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參數(shù)資料
| 型號： | ZL50212 |
| 廠商： | Zarlink Semiconductor Inc. |
| 英文描述： | 288 Channel Voice Echo Canceller |
| 中文描述： | 288頻道語音回聲消除器 |
| 文件頁數(shù)： | 11/43頁 |
| 文件大?。?/td> | 2166K |
| 代理商： | ZL50212 |
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Data Sheet
ZL50212
11
Zarlink Semiconductor Inc.
2.2
Non-Linear Processor (NLP)
After echo cancellation, there is always a small amount of residual echo which may still be audible. The EVP uses
Zarlink’s patented Advanced NLP
to remove residual echo signals which have a level lower than the Adaptive
Suppression Threshold (TSUP in G.168). This threshold depends upon the level of the Rin (Lrin) reference signal as
well as the programmed value of the Non-Linear Processor Threshold register (NLPTHR). TSUP can be calculated
by the following equation:
TSUP = Lrin + 20log
10
(NLPTHR)
where NLPTHR is the Non-Linear Processor Threshold register value and Lrin is the relative power level expressed
in dBm0. The NLPTHR register is 16 bits wide. The register value in hexadecimal can be calculated with the following
equation:
NLPTHR
(hex)
= hex(NLPTHR
(dec)
* 32768)
where 0 < NLPTHR
(dec)
< 1
When the level of residual error signal falls below TSUP, the NLP is activated further attenuating the residual signal
by an additional 30 dB. To prevent a perceived decrease in background noise due to the activation of the NLP, a
spectrally-shaped comfort noise, equivalent in power level to the background noise, is injected. This keeps the
perceived noise level constant. Consequently, the user does not hear the activation and de-activation of the NLP.
The NLP processor can be disabled by setting the NLPDis bit to “1” in Control Register 2.
The comfort noise injector can be disabled by setting the INJDis bit to “1” in Control Register 1. It should be noted
that the NLPTHR is valid and the comfort noise injection is active only when the NLP is enabled.
The patented Advanced NLP provides a number of new and improved features over the original NLP found in
previous generation devices. The differences between the Advanced NLP and the original NLP are summarized in
Table 1.
The NLPSel bit in Control Register 3 selects which NLP is used. A “1” will select the Advanced NLP, “0” selects the
original NLP.
The Advanced NLP uses a new noise ramping scheme to quickly and more accurately estimate the background
noise level. The noise ramping method of the original NLP can also be used. The InjCtrl bit in Control Register 3
selects the ramping scheme.
Feature
Register or Bit(s)
Advanced
NLP Default
Value
Original NLP
Default Value
NLP Selection
NLPSel (Control Register 3)
1
0 (feature
not supported)
Reject uncanceled echo as noise
NLRun1 (Control Register 3)
1
0 (feature
not supported)
Reject double-talk as noise
NLRun2 (Control Register 3)
1
0 (feature
not supported)
Noise level estimator ramping scheme
InjCtrl (Control Register 3)
1
0 (feature
not supported)
Noise level ramping rate
NLInc (Noise Control)
5(hex)
C(hex)
Noise level scaling
Noise Scaling
16(hex)
74(hex)
Table 1 - Comparison of NLP Types
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ZL50232GDC | 32 Channel Voice Echo Canceller |
| ZL50232QCC | Aluminum Electrolytic Capacitor; Capacitor Type:General Purpose; Voltage Rating:35VDC; Capacitor Dielectric Material:Aluminum Electrolytic; Operating Temperature Range:-40 C to +85 C; Capacitance:47uF RoHS Compliant: Yes |
| ZL50232QCC1 | 32 Channel Voice Echo Canceller |
| ZL50232 | 32 Channel Voice Echo Canceller |
| ZL50233GD | 4 Channel Voice Echo Cancellor |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ZL50212/GBC | 制造商:Microsemi Corporation 功能描述:ECHO CANCELLER CHIP 288CH G.164/G.165/G.168/G.711 W/ TONE DE - Trays |
| ZL50212GB | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Telecomm/Datacomm |
| ZL50232 | 制造商:ZARLINK 制造商全稱:Zarlink Semiconductor Inc 功能描述:32 Channel Voice Echo Canceller |
| ZL50232/GDC | 制造商:Microsemi Corporation 功能描述:ECHO CANCELLER CHIP 32CH G.164/G.165/G.168/G.711 W/ TONE DET - Trays |
| ZL50232/QCC | 制造商:Microsemi Corporation 功能描述:ECHO CANCELLER CHIP 32CH G.164/G.165/G.168/G.711 W/ TONE DET - Trays |
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