ZXG10 BS21 (V2.2) Compact Outdoor BTS for GSM Maintenance Manual
156
Confidential and Proprietary Information of ZTE CORPORATION
data management by blocking the logic channels. Observe whether
the calls can be made normally and check them in turn until the
faulty ETRM and TCH are located.
ii.
If alarms occur, handle the fault according to the alarm information.
iii.
Otherwise, follow the steps below to eliminate the fault.
¾
Check whether the RF cable between the ETRM and the AEM, and
that between the two-channel receiving signals of ETRM and the
AEM divider output end are normal. If abnormal, please connect
them again.
¾
Reset ETRM. If the problem is not solved, replace the ETRM.
¾
If the ETRM is normal, replace the AEM.
7.
Precautions
None.
MS Echo during Conversation
1.
Symptom
MS echoes occur in conversation.
2.
Source
Faults occur in dialing.
3.
Related parts
Handover parameters, ETRM module.
4.
Fault analyzing and locating
The fault is caused by:
i.
Faults occur at the echo suppressor set between PLMN and PSTN
network.
ii.
Echoes will appear if the TC unit, which implements transcoding
and rate adaptation at the BSC side, goes wrong.
iii.
The transmission circuit of MS goes wrong.
iv.
Echoes can also be caused by the loop from the careless daily
maintenance of the circuits of the A interface and Abis interface.
v.
The voice decoding part in the ETRM module goes defective, which
may also lead to echoes.
