RX Path Imbalance

RX PATH IMBALANCE Abstract This document describes the troubleshooting procedure for the RX-PATH IMBALANCE alarm .This alarm can be raised due to a number of reasons: Faulty antenna system, not properly connected cables or a faulty CXU (RBS 2X06). The actions in this document should be performed before replacing the CXU (RBS 2X06). Alarm : Fault No. SO CF I2A:57 Fault name RX path imbalance Related faults AO RX I2A:5 – RX path A imbalance AO RX I2A:6 – RX path B imbalance AO RX I2A:7 – RX path C imbalance AO RX I2A:8 – RX path D imbalance AO TX I1B:35 – RX path imbalance SO CF RU:40 – Antenna Troubleshooting : 1. Check that all cables are connected and tighten. If several cells are affected then

maybe two feeders have been switched. 2. Start the OMT and read the IDB 3. Read the Fault Status and monitor the fault, i.e. CF I2A:57, ‘RX Path Imbalance’

4. Check the Define RX Path Imbalance Parameters function in the OMT for the

faulty antenna system. Goto : Configuration  Define  Define Antenna SupervisionAntenna System-X Default Value are :

5.

Start the ‘RX PATH IMBALANCE.’-monitor for each active TRX GO TO : Mainenance  Monitor RX Path Imbalance

Check the RX Path imbalance value for active TRX. If Value < - Class1 & Class 2 Alarm threshold indicates that RX-A signal is faulty. If Value > Class1 & Class 2 Alarm threshold indicates that the RX-B signal is faulty. Monitor value is updated every 5 minutes TRXC-4: RX Path Imbalance: RX imb. superv. values: Supervision window configured time: 1440 min Supervision window elapsed time: 1440 min Average delta signal strength A-B: -10.7dB Number of samples A-B: 11213 100406 15:44:26 TRXC-5: RX Path Imbalance: RX imb. superv. values: Supervision window configured time: 1440 min Supervision window elapsed time: 1440 min Average delta signal strength A-B: -11.2dB Number of samples A-B: 1044254 100406 15:44:46 TRXC-6: RX Path Imbalance: RX imb. superv. values: Supervision window configured time: 1440 min Supervision window elapsed time: 1440 min Average delta signal strength A-B: -10.0dB Number of samples A-B: 378911 100406 15:44:46 TRXC-7: RX Path Imbalance: RX imb. superv. values: Supervision window configured time: 1440 min Supervision window elapsed time: 1440 min Average delta signal strength A-B: -11.9dB Number of samples A-B: 19361

Set the TRUs in local mode and swap the antenna feeder for RX-A and RX-B on the faulty sector. Set the TRUs in remote mode and check the values again for two consecutive readings (approx. 10 minutes) 6. If the values have the same polarity as before swapping the feeders, then it an

be assumed that the fault is within the cabinet. • Check coaxial RX cable from DRU to DRU (2X16) • Check coaxial RX cable from TRU -CDU or TRU-CXU-CDU (2X06) • If all cable is ok, replace CXU (RBS 2X06) If the values change polarity – The antenna system is faulty •

Check the TX cables/feeders, cable connections inside and outside the cabinet and antennas, for example with Antenna System SWR tests.

•

Antenna azimuth and tilt

7. When the fault condition has been corrected, reset the TRU to cause the fault to

terminate immediately. Observe, if the fault condition was not corrected, the fault will be reported again when at least the minimum number of samples has been collected. The minimum number of samples is defined by the Defined RX Path Imbalance Parameters function in the OMT