Security Level: Internal Use
RF Module VSWR Abnormal Alarm Prepared by: Rashidi
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Background l
There are several factors that contributed to this alarm such as: [ VSWR value for the overall antenna system of the respective sector is high (more than 1.5). Digi specifications is below 1.3 [ Distance-to-fault (DTF) shows that VSWR value of the antenna, feeder or connector is high. (antenna below 1.1 and connector 1.07 as per Digi specifications) [ RRU or WFRU for the respective sector is hang.
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VSWR Alarm Verification l If RF module VSWR abnormal
%%DSP VSWR:;%%
alarm occurred, firstly use this LMT command:
RETCODE = 0 Succeed.
DSP VSWR l If the result shows VSWR value
VSWR
more than 15, need to do VSWR and DTF sweep test by using site master.
---Cabinet No. Subrack No. Slot No. TxUnitNo VSWR(0.1)
Master
4
0
0
12
Master
4
2
0
51
Master
4
4
0
11
(Number of results = 3)
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VSWR and DTF Test By Using Site Master l
Firstly, block the local cell of the respective sector by using LMT command: BLK LOCELL
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Use this LMT command to turn-off TX switch: SET TXSW
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Then, check the DTF and VSWR by using Site Master. After the rectification has been done, make sure the VSWR value (marker to peak) for the overall antenna system is less than 1.5
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If so, unblock the local cell by using this LMT command: UBL LOCELL
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Also set Tx Switch back to ON: SET TXSW
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Use this command to confirm the VSWR value from LMT again: DSP VSWR
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If the VSWR value is less than 15, the alarm will be cleared. Finally, check the alarm from LMT and double confirm with RNC Engineer (that operate M2000) %%DSP VSWR:;%% RETCODE = 0 Succeed.
VSWR ---Cabinet No. Subrack No. Slot No. TxUnitNo VSWR(0.1)
Master
4
0
0
12
Master
4
2
0
14
Master
4
4
0
11
(Number of results = 3)
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Reset Board of RRU or WRFU l
If the VSWR value is less than 15, but the VSWR alarm abnormal alarm has been triggered, please reset the board (RRU or WRFU). RST BRD
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Basic Steps of using Site Master
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Firstly, please calibrate the site master in the range of frequency that need to be tested. Make sure the calibration tool (open, short and load) is ready. [ Press START CAL button and follow the instructions until the CAL ON status appeared on left top corner.
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Then, test the Distance-to-fault (DTF) of the antenna system by connecting the jumper to the cable/antenna analyzer port of site master. [ Set the distance. Press FREQ-DIST button and set D1 and D2 value. For example: D1 is 0m and D2 is 50m (total length of antenna system is 50m). [ Set the VSWR value. Press AMPLITUDE button and set bottom and top value. For example: Bottom is 1 (always 1 because the minimum VSWR value is 1) and top is 1.3
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Next, test the VSWR for the antenna system. [ Press MODE button and select VSWR-FREQ menu [ Set the limit. Press LIMIT button, select EDIT and put the value of 1.3 [ Set the VSWR value. Press AMPLITUDE button and set bottom and top value. For example: Bottom is 1 (always 1 because the minimum VSWR value is 1) and top is 1.5 [ Press MARKER button and select Marker To Peak to indicates highest VSWR value from the waveform
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Save the results. [ Press SAVE DISPLAY button and key in the title you want to. (Normally site ID or site name together with the sector)
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