CDB6420 Просмотр технического описания (PDF) - Cirrus Logic

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CDB6420

Full-Duplex Speakerphone Chip

Cirrus Logic 

CS6420

Register 0

b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0

Mic TSD

GB

1

0

10

ACC

00

RVol

00100

TGain

00

0

0

0

0

0

0

Bits Name

15 Mic

14 TSD

Function

Microphone Preamplifier Enable

Tx Suppression Disable

13-12 GB

Graded Beta

11-10 ACC

AEC Coefficient Control

9-5 RVol

Rx Volume Control

4-3 TGain

Tx Analog Gain

Word

0

1*

0*

1

00

01

10*

11

00*

01

10

11

00000

00001

---

00100*

---

01010

01011

---

11101

11110

11111

00*

01

10

11

Operation

disable preamp

enable preamp

enable Tx suppression

disable Tx suppression

0.00 dB/ms

0.75 dB/ms

0.38 dB/ms

0.19 dB/ms

Normal

Clear

Freeze

reserved

+30 dB

+27 dB

+18 dB

+0 dB

-3 dB

-57 dB

-60 dB

mute

0 dB

6 dB

9.5 dB

12 dB

* Denotes reset value

Table 3. Register 0 Bit Definitions

Mic - Microphone Preamplifier Enable

The microphone preamplifier described in the

Acoustic Interface section is enabled by default, but

may be disabled by setting Mic to 0. Refer to the

Acoustic Interface section for more details on us-

ing/disabling the Microphone Preamplifier.

TSD - Transmit Suppression Disable

The Transmit Supplementary Echo Suppression

function is a non-linear echo control mechanism.

The Transmit Suppression will introduce TSAtt

(see Register 3) dB of attenuation into the transmit

path only when there is speech detected in the re-

ceive path and no near-end speech. When only

near-end speech is present, or if there is no speech

in either direction, the suppression attenuation is

removed. By default, the transmit suppression

function is enabled.

GB - Graded Beta

The room-size adjustment scheme called “graded

beta,” provided for the acoustic echo canceller in the

12

DS205PP2

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