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AT2004
4 Channels ADPCM Processor with Echo Cancellation and Conferencing
Page 5 of 25
©2001 Atelic System, Inc
Echo Canceller Block Diagram:
DC
Remover
NLP
M
U
X
Adaptive
Filter
DC
Remover
Double Talk
Detector
Narrow Band
Signal Detector
Disabling Tone
Detector
No. 5, 6, 7
Signalling Tone
Detector
Dc_rmv
Comfort
Noise NLP_flag
EC
Bypass
-
Stepsize
Freeze
Dc_rmv
Tone_flag
• A dotted line with arrow mark indicate the control bit in the per channel control command, such
as LawP, EC reset, LawA, ADPCM bypass, ADPCM reset, Channel bypass, Dc_rmv, Comfort
noise, NLP_flag, EC bypass, Stepsize, Freeze and Tone_flag. Please refer to page 10, 11 and
12 for detail information.
• Only one full channel is shown. AT2004 has additional capability to process up to 4 full
channels simultaneously.
Note:
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