Chapter 5. Antenna Alignment
Vol. III-5-16 Alcatel-Lucent
14. View the XPDs on all RACs at both ends of the link to confirm that the spread
of XPDs is similar to that confirmed using the primary transmitters.
• If any fine tuning of feedhead alignment is done with the transmitters locked
to secondary, go back and recheck with the transmitters locked to primary.
• Never adjust the feedhead skew angle of the primary reference antenna.
15. On completion ensure feedhead bolts are correctly tightened - check that
XPDs do not change during tightening.
16. Retain feed-head adjustment data for the commissioning records.
Example Link
An example CCDP space diversity link is illustrated in Figure 5-2.
Site X shows the physical interconnections of XPIC and ODU cables.
If antenna 1 is nominated as the reference antenna for feedhead skew-angle
alignment, the feedhead alignment process can be summarized as:
• With all transmitters locked to primary, adjust the feedhead alignments on
antennas 3 and 4 for maximum RAC XPDs. Where necessary optimize to
provide best (minimal) XPD spread. The spread should be within 2 dB
providing RSLs are within 1 to 2 dB.
• Adjust the feedhead alignments on antenna 2 for maximum secondary RAC
XPDs, and check against the RAC XPDs for antenna 1. Where necessary
optimize the feedhead of antenna 2 only to provide best (minimal) XPD spread
at site X. (Never adjust the feedhead alignment of the reference antenna,
antenna 1).
• Check the spread of XPDs is similar between both ends of the link, sites X and
Y.
• Lock all transmitters to secondary and check that all RAC XPDs are similar
(nominally with 2 dB) to the XPDs obtained under primary Tx operation.
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