CDB6420 Cirrus Logic Inc, CDB6420 Datasheet - Page 36

• Manufacturer Part Number: CDB6420
• Description: Development Kit
• Manufacturer: Cirrus Logic Inc

Specifications of CDB6420

• Silicon Manufacturer: Cirrus Logic
• Application Sub Type: Speakerphone
• Kit Application Type: Audio / Video / TV
• Silicon Core Number: CS6420
• Kit Contents: Board
• Kit Features: Analog And Digital Patch Area
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Coverage Time
Convergence Time
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The CS6420 echo canceller has 508 taps and it can sample an analog signal at an 8 kHz rate.
512 x 1/8kHz = 63.5 ms. Sound travels through air at a rate of around 1 ft/ms. Thus the echo
canceller can be used in a room with walls 32 feet away, discounting multiple reflections. But
remember that at this distance, most of the echo has been attenuated due to the physical
separation. The majority of the acoustic coupling comes from the first arrival, or directly from
the speaker to the microphone. The first signal is by far the strongest.
A high quality echo canceller is continuously modifying its internal model of the echo path
characteristics (See Adaptive Filter). When the model is complete, the echo canceller will be
able to cancel echo to the extent of its rated capabilities. Convergence time is the duration it
takes the echo canceller to train itself, from cleared coefficients, and switch to full-duplex
operation, in the presence of speech.
CS6420
DS205PP2