User`s manual

VLSI

Solution

VS1000+1003 VoIP Speaker Phone VSMPG

6. ECHO CANCELLATION

6 Echo Cancellation

6.1 What Is Echo Cancellation

Echo cancellation is a method to reduce energy returning from a speaker to a microphone.

The reason for using echo cancellation is presented below.

6.1.1 Headsets Are Usually Not a Problem

PC PC

Speaker

Near−End

Speaker

Far−End

FESFES

FES

NES

NESFES

NES

Internet

NES

Figure 6.1: VoIP Conversation using Two Headsets

VoIP protocols like Skype are typically designed to work with headsets that have good

separation between the earphones and the microphone.

Figure 6.1 shows two telephone application users who are both using headsets. Because

there is no signiﬁcant leakage between from the earphones to the microphones, there is

no disturbing echo.

Rev. 2.12

2008-09-18

Page 20(30)