MSM7719-01 Datasheet, PDF (34/40 Pages) OKI electronic componets – Echo Canceler with ADPCM Transcoder

¡ Semiconductor
MSM7719-01
(10) CR9 (Setting of acoustic echo canceler operating mode)
CR9
Initial value
B7
ATHR
1
B6
ADCL
0
B5
ACCL
0
B4
B3
B2
B1
B0
ACLP
AHLD
AATT
AGC
AHD
(NLP)*1 (ADP)*1 (ATT)*1 (GC)*1
0
0
0
0
0
*1 Name of a control pin used by the MSM7602
B7 … Through mode control bit for acoustic echo canceler.
In this mode, RinA data and SinA data is output directly to RoutL and SoutL respectively.
The coefficient is not cleared.
1: Through mode 0: Normal mode (echo cancellation)
B6 … Selects whether or not to clear the coefficient 1 of the adaptive FIR filter (AAFF) for the
acoustic echo canceler.
1: Resets the coefficient 0: Normal operation
B5 … Selects whether or not to clear the coefficient 2 of the adaptive FIR filter (AAFF) for the
acoustic echo canceler.
1: Resets the coefficient 0: Normal operation
B4 … Howling detector (HD) ON/OFF control
1: ON 0: OFF
B3 … Turns ON or OFF the Center Clipping function which forcibly sets the Sout output of the
acoustic echo canceler to a minimum positive value when it is –57 dBm0 or less.
1: Center Clipping ON
2: Center Clipping OFF
B2 … Selects whether or not to update the coefficient of the adaptive FIR filter (AAFF) for the
acoustic echo canceler.
1: Coefficient fixed mode
0: Normal mode (updates the coefficient.)
B1 … Turns ON or OFF the ATT function which prevents howling from occurring by means of
attenuators ATTrA and ATTsA provided for the RinA input and the SoutA output of the
acoustic echo canceler.
When a signal is input to RinA only, the attenuator ATTsA of the SoutA output is
activated. When a signal is input to SinA only or to both SinA and RinA, the attenuator ATTrA
of the RinA input is activated. Their ATT values are both about 6 dB.
1: ATT function OFF
0: ATT function ON
B0 … Turns ON or OFF the gain control function which controls the RinA input level and
prevents howling from occurring by the gain controller (GainA) for the RinA input of the
acoustic echo canceler.
The RinL/A input level is adjusted in the attenuation range of 0 to –8.5 dB. This adjusting starts
at the RinL/A input level of –24 dBm0.
1: Gain control ON
0: Gain control OFF
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