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Knowledge Base

Unfit NLP mode cause the voice loss problem when double-talking on MA5600T MSAN

Publication Date:  2012-07-25  |   Views:  201  |   Downloads:  0  |   Author:  Tang Xuan  |   Document ID:  EKB0000577228


Issue Description

When the two subscribers of MA5600T are talking with each other, if one talk, the other listen, the quality is good; but if they both are talking(that is double-talking), the conversation will be incontinuous(some voice is lost).

Alarm Information


Handling Process

If such problem happen on UA, we can just change the oversea parameter to solve it. But on MA5600T MSAN, there is no such oversea parameter, so we can solve it by the following configration:
MA5600T(config-pstnport)#pstnport attribute batset 0/16/0 0/16/31 nlp-mode ?
Command of pstnport Mode:
0:nlp normal mode
1:nlp ecgain mode
2:nlp increased mode
3:nlp reduced mode
4:nlp close mode

MA5600T(config-pstnport)#pstnport attribute batset 0/16/0 0/16/31 nlp-mode

Change to 1,3,4, voice quality can be improved greatly. when setting to1,3 , there is only a little loss and it is the ending part, the subscriber will not feel it. If setting to 4, it means to close the NLP, no any loss. 
In short, problem can be solved when setting to  1,3,4,  in the end, the customer dicide to set nlp-mode to 3.

If we need to change the nlp-mode for all the ports of MA5600T, no need to change it one by one, just use the following command to change by batch:
ma5600t(config-pstnport)#pstnport attribute batset 0/0/0 0/22/63 nlp-mode 3 //From 0/0/0 to 0/22/63, the system will judge which ports need to be changed.
{ |clip-reverse-pole-pulse|dial-mode|line-lock|polarity-reverse-mod
upper-limit|reverse-pole-pulse-level|reverse-pole-pulse }:
pstnport attribute batset 0/0/0 0/22/63 nlp-mode 3
command processing is completed. the data of 96 users has been modified


Currently, no new version can solve this problem, we can only solve it by this setting.

Root Cause

We can adjust the NLP mode to solve this problem, NLP means No-Linear Processor, similar with EC, after EC handling NLP will judge the current voice power of echo, if the power is lower than some special value, it will regard as mute mode. As a result, some voice is lost, and the conversation will be incontinuous for subscribers. We can try to reduce or close the NLP mode.