MT93L00A Datasheet, PDF (24/39 Pages) Zarlink Semiconductor Inc – Multi-Channel Voice Echo Canceller

MT93L00A
Data Sheet
Echo Canceller A, Control Register A4
Echo Canceller B, Control Register B4
765432 10
0
SD₂ SD₁ SD₀
res
res
res
res
Read/Write Address: 09_H + Base Address
Read/Write Address: 29_H + Base Address
Reset Value:
50_H.
Bit
Name
Description
7
0
Must be set to zero.
6-4
SupDec These three bits control how long the echo canceller remains in a fast convergence
state following a path change, Reset or Bypass operation. A value of zero will keep
the echo canceller in fast convergence indefinitely.
3-0
res
Reserved bits. Must always be set to zero for normal operation.
Echo Canceller A, Noise Scaling (NS)
Echo Canceller B, Noise Scaling (NS)
Read/Write Address: 0Ah + Base Address
Read/Write Address: 2Ah + Base Address
7
6
5
4
3
2
1
0
NS₇
NS₆
NS₅
NS₄
NS₃
NS₂
NS₁
NS₀
Power Reset Value
74h
If the comfort noise level estimator is unable to correctly match the background noise level, this register can be used to scale the
comfort noise up or down. A neutral value of 80h will prevent any scaling. Values less than 80h will scale the comfort noise level
down. Values greater than 80h will scale the comfort noise level up. Scaling is done linearly, so to scale the comfort noise down by
1 dB, a value of 72h would be used (-1 dB = 89% of original level, 0.89_(dec) • 80h = 72h). Similarly, to scale up by 1 dB, use a value of
8Fh (1 dB = 112% of original level, 1.12_(dec) • 80h = 8Fh).
Echo Canceller A, Injection Rate (IR)
Echo Canceller B, Injection Rate (IR)
Read/Write Address: 0Bh + Base Address
Read/Write Address: 2Bh + Base Address
7
6
5
4
3
2
1
0
IR₇
IR₆
IR₅
IR₄
IR₃
IR₂
IR₁
IR₀
Power Reset Value
0Ch
The NLP ramps-in comfort noise during the initial background noise estimation stage. This register provides control over the
ramp-in speed. Higher values will increase the ramp-in speed.
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