MT93L04 Zarlink Semiconductor, MT93L04 Datasheet - Page 40

• Manufacturer Part Number: MT93L04
• Description: 128-channel Voice Echo Canceller
• Manufacturer: Zarlink Semiconductor

Echo Canceller A, Noise Scaling (NS)
Echo Canceller B, Noise Scaling (NS)
Echo Canceller A, Injection Rate (IR)
Echo Canceller B, Injection Rate (IR)
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
use a value of 8Fh (1 dB = 112% of original level, 1.12
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.
6-4
3-0
Bit
0
7
Echo Canceller A, Control Register A4
Echo Canceller B, Control Register B4
NS7
IR7
7
7
SD
6
2
SupDec
Name
NS6
IR6
res
SD
6
6
5
1
SD
NS5
IR5
4
5
5
0
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.
Reserved bits. Must always be set to zero for normal operation.
res
3
NS4
IR4
4
4
res
2
NS3
IR3
3
3
res
1
Zarlink Semiconductor Inc.
NS2
IR2
2
2
res
MT93L04
0
NS1
IR1
40
1
1
(dec)
(dec)
Read/Write Address: 09
Read/Write Address: 29
Reset Value:
Description
• 80h = 8Fh).
NS0
IR0
• 80h = 72h). Similarly, to scale up by 1 dB,
0
0
Read/Write Address:
Read/Write Address:
Read/Write Address:
Read/Write Address:
50
H
H
H
0Bh
2Bh
+ Base Address
+ Base Address
.
0Ah
2Ah
+ Base Address
+ Base Address
+ Base Address
+ Base Address
Power Reset Value
Power Reset Value
0Ch
74h
Data Sheet