Cirrus-logic AN168 Manuel d'utilisateur télécharger pdf (Page 28)

AN168

28 AN168REV2

1.7.4 Acoustic coupling

The maximum acoustic coupling (across

frequency) between the speaker and the

microphone should be limited to -9 dB. This can be

tested and verified by using techniques described

earlier.

1.7.5 Training sequence

The Acoustic Echo Canceler trains only when the

far-end is talking while the near-end is silent. When

the system is in half-duplex mode, the AEC trains

whenever the receive path is active. When the

system is in full-duplex mode, the AEC does not

train during double-talk. It is only when the

near-end is silent while the far-end is talking that

the acoustic adaptive filter trains.

The Network Echo Canceler trains only when the

near-end is talking and the far-end is silent. When

the system is in half-duplex mode, the NEC trains

when the transmit path is active.

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Cirrus-logic AN168 Manuel d'utilisateur Page 28