Huawei IAD108A User Manual page 274

User Manual
U-SYS IAD108 Integrated Access Device
the buffer value of echo cancellation. Its value range is 0 to 15, and 8
ms is a level.
II.
Adjusting Receving/Sending Gain
Normally, the echo problem can be solved after the above
parameter adjustments. If the echo or cut voice (intermittent
communication) remains, you need to adjust the gain on the two sides.
This problem is caused by improper gain settings which affect EC.
The basic principle for gain adjustment is that the different
between the sending gain of the TG and that of the IAD should be as
little as possible. In this way, the EC intermittence can be reduced.
Generally, we recommend the following settings:
Sending gain and receiving gain of the TG be both set to
0db.
Sending gain and receiving gain of the IAD be set to –3.5
and 0 respectively.
Carry out the mg system-parameter command to adjust the IAD
gain. The gain is parameters 3 and 4 (parameter 3 is the DSP input
gain, while parameter 4 is the DSP output gain).
Carry out the modify ipp-ch command to adjust the TG gain.
Parameters 14 and 15 should be modified. The method to modify the
gain is as follows:
1) The size of the gain is adjustable from -14 dB to +6 dB. The
variation step is 0.1 dB. If the step is set to 1, the adjustable
gain range is from -140 to +60. To avoid negatives, set its
value range as from 0 to 200.
2) The relationship between the gain parameter set by the
subscriber and the actual gain is: actual gain = (gain
Chapter 8 Troubleshooting
8-18