TrueSpeech® Co-Processor
PRELIMINARY/CONFIDENTIAL
Version: 1.18
9.15.6
AEC Train-and-Lock
The CT8022 AEC includes features that allow it to cancel fixed non-acoustic echoes. For example, the AEC can be
used to cancel electrical echoes created by a 2-to-4-wire telephone hybrid.
When the AEC is used to cancel acoustic echoes, it must cope with real-time changes in the echo path of the acoustic
signal. These changes may be caused by movement of the user in front of the speaker and microphone, or by actual
physical movement of the speaker or microphone. As a result, the AEC must continuously attempt to adapt and
search for the optimum echo cancellation setting. The constant search process inevitably means that the AEC may
not always be operating at its optimum.
If the AEC is required to cancel a fixed path electrical echo, it is possible to train the AEC against the fixed path and
then lock the AEC training control.
The AEC can be instructed to perform an automatic train-and-lock sequence using the following command:
Command Status Response
C1 E012
C2 4004
E012
4004
If the AEC is already locked when this command is set, the AEC is unlocked, allowing re-training.
To de-activate the train-and-lock feature, use the following command sequence:
Command Status Response
C1 E012
C2 0004
E012
0004
To force the AEC into a locked state, use the following sequence:
Command Status Response
C1 E012
C2 C004
E012
C004
Refer to Section 9.15.6.1 for a detailed description of the Train & Lock command.
112
DSP GROUP, INC., 3120 SCOTT BOULEVARD CT8022A11AQC FW Revision 0118
SANTA CLARA, CA 95054 PH: 408 986 – 4300 FAX: 408 986 – 4490
All specifications are subject to change without prior notice.
ETC [ ETC ]
