AT2004
4 Channels ADPCM Processor with Echo Cancellation and Conferencing
Atelic Systems, Inc.
AT2004 Application Note Preliminary
4 Channels ADPCM Processor with Echo Cancellation and Conferencing
Version 1.0 January 29, 2001
Description
The AT2004 is a four full-duplex channels, ADPCM processor with conferencing and echo cancellation capabilities. It
follows the G.726 ITU Standard for ADPCM compression for 40k, 32k, 24k and 16k bitrates with selectable m-law and A-
law input/output. It conforms to ITU G.165/G.168 Digital Adaptive Echo Canceller specification for line echo delay up to
20ms. Using the command serial interface, each individual half-channel can be independently configured for ADPCM,
conferencing and echo canceling features.
Features
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4 full channels of ITU G.726 ADPCM
4 full channels of ITU G.165/G.168 compliant echo cancellation with up to 20ms echo delay
Fast and robust convergence for adaptive echo canceller, even in the presence of background noise
Nonlinear processing with adaptive suppression threshold and comfort noise generation for echo canceller
Per channel selectable m-Law and A-law input/output
On-chip time slot assignment
Available internal clock generator and frame sync. generator
Simple 3-wire serial command port for chip configuration
Conferencing capabilities for up to 3 additional sound sources
Applications
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DECT
VoIP / VoDSL
Wireless telephone systems
Wireless PBX systems
Default Settings
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4 channels of m-law PCM input on Xin in time slot 0, 1, 2, 3
4 channels of the corresponding ADPCM output at 32kbps on Xout in time slot 0, 1, 2, 3
4 channels of ADPCM input at 32kbps on Yin in time slot 0, 1, 2, 3
4 channels of corresponding PCM m-law output on Yout in time slot 0, 1, 2, 3
Echo cancellation enabled for four channels
Conferencing disabled
Note: To change the default settings, commands could be sent through the 3-wire interface.
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©2001 Atelic System, Inc