ALM-2274 CDU 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 15). 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
2274 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 or module is located

3: BTS30

5: BTS312

10: BTS3012A

11: BTS3006A

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 jumper is not well connected with CDU antenna port. Much power transmitted from the BTS through the CDU antenna port is reflected by the jumper. Thus the power of the transmitted signals to the tower top amplifier decreases. Similarly, many signals the antenna feeder tributary receives from the antenna are also reflected at the CDU antenna port. Thus the power of the received signals to the TRX decreases.

System Actions

None.

Possible Causes

  • The CDU is not properly connected with the jumper 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.
  • The CDU alarm circuit is faulty (false alarm).

Procedure

  1. Check jumper connections

    Turn off the power amplifier of the TRX corresponding to the CDU. Check whether the jumpers between the CDU antenna port and the feeder are securely connected.

    NOTE:

    Turn off the power amplifier of the TRX corresponding to the CDU to stop power transmission before disconnecting the jumpers between the CDU output port and the TRX input port.

    Y=> Go to Step 2.

    N=> Secure the jumper connectors to the ports.

  2. Measure the VSWR at the CDU antenna port

    Measure the VSWR of the jumper side at the CDU antenna port using a sitemaster or another meter with the similar function. Check whether the measured VSWR exceeds the level 1 alarm threshold (nominal 1.5).

    Y=> Further measure the VSWR of the antenna feeder tributary, including the jumpers, lightning arrester, feeder and antenna.

    N=> There might be a false alarm. Replace the CDU and go to Step [3].

  3. Check whether the alarm is cleared

    Secure the jumper connectors to the CDU output port and the TRX input port. Turn on the power amplifier of the TRX. Check whether the alarm is cleared.

    Y=> The alarm handling ends.

    N=> Contact Huawei Customer Service Center.

    note:

    This alarm might become CDU VSWR Level 2 Alarm. Please observe it carefully.


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