 

 and look under ExRefernceDelay.

Pop noise after unexpected restart

if the system restarts unexpectedly, and occasionally even during a controlled restart, you might hear a 

popping noise from the systems audio speakers. This is a normal operation and is not considered a fault.

Custom Audio TC Console (C40, C60, C90)

You can use the TC Console to configure advanced audio settings on the C40, C60 and C90 codecs. 

For more detail on TC Console please see the developer forum at 

. Documentation can be found within the application.

You should be aware that once these settings are synced to the codec a script is executed at startup 

and these settings are persistent.

You can also use this application to check the microphones. For more information on this see 

Troubleshooting Guide TC6.0