Microwave trouble shooting manual

© 2006, ZTE Corporation. All rights reserved.

Microwave Maintenance Experience share

By : Tu Qiang15 Dec 2009


• RX level lower

• IF cable connector problem

• RF cable or HYB problem

• E1 channel alarm

• ODU faulty

• IDU faulty

Ordinary Problem :


• All of these problems can use PNMTj and Multimeter check the alarm; voltage and resistance to confirm.

Ordinary Problem :


• For easily to know how to solve the Microwave problem, this document will according to the parameter and alarm find the problem, and then give the solution.

Parameter and Alarm :


Parameter and Alarm :1: Metering


Parameter and Alarm :1: Metering

The parameter of metering is very important and from the parameter can know link work normal or not.

• TX Power

• RX Level

• ODU Power Supply


1: Metering1-1: TX Power

ODU TX PowerConfiguration: 1+0

• ODU TX Power = TX Power Metering + |MTPC TX Power| (TX Power Metering is the red square; MTPC TX Power in the link

summary can find the value)

• Normal: +20 dBm<= ODU TX Power <= +27 dBm



ODU TX Power <+20dBm 1: Maybe the IF cable connector problem, please check. 2: Check the ODU Power Supply (the red square) is normal or not. 3: After confirm the IF cable connector no problem and ODU Power

Supply is normal, than can confirm the ODU faulty. Contact to the HCPT-MS Regional Manager to arrange the spare part and then change.




There have 2 TX Power, one have value, another one is ***, that is normal, because system is hot-standby.



How to check the IF cable connector• From the L type connector test the resistance, the N type connector

connect to the ODU.• The multimeter select the 200kΩ to test the resistance.

Test Result• Normal18kΩ < ODU resistance < 40kΩ

• ODU resistance=0 or ODU resistance=1 The connector problem, please

remake the connector.



The IF cable connector type

L Type

N Type

The L Type connect to the IDU The N Type connect to the ODU



How to make the IF cable connector



How to check the ODU power supply

1: From PNMTj Metering

• Normal -48V <= ODU Power Supply <= -54V

• ODU Power Supply= 0 Please check the IF cable connector and check the IDU IF interface

voltage.



How to check IDU IF interface voltage

Multimeter select DC 100V

• Normal75 V < Voltage < 85V

• Voltage= 0VThe IDU Faulty, please contact to the HCPT-MS Regional Manager to arrange

spare part and then change.



Actually Case Analyze


• If you perform this link troubleshooting, how to solve this problem?


1: Metering1-2: RX Level

RX LevelConfiguration: 1+0

• Normal -45dBm <= RX Level <= -27dBm




• RX Level too much High: RX Level > -27dBmInform Mr. Tu Qiang to set the MTPC TX Power to make the RX Level in the

normal value.

• RX Level Low: -75dBm <= RX Level <= -45dBm, the link will flicker.1: Check the TX Power of both sites of this link is normal or not, if not normal,

same as chapter 1-1 TX Power, 2: If TX Power normal, check the waterproof of ODU and antenna of both

sites, if not normal, please take picture and inform Mr. Tu Qiang.3: If the waterproof normal, please check the antenna screw is loose or not.4: If antenna screw loose, it need alignment antenna. If urgently case, please

inform Mr. Tu Qiang before perform alignment antenna; if not urgently case, please save the screen copy of the Metering and Link summary, and make the work order send to Mr. Tu Qiang, after approve, can start the alignment antenna.




• Signal lost: RX Level < -75dBm , Link completely down.1: Check the opposite site electric power is normal or not2: If electric power normal, please check the TX Power of both site is normal

or not, if not normal, please refer to chapter 1-1 TX Power.3: If TX Power normal, check the waterproof of ODU and antenna of both

sites. If not normal, please take picture and inform Mr. Tu Qiang.4: If the waterproof normal, please check the antenna screw is loose or not.5: If antenna screw loose, it need alignment antenna. This is urgently case,

please inform Mr. Tu Qiang before perform alignment antenna.



How to perform alignment antenna

• Set the alignment antenna mode on



How to perform alignment antenna

• After setting alignment antenna on, can use multimeter monitor the RX Level from ODU.

• The target of RX Level from multimeter is:

3.0V <= RX Level <= 3.7V



Caution

• Do not set another item “on” in the Maintenance Menu, it will make the service down.

• Do not forget screw the cap on the RX LEV MON of ODU.• Do not climb the tower when the weather is bad, such as rain; strong

wind; lightning; etc.




• No1 RX Level for ODU1• No2 RX Level for ODU2• The RX Level of ODU1 and ODU2 should almost same.• If RX Level not same, and more than 10dBm, please check the less

one ODU IF cable connector; RF cable and HYB.



7/8 GHz ODU Configuration: 1+1RF = Low Loss Cable



11/13/15 GHz ODU Configuration: 1+1No RF cable



Actually Case Analyze

• If you perform this link troubleshooting, how to solve this problem?


Parameter and Alarm :2: Alarm



Color• Green: Normal• Pink: Minor alarm• Red: Major alarm• Yellow: Maintenance

When perform troubleshooting on site, click the red color module to check the alarms.



2-1 Input LOS alarm



2-1 Input LOS alarm

1: Confirm this channel use or not, if not use, no need care about this alarm.2: If this channel use, please check the E1 cable in the DDF.

Sometimes can find the Input LOS alarm flicker, it is the E1 cable not tight in DDF, so please unplug the E1 cable and plug in DDF.



2-2 ODU CPU/Cable Open

Please refer to chapter 1-1 check the IF cable connector.



2-3 RX Level

Please refer to chapter 1-2 RX Level



2-4 LOF (Lost of Frame)

LOF always together with RX Level alarm, after RX Level alarm clear, the LOF alarm will clear.



2-5 High BER

This alarm means this link have high error rate, this case is very complex, the major reason is:

1: RX Level Low2: Interference3: Fade margin4: The grounding not good


THANKS

If you have any problem about MW, please contact with me!

Microwave trouble shooting manual

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