msm7719-01 Oki Semiconductor, msm7719-01 Datasheet - Page 39

• Manufacturer Part Number: msm7719-01
• Description: Echo Canceler With Adpcm Transcoder
• Manufacturer: Oki Semiconductor

¡ Semiconductor
Resetting of Echo Canceler Coefficient
In cases where an echo path changes, the echo canceler may be slow in converging. In such cases,
resetting the coefficient of the echo canceler can force it to converge immediately.
In addtion, if the echo path changes after the coefficient is reset, the echo canceler may again be slow
in converging.
There are four resetting modes available, as shown in the table below. If an echo path changes,
execute coefficient reset both by LDCL/ADCL and by LCCL/ACCL pin control (Reset 3) whenever
possible, because resetting by both of them do not affect any echo path state.
Notes on Data Communication
Use the following setting when making data communication:
For 4-bit (32 kbps) data communication:
DTHR=“1” (common to handsfree communication mode and line echo canceler expansion
mode)
Notes:
1. The MSM7719 does not support 8-bit (64 kbps) data communication.
2. Data dropouts or a data error of a few SYNCs occurs upon switching between data
3. Of the voice data through modes, ATHR and LTHR converts PCM data “7Fh” into “FFh”.
No reset (LTHR/ATHR)
Reset 1 (LDCL/ADCL)
Reset 2 (LCCL/ACCL)
Reset 3 (both LDCL/ADCL and LCCL/ACCL)
communication and voice communication.
Control
Echo Convergence Time
Slow
Fast
Degree of Effect
on Echo Route
Significant
No effect
MSM7719-01
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