CDB6422 Просмотр технического описания (PDF) - Cirrus Logic

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CDB6422

Enhanced Full-Duplex Speakerphone IC

Cirrus Logic 

CS6422

6. GLOSSARY

Echo

A signal that returns to its source after some delay.

Network Echo

Echo resulting from signal reflection due to an impedance mismatch in a 2-to-4 wire converter (hybrid).

Acoustic Echo

Echo created by signal propagation in a room from a speaker to a microphone.

Reverberation

Local information that bounces around the room before it reaches the microphone. An example of

reverberation is when your back is to the speakerphone, and your voice bounces off the wall before it

reaches the microphone.

Near-End

The location with the acoustic interface (speaker and microphone).

Far-End

The location connected to the network interface.

Transmit Path

The signal path from Near-End input to Far-End output.

Receive Path

The signal path from Far-End input to Near-End output.

Full-Duplex

The state when both Transmit and Receive paths are simultaneously active.

Half-Duplex

The state when either Transmit or Receive path is active.

Supplementary Echo Suppression

Dynamic attenuation placed in the opposite path of the active path to mask residual echo. For example,

if the receive path is active, the transmit path is attenuated. When both paths are simultaneously active,

the suppression attenuation is removed. See Section 4.1.4, “Suppression” for more details.

Howling

In full-duplex operation, both the microphone and speaker are active at the same time, which, in

conjunction with the reflection off the hybrid, creates a closed loop. The signal coupling between the

speaker and the microphone can cause feedback oscillation or howling. This happens when the

coupling between the speaker and microphone is strong enough to increase the system's closed loop

gain above unity.

Acoustic Coupling

The strength of the output signal from the speaker that is received at the microphone input.

DS295F1

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