peb20954 Infineon Technologies Corporation, peb20954 Datasheet - Page 126

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

PEB 20954
PEF 20954
Glossary
9
Glossary
acoustic echo
Acoustic echoes consist of reflected signals caused by acoustic environments, e.g.
hands-free phones which are connected with a 2-wire circuit to a hybrid. An echo path is
introduced by the acoustic path from earphone to microphone.
combined loss (A
)
COM
The sum of echo return loss, echo return loss enhancement and non-linear processing
loss (if present). This loss relates L
to L
by:
Rin
RET
L
= L
- A
, where:
RET
Rin
COM
A
= A
+ A
+ A
COM
ECHO
CANC
NLP
comfort noise
Insertion of pseudo-random noise during the silent interval when the NLP operates or
allowance of some of the background or idle channel noise to pass through the NLP in
order to prevent the annoyance of intervals of speech with background noise followed by
intervals of silence.
composite echo
Composite echoes consist of the electric echoes and acoustic echoes caused by
reflected signals at hybrids and acoustic environments, e.g. hands-free telephones.
convergence
The process of developing a model of the echo path which will be used in the echo
estimator to produce the estimate of the circuit echo.
convergence time
For a defined echo path, the interval between the instant a defined test signal is applied
to the receive-in port of an echo canceller with the estimated echo path impulse
response initially set to zero, and the instant the returned echo level at the send-out port
reaches a defined level.
echo canceller
A voice-operated device placed in the 4-wire portion of a circuit and used for reducing
near-end echo present on the send path by subtracting an estimation of that echo from
the near-end echo (see Figure 42)
Preliminary Data Sheet
126
04.99