zl50232 Zarlink Semiconductor, zl50232 Datasheet - Page 33

• Manufacturer Part Number: zl50232
• Description: 32 Channel Voice Echo Canceller
• Manufacturer: Zarlink Semiconductor

The Table 5 below is the same as Table 1 shown on page 12)
NLP Selection
Reject uncancelled echo as noise
Reject double-talk as noise
Noise level estimator ramping
scheme
Noise level ramping rate
Noise level scaling
NLRun2
NLRun2
NLRun1
Reserve
PathDet
NLPSel
RingClr
PathClr
InjCtrl
Bit 7
Power-up
FB
hex
When high, the comfort noise level estimator actively rejects double-talk as being background
Reserved bit. Must always be set to one for normal operation.
noise. When low, the noise level estimator makes no such distinction.
Selects which noise ramping scheme is used. See Table below.
When high, the comfort noise level estimator actively rejects uncancelled echo as being
background noise. When low, the noise level estimator makes no such distinction.
When high, the instability detector is activated. When low, the instability detector is disabled.
When high, the current echo channel estimate will be cleared and the echo canceller will enter
fast convergence mode upon detection of a path change. When low, the echo canceller will keep
the current path estimate but revert to fast convergence mode upon detection of a path change.
Note: this bit is ignored if PathDet is low.
When high, the path change detector is activated. When low, the path change detector is
disabled.
When high, the Advanced NLP is selected. When low, the original NLP is selected.
Feature
InjCtrl
Bit 6
NLRun1
Bit 5
Table 5 - Comparison of the NLP Types
Functional Description of Register Bits
NLPSel (Control Register 3)
NLRun1 (Control Register 3)
NLRun2 (Control Register 3)
InjCtrl (Control Register 3)
NLInc (Noise Control)
Noise Scaling
ECA: Control Register 3
ECB: Control Register 3
Zarlink Semiconductor Inc.
RingClr
Register or Bit(s)
Bit 4
ZL50232
33
Reserve
Bit 3
PathClr
NLP Default
Bit 2
Advanced
Value
16
5
hex
1
1
1
1
hex
08
28
PathDet
Bit 1
hex
hex
R/W Address:
R/W Address:
+ Base Address
+ Base Address
not supported)
not supported)
not supported)
not supported)
Default Value
Original NLP
0 (feature
0 (feature
0 (feature
0 (feature
74
C
Data Sheet
hex
hex
NLPSel
Bit 0