XPIC Troubleshooting

[ahmedze]

Hi Friends,

I would like to know the procedure how to troubleshoot the XPIC Link Like to Find BER,Radio faulty....

Thanks in advance

[jndomingo]

Hi Bro,
I hope your well, In my experienced for testing WORKING SUSPECTED HARDWARE.
-I isolate the link per polarization. Disable the xpic and turnoff the other polarization circuit, letting only one POLARIZATION LINK
-while only one working polarization is enable i will try to conduct IF/RF LOOP to suspected Degraded MMU / Radio and tested back by BER TESTER or IP TESTER.
-for a while I know its a long term process of isolation's but its the only way in my experienced that i can trace a WORKING SUSPECTED Hardware.
(I can only implemented these in maintenance window time for a live traffic link )

I Hope bro, it can help to isolate your case, I will try to search other way around or different approach.

regards

br//

[ahmedze]

Thanks dude for your reply,so it's the same if we have a 1+1 link I think,

[qwertry]

Hi,

You can troubleshoot XPIC link in same way as normal 1+0 link, just turn off transmitters on one of polarizations. First, check antenna alignment in all directions (horizontal and vertical plane, Feed rotation), your receive level must be close to this specified in link design, H vs. V discrimination must be around 30 db and above (depends from antenna model). Regarding BER, leave only one of polarizations to work, monitor link performance on radio link (RAU) level, check also 15min performance intervals. If you have errors on radio link check for interferences or HW fault, if link is error free perform same actions on other polarization. When you have error free link both polarizations you can focus on XPIC settings and checking antennas again. If faulty hardware is suspected, then you can test HW with applying loops. Turn off far-end radio and set RX loop on RAU, near-end must be alarm and error free, receive level in RAU around -50 dbm. In many cases reasons for BER and errors on radio link are external interferences, unfortunately in such case it is hard to troubleshoot any link.

BR

[ahmedze]

Dear Qwerty,

Can you explain me more this phrase:check antenna alignment in all directions (horizontal and vertical plane, Feed rotation), your receive level must be close to this specified in link design, H vs. V discrimination must be around 30 db and above (depends from antenna model)

[qwertry]

Hi,

Check antenna alignment, i suppose that you using HPX antenna, so leave only V pol. link active and turn off H pol. Then check alignment, rotate antenna in horizontal and then in vertical direction to achieve max. receive levels (as on normal link). When antennas are aligned, use digital level to set feed of antenna to 0 deg.,this must be done both at near end and far end. Then check Rx levels on near-end, on far-end only V pol. TX is on. Rotate feed on near-end to achieve 30 db or more difference in RX levels between H and V pol.

BR

[j.ak]

I think the best way to check xpic is to turn off vertical at both ends and measure the rx levels on both horizontal and vertical. The difference between vertical and horizontal should be in between 28 to 33. The more value you get, the best is the xpic. But also it should not exceed 33. And repeat the same with horizontal off and vertical on. If the value doesn't lies between the described value, then you have to adjust the feed.