CS6420-CS datasheet(36/52 Pages) CIRRUS

36 / 52 page

CS6420

DS205PP2

Coverage Time

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.

Convergence Time

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-CS Datasheet(PDF) 36 Page - Cirrus Logic