ECHO Canceller Chip 1-CH G.711 With Tone Detection 48-Pin TQFP Tray

The ZL38002 device is comprised of an acoustic echo canceller and the necessary control functions for operation. The ZL38002 guarantees clear signal transmission in both transmit and receive audio path directions to ensure reliable voice communication, even when low level signals are provided. The ZL38002 does not use variable attenuators during double-talk or single-talk periods of speech, as do many other acoustic echo cancellers for speakerphones. Instead, the ZL38002 provides high performance full-duplex operation similar to network echo cancellers. This results in users experiencing clear speech and uninterrupted background signals during the conversation and prevents subjective sound quality problems associated with “noise gating” or “noise contrasting”. The ZL38002 uses an advanced adaptive filter algorithm that is double-talk stable, which means that convergence takes place even while both parties are talking. This algorithm allows continual tracking of changes in the echo path, regardless of double-talk, as long as a reference signal is available for the echo canceller.The echo tail cancellation capability of the acoustic echo canceller has been sized appropriately (112 ms) to cancel echo in an average sized office with a reverberation time of less than 112 ms

• 112 ms acoustic echo canceller
• Up to 12 dB of noise reduction
• Works with low cost voice codec. ITU-T G.711 orsigned mag µ/A-Law, or linear 2’s compliment
• Each port may operate independently in companded format or linear format
• Advanced NLP design - full duplex speech with no switched loss on audio paths
• Fast re-convergence time: tracks changing echo environment quickly
• Adaptation algorithm converges even during Double-Talk
• Designed for exceptional performance in high background noise environments
• Provides protection against narrow-band signal divergence
• Howling prevention stops uncontrolled oscillation in high loop gain conditions
• Programmable offset nulling of all PCM channels
• Serial micro-controller interface
• Idle channel noise suppression
• ST-BUS, GCI, or variable-rate SSI PCM interfaces
• User gain control provided for speaker path (-24 dB to +21 dB in 3 dB steps)
• Adjustable gain pads from -24 dB to +21 dB at Xin, Sin and Sout to compensate for differentsystem requirements
• AGC on speaker path
• Handles up to -6 dB acoustic echo return loss(with the appropriate gain pad settings)
• Transparent data transfer and mute options
• 20 MHz master clock operation
• Low power mode during PCM Bypass
• Boot loadable for future factory software upgrades
• 2.7 V to 3.6 V supply voltage; 5 V-tolerant inputs