Loss of Tracking

OPERATING INSTRUCS

4/1543-CRX 901 47/1 Uen L

Copyright

Copyright Ericsson AB 20012008. All rights reserved.

Disclaimer

No part of this document may be reproduced in any form without the writtenpermission of the copyright owner.

The contents of this document are subject to revision without notice due tocontinued progress in methodology, design and manufacturing. Ericsson shallhave no liability for any error or damage of any kind resulting from the useof this document.

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Contents

Contents

1 Overview 1

1.1 Description 1

1.2 Prerequisites 2

2 Procedure 3

2.1 Analyzing the Alarm 3

2.2 Verifying and Replacing the Board 4

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Loss of Tracking

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Overview

1 Overview

This instruction concerns alarm handling.

1.1 Description

The alarm is a primary alarm. It is issued by the MO, Synchronization.

The alarm is issued if the system or radio clock enters loss of tracking modein a Timing Unit (TU). The value of the attribute, syncRefStatus is changedto LOSS_OF_TRACKING. Normally, the fault must be attended to on site.

The following consequences can occur:

If the system clock is duplicated in the node and if only one TU enters theloss of tracking mode, the syncRefStatus of the reference is changedto LOSS_OF_TRACKING, but it remains active. The system clock qualityis not affected.

The clock quality is not affected when a stand-by reference is available,that is, the clock maintains locked mode by selecting a stand-by reference.However, the alarm stays active as long as any synchronization referencemarked LOSS_OF_TRACKING remains.

If no stand-by synchronization references are available, the fault can affectthe clock quality to the extent that the requirements for normal operationare not fulfilled. For radio applications, this means that the requiredaccuracy of 50 ppb (parts per billion) is not met. However, the clock isstill distributed in the node.

The fault stops or disturbs the traffic over the Synchronous Digital Hierarchy(SDH) or Plesiochronous Digital Hierarchy (PDH) interfaces. Some slipsor bit errors can occur as the clock is not locked to any timing referenceand it cannot comply with the required accuracy.

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Loss of Tracking

Table 1 Alarm Causes

Alarm Cause Description Fault Reason

Fault Location Impact

The systemor radio clockcannot track asynchronizationreference

The systemor radio clockcannot track asynchronizationreferencebecause thereference hasa very largefrequencydeviation

Fault inconnectedequipment

Synchronizationreference

Traffic disturbance

The systemor radio clockcannot track anysynchronizationreference

The systemor radioclock cannottrack anysynchronizationreference as aresult of a faultyTiming Unit orthe aging of itsoscillator

Hardwarefault

Timing Unit Traffic disturbance

1.2 Prerequisites

This section provides information on the documents, tools and conditions thatapply to the procedure.

Note: See the instructions for replacing the board containing the TU.

1.2.1 Documents

Before starting this procedure, ensure that you have read the followingdocuments:

System Safety Information

Personal Health and Safety Information

1.2.2 Conditions

Before starting this procedure, ensure that the Network Synchronization Planis available.

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urn:x-ericsson:r2:reg-doc:*12446-*:*:*?title=System Safety Informationurn:x-ericsson:r2:reg-doc:*12446-*:*:*?title=Personal Health and Safety Information

Procedure

2 Procedure

2.1 Analyzing the Alarm

Perform the following steps at the maintenance center:

1. Examine the value of the attribute, syncRefStatus in the MO,Synchronization, for all defined references.

2. Remove all synchronization references whose state is LOSS_OF_TRACKING.

Configure one (or more, if needed) new synchronization references inaccordance with the Network Synchronization Plan.

Wait at least two minutes to see if the alarm reappears.

If the alarm is not issued again, report the faulty reference to the next levelof maintenance support and exit this procedure. If the alarm is issuedagain, go to Step 3.

3. Examine the value of the attribute, tuSystemClock in MO, TimingUnit,for all timing units in the node. Lock the board that is in state,LOSS_OF_TRACKING, using the instruction, Lock Board. The Lock type isHard Lock.

4. Restart the board, using the instruction, Restart Board. The RestartRankis Cold with Test and the RestartReason is Restart ordered to resolveO&M issues. In the field, RestartInfo, write the name of this alarm, that is,Loss of Tracking.

5. Unlock the board, using the instruction, Unlock Board. Reset theLOSS_OF_TRACKING state, using the action, resetLossOfTrackingin the MO, Synchronization, for all synchronization references. Wait atleast five minutes to see if the alarm reappears. If the alarm is not issuedagain, exit this procedure.

6. Issue a work order based on the instructions for replacing the boardcontaining the TU.

7. Follow the steps described in Section 2.2 on page 4 and continue withthe next step.

8. If the alarm remains, consult the next level of maintenance support. Furtheractions are outside the scope of this instruction.

9. Contact the maintenance center for the remote node to inform them ofthe action taken.

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urn:x-ericsson:r2:reg-doc:*-*:*:*?title=class Synchronizationurn:x-ericsson:r2:reg-doc:*-*:*:*?title=class TimingUniturn:x-ericsson:r2:reg-doc:*1543-*:*:*?title=Lock Boardurn:x-ericsson:r2:reg-doc:*-*:*:*?title=Restart Boardurn:x-ericsson:r2:reg-doc:*1543-*:*:*?title=Unlock Boardurn:x-ericsson:r2:reg-doc:*-*:*:*?title=class Synchronization

Loss of Tracking

2.2 Verifying and Replacing the Board

Perform the following steps at the node:

Note: After all steps involving hardware, wait at least two minutes to see ifthe alarm reappears.

1. The field technician ensures that the board is correctly installed and thatany associated cables are connected.

If the alarm ceases, go to Step 10.

2. The field technician cleans the connections on the board.

If the alarm ceases, go to Step 10.

Note: The cleaning involves disconnecting the cable, using a suitablecleaning kit to clean the connectors and reconnecting the cables.

3. The board is faulty and needs to be replaced. Lock the board.

4. The field technician replaces the faulty board, using the instruction forreplacing the board.

5. Unlock the board.

6. If the alarm is not issued again, go to Step 10.

7. Lock the board again.

8. Put the original board back into the subrack, using the instruction forreplacing the board.

9. Unlock the board again.

10. Return to the procedure, Analyzing the Alarm.

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toc1 Overview1.1 Description1.2 Prerequisites1.2.1 Documents1.2.2 Conditions2 Procedure2.1 Analyzing the Alarm2.2 Verifying and Replacing the Board