peb20954 Infineon Technologies Corporation, peb20954 Datasheet - Page 12

• Manufacturer Part Number: peb20954
• Description: Smart Integrated Digital Echo Canceller Sidec
• Manufacturer: Infineon Technologies Corporation

Preliminary Data Sheet
Figure 5
Due to voice compression and error correction the one way transmission time for
wireless voice signals is typically 90 ms. With 180 ms roundtrip time the 50 ms roundtrip
time for echo free transmission is exceeded by at least 130 ms. Hence, the speaker on
the mobile phone will hear any kind of echo generated in the hybrid next to the POTS or
the acoustical echo of the POTS. The SIDEC suppresses those two kinds of echoes if it
is incorporated in the MSC. Depending on the individual call the end echo path can differ
dramatically. In Europe the end echo path could even go to different countries causing
strong dispersion of the echo. Only a high quality echo canceller with long end path delay
options guarantees compensation of the strongly varying echoes.
POTS
POTS
POTS
POTS
Echo
SIDEC in a Wireless System
E1/T1
TRAU:
MSC:
SIDEC
Transcoder Rate Adaptor Unit
Mobile Switching Center
MSC
12
TRAU
TRAU
BTS
BSC:
BTS:
Base Station Controller
Base Transceiver Station
round trip time: 180 ms
BSC
BTS
BTS
Introduction
PEB 20954
PEF 20954
BTS
04.99