Recently, this alarm of RF Module Rx Branch RTWP Difference Too High frequently and intermittently appears from some sites, not always comes up, that is to say, sometimes the alarm is coming and sometimes automatically clear before we arrive at the site. Base on the above case, we are facing some difficulty in do troubelshooting for this intermittent alarm. Now I provide the procedure clearance of this alarm for your information and you can usually follow this rule to try to clean this type of alarm. The basic procedure is as follows:
1) swap the RF board between faulty (pending) sector with nomal sector ,generally speaking, slot 0/2/4 and slot 1/3/5 respectively,and check whether the alarm does shift with swapped board or not.
2) check whether the feeder cable does cross or not . 3) check if the VSWR value is much more than 1.4 in faulty sector. 4) replace the Rx cable with new one
The attached file of detailed procedure is also enclosed.
ALM-1309 RF Module Rx Branch RTWP Difference Too High Description The RF module measures the RTWP of the main RX channel and diversity RX channel. This alarm is reported when the difference between the RTWP of the main RX channel and the RTWP of the diversity RX channel exceeds 6 dB.
Parameters Name
Meaning
Alarm Type
Fault
Event Type
Hardware
Cabinet No.
Number of the cabinet that hosts the faulty board
Subrack No.
Number of the subrack that hosts the faulty board
Slot No.
Number of the slot that hosts the faulty board
Board Type
MRRU, WRFU, PRRU, MRXU, MRFU
Faulty Channel
Main branch, Diversity branch
Fault Codes Fault Code
Description
None.
None.
Impact on the System Alarm Severity
Major
Alarm Impact
The demodulation and receive performance of the cell deteriorates. The uplink coverage and capacity are decreased.
System Actions None
Possible Causes External interference exists on the main antenna or diversity antenna. The main or diversity RX channel is faulty. The RX attenuation setting of the RF module is improper. The feeder is faulty, resulting in a high passive intermodulation power of the main antenna.
Procedure 1. Check whether the main or diversity RX channel is faulty.
a. Open the alarm browsing window or run LST ALMAF to query active alarms. Check for ALM-1308 RF Module Rx Branch Abnormal. Y => The alarm is generated. Go to step b. N => The alarm is not generated. Go to procedure 2. b. Clear ALM-1308 RF Module Rx Branch Abnormal according to the related handling suggestions. c. Check whether the alarm is cleared. Y => The alarm is cleared. No further action is required. N => The alarm is not cleared. Go to procedure 2. 2. Check the parameter setting of the RF module. a. Calculate the RX attenuation value of the RF module (RX attenuation value = TMA gain feeder loss). b. Run LST RXATTEN to query the RX attenuation value of the RF module. c. Compare the calculated attenuation value with the queried attenuation value. Calculated value = queried value => Go to procedure 3. Calculated value ≠ queried value => Go to step d. d. Run SET RXATTEN to set the attenuation values on the main and diversity RX channels of the RF module to the calculated RX attenuation values. Go to step e. e. Start the RTWP measurement for durations over five minutes to continusouly monitor the main and diversity RTWP values. Difference between the main and diversity RTWP values lower than 6 dB =>The alarm will soon be cleared. No further action is required. Difference between the main and diversity RTWP values higher than 6 dB => Go to procedure 3. 3. Check whether the external interference exists on the main antenna or diversity antenna. a. Log in to the LMT. Start the uplink frequency scan and check whether the external interference exists. You can judge the interference by checking whether obvious curves exists around the uplink frequency. Y => The external interference exists. Eliminate the external interference. Go to step b. N => The external interference does not exist. Go to procedure 4. b. Log in to the LMT. Start the RTWP measurement for durations over five minutes to observe whether the RTWP value is normal. Y => The RTWP value is normal. The alarm will be cleared in half an hour. No further action is required.
N => The RTWP value is abnormal. Go to procedure 5. 4. Check whether passive intermodulation power of the main antenna exists. a. Log in to the LMT. Start the RTWP measurement to observe the changes of the main and diversity RTWP values. b. Disable the TX channel of the RF module: Run SET TXSW, and select the subrack No. and slot No. of the RRU, and then set the Transmission Unit Switch to OFF. Check whether the main RTWP value is normal. Y => The main RTWP value is normal, which indicates that the passive intermodulation power of the main antenna may exist. Go to step c.N => The main RTWP value is abnormal. Go to procedure 5. c. Enable the TX channel of the RF module: Run SET TXSW, and select the subrack No. and slot No. of the faulty RF module, and then set the Transmission Unit Switch to ON. Check whether the main RTWP value rises. Y => The main RTWP value rises, which indicates that the passive intermodulation power of the main antenna exists. Go to step d.N => The main RTWP value is normal. The alarm is cleared. No further action is required. d. Disable the TX channel of the RF module: Run SET TXSW, and select the subrack No. and slot No. of the RRU, and then set the Transmission Unit Switch to OFF. Remove ANTA of the RF module. Check whether the cables or connectors are corroded, deformed, pressed, in good contact, or there is no water leakage in the connectors. Y => The cable connections are abnormal. Rectify the fault and go to step e.N => The cable connections are normal. Go to step e. e. Reconnect the jumper to the ANT port of the RF module, and tighten the connector.Enable the TX channel of the RF module: Run SET TXSW, select the subrack No. and slot No. of the faulty RF module, and then set the Transmission Unit Switch to ON. f. Query the main and diversity RTWP values for durations over five minutes. Difference between the main and diversity RTWP values lower than 6 dB =>The alarm will soon be cleared. No further action is required. Difference between the main and diversity RTWP values higher than 6 dB => The fault persists. Go to procedure 5. 5. Replace the RF module. a. Replace the RF module. b. Check whether the alarm is cleared. Y => The alarm is cleared. No further action is required.
N => The alarm is not cleared. Contact Huawei.
