Alcatel-Lucent 9500 MXC User Manual page 314

Chapter 5. Antenna Alignment
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Regardless of which RAC is online (primary or secondary) all RACs can be accessed to provide RSL/
RSSI/XPD data.
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Up to four CT screens can be displayed at once. These may be from the same INU (same IP address) or
from different INUs (or IDUs).
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• Links are operating error-free.
Where there is potential for interference from other links in the same
geographical area, check by turning the far end transmitter(s) off and measuring
the local end RSL on both V and H feeds.
4. Use the cross pole discrimination (XPD) measurement provided in the
Performance screen for RACs to measure the actual V and H signal
discrimination from each antenna.
• Where measured XPDs are better than 25 dB no further adjustment is
needed.
• Where less than 25 dB proceed to the next step.
The alignment procedures listed under steps 1 and 2 should result in a
discrimination of better than 25dB, as measured in the Diagnostics >
Performance screen for each RAC 40, which is comfortably within the operating
limits of XPIC. However, for best results and greater operating margins during
fading, feedhead alignment should be optimized using the following procedure.
5. Optimize Feedhead Skew-angle Alignment
This procedure corrects for any minor rotational alignment between
antennas at each end.
One antenna is the reference antenna and its feed-head assembly is not
adjusted during this procedure.
If all antennas are adjusted and re-adjusted there is potential for progressive
misalignment to occur. Select one antenna as the reference antenna.
On long hops and where fading is prevalent there is potential for the V and H
plane paths to be affected differently and to therefore exhibit variable
cross-polarization discrimination. This alignment procedure must be conducted
during periods of known, stable path conditions.
6. Lock all transmitters to primary. The receivers can be left as Auto/Lock Off
7. Determine which end of the link is to provide the reference antenna, and at the
opposite end open windows to the CT performance screens for all four RACs.
Adjust the screen size and position of each so that you can see the Cross Pole
Discrimination measurement from all RACs
For example, in Figure 5-2, if antenna 1 is the reference antenna, open
windows to the performance screens for the primary RACs connected to
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