Cisco Unified MeetingPlace

Document ID: 48248

Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
Echo Cancellation
      Troubleshoot
      Set the Delay of the Echo Canceller
      Delay Values
Related Information

Introduction

This document explains how the Cisco MeetingPlace server handles echo.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

The information in this document is based on Cisco MeetingPlace server software: all versions (PCI).

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Conventions

For more information on document conventions, refer to the Cisco Technical Tips Conventions.

Echo Cancellation

Echo cancellation is done on the port level on the Cisco MeetingPlace server. Each port resource card (PRC) on the Cisco MeetingPlace server has a set number of ports, and each port has its own echo canceller. The canceller cancels echo for inbound signals only.

The two types of echo most commonly encountered in the field are line and acoustic echo. Line echo is usually due to signal reflections within the device itself or within the network in which the signal travels. Acoustic echo is due to the surroundings of the device being used. A "live" room (that is, a room that has a lot of smooth surfaces) is usually a good candidate for acoustic echo.

As mentioned before, echo canceling is done on the port level on the Cisco MeetingPlace server. The maximum delay that the echo canceller can handle is 128 ms. If the echo is greater than 128 ms, the echo canceller does not cancel the echo. Of the two types of echo described above, the echo canceller has the most trouble with acoustic echo. This is because echo delays for acoustic echo are usually greater than 128 ms. Line echo is usually completely canceled by the echo canceller because the delay is usually within 128 ms.

Troubleshoot

When an echo is encountered in a meeting, it is recommended that you mute all parties in the meeting and then unmute each port until the cause is found.

Set the Delay of the Echo Canceller

The echo canceller delay is a parameter that is set directly on the Cisco MeetingPlace server. It can be set for an individual port or for a port group. To set this parameter, you must issue the configport command on the Cisco MeetingPlace server. If you are not familiar with this command, contact Cisco Technical Support for assistance. The parameter that must be changed is Echo Control. To avoid problems and anomalies, it is strongly recommended that these changes be performed when there is no activity on the system. After the changes, you must restart the Cisco MeetingPlace server.

Delay Values

16ms = 000
32ms = 004
64ms = 00c
128ms = 01c

Related Information

• Conferencing Software
• Voice Technologies
• Voice, Telephony and Messaging Devices
• Voice Software
• Recommended Reading: Troubleshooting Cisco IP Telephony
• Technical Support - Cisco Systems