Cirrus Logic AN168 - Manual (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.