CT8022 Datasheet, PDF (110/194 Pages) List of Unclassifed Manufacturers – VOIP/VON G.723.1, G279AB TRUESPEECH CO-PROCESSOR

TrueSpeech® Co-Processor
PRELIMINARY/CONFIDENTIAL
Version: 1.18
Large duration (> 100ms) multi-path echoes can be handled using echo cancellers with very long filter lengths (512-
1024 tap filters) or using multiple sub-band (frequency division) techniques. This approach tends to require
significant computation and processing resources resulting in a relatively high-cost solution.
In cost sensitive applications, acoustic type echoes are more appropriately handled using techniques like NLP and
AS/AB together with some degree of Echo Suppression.
High background noise levels and non-linear echo paths tend to reduce the amount of echo cancellation achieved,
thus requiring increased reliance on the NLP/AS/AB features to compensate.
C1
E011H
Set NLP threshold floor
S1
E011H
C2
0100H
Use higher threshold floor value
S2
0100H
C1
E013H
Set Attenuation Scaling
S1
E013H
C2
0002H
Set attenuation scale factor to x2
S2
0002H
C1
E012H
Train & Lock Command
S1
E012H
C2
0023H
NLP threshold = Speaker Output >> 3 (divided by 8)
NLP Mode = 1, activate NLP/AS based on measured AEC attenuation
S2
0023H
C1
E014H
Set lock threshold (used to activate NLP/AS)
S1
E014H
C2
0003H
Set threshold to 3dB measured attenuation
S2
0003H
Example: Telephone Echo environment (local 2-to-4 wire hybrid provides 6-12 dB or cancellation - large amplitude
echoes).
C1
E011H
Set NLP threshold floor
S1
E011H
C2
0080H
Use lower threshold floor value
S2
0080H
C1
E013H
Set Attenuation Scaling
S1
E013H
C2
0002H
Set attenuation scale factor to x2
S2
0002H
C1
E012H
Train & Lock Command
S1
E012H
C2
0024H
NLP threshold = Speaker Output >> 4 (divided by 16)
NLP Mode = 1, activate NLP/AS based on measured AEC attenuation
S2
0024H
C1
E014H
Set lock threshold (used to activate NLP/AS)
S1
E014H
C2
0006H
Set threshold to 6dB measured attenuation
S2
0006H
110
DSP GROUP, INC., 3120 SCOTT BOULEVARD
CT8022A11AQC FW Revision 0118
SANTA CLARA, CA 95054 PH: 408 986 – 4300 FAX: 408 986 – 4490
All specifications are subject to change without prior notice.