ALM-5286 Combining and Distribution Unit VSWR Level 1 Alarm

Description

The alarm is triggered when the VSWR of the jumper side at the CDU antenna port exceeds the level 1 alarm threshold (nominal 1.5). It is triggered not on the port of the diversity receive antenna but on that of the transmit/receive duplex antenna of the CDU.

Attribute

Alarm ID	Alarm Severity	Alarm Type
5286	Warning	Fault

Parameters

ID	Name	Meaning
1	Site No.	Number of the site where the faulty board or module is located Value range: 0-2047
2	Board Type	Number of the type which the faulty board belongs to. C7:P-CDU C9:D-CDU
3	Board No.	Number of the fault board 0:CDU 0 1:CDU 1
4	PassNo	Number of the passage where the faulty board is located.
5	SubLink No.	Alarm sub-category number 255: None
6	Cell Index	Index of the cell where the board or module is located 0-2047: Cell index of the faulty cell in the data configuration 65535: None
7	Site Type	Type of the site where the faulty board is located. 3:BTS30; 5:BTS312; 10:BTS3012A; 11:BTS3006A; 12:BTS3012; 13:BTS3006C; 14:BTS3002E; 15:BTS3012AE; 16:BTS3012 II;
8	RackNo	Number of the rack where the faulty board is located.
9	BoxNo	Number of the subrack where the faulty board is located.
10	SlotNo	Number of the slot where the faulty board is located.
11	Site Name	Site Name
12	Alarm Attribute	Alarm Character 0:Normal 1:Transient Count

Impact on the System

This alarm shows that the antenna feeder system is not well compatible with the CDU antenna port. Much power transmitted from the BTS through the CDU antenna port is reflected by the jumper and feeder. Thus the power of the downlink signals transmitted to the tower top decreases.
Similarly, the uplink signals received by the corresponding antenna feeder branch are also reflected at the CDU antenna port. Thus the power of the signals received by the TRX decreases.

System Actions

None.

Possible Causes

The jumper is not properly connected with the CDU on the antenna feeder tributary.
The feeder (including connector) is damaged.
Such devices on the antenna feeder tributary as the tower top amplifier (TTA) and lightning arrester are damaged.
The antenna is damaged.

Procedure

Check the cable connections.
1. Check whether the connections of jumpers between the CDU antenna port and the feeders are normal.
  Check the connections between the jumper and the duplexer, between the jumper and the feeder, between the jumper and the surge protector, and between the jumper and the antenna.
  
  Y => All the connections are good. Go to step c.
  
  N => A connection is not secured. Go to step b.
2. Tighten the loosened connectors. Reset the CDU and then check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to step c.
3. Check whether the water leaks into the connectors between the jumper and the duplexer, between the jumper and the feeder, between the jumper and the surge protector, and between the jumper and the antenna.
  Y => There is water leakage. Go to step d.
  
  N => There is no water leakage. Go to 2.
4. Shut down the TRX corresponding to the faulty CDU.
5. Replace the connector where water leakage occurs.
6. Turn on the power amplifier of the TRX corresponding to the CDU. Check whether the alarm is cleared.
  Y => The alarm is cleared. Reset the TRX. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to 2.
Check the antenna VSWR.
1. Measure the VSWR by using the related instrument (for example, the SiteMaster) at the antenna port of the CDU. Locate whether the fault occurs on the jumper, surge protector, feeder, TMA, or the antenna. The VSWR of greater than 1.5 is the abnormal value.
  Y => The VSWR is abnormal. Go to step a.
  
  N => The VSWR is normal. Go to 3.
2. Shut down the TRX corresponding to the faulty CDU.
3. Replace the component with the abnormal VSWR.
4. Turn on the power amplifier of the TRX corresponding to the CDU. Check whether the alarm is cleared.
  Y => The alarm is cleared. Reset the TRX. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to 3.
Replace the CDU.
1. Shut down the TRX corresponding to the faulty CDU.
2. Replace the CDU.
3. Turn on the power amplifier of the TRX corresponding to the CDU. Check whether the alarm is cleared.
  Y => The alarm is cleared. Reset the TRX. The alarm handling is complete.
  
  N => The alarm is not cleared. Contact Huawei Customer Service Center.