Alcatel-Lucent 9500 MXC, User Manual, Page: 304 / 916

Chapter 5. Antenna Alignment
Vol. III-5-4 Alcatel-Lucent
RSSI/RSL Accuracy
When checking RSSI/RSL against the predicted link values ensure appropriate
allowances are made for Tx power-setting accuracy, path-loss calculation
accuracy, and RSSI/RSL measurement accuracy.
• For a worst-case the overall accuracy is the sum of the individual accuracy
limits, which for an ODU 300 link would be ± 4 dB of the predicted value (±
2 dB for transmit, ±2 dB for receive, 0 to 35C), aside from the path-loss
calculation accuracy, which should be within limits of ±3 dB.
• Typically, where the measured RSSI/RSL is more than 4 dB lower than the
expected receive level you should check the path survey results, path
calculations and antenna alignment.
• A discrepancy of 20 dB or greater between the measured and calculated RSSI/
RSLs suggests an antenna is aligned on a side lobe, or there is a polarization
mismatch.
Aligning the Antenna
Antenna alignment involves adjusting the direction of each antenna until the
received signal strength reaches its maximum level at each end of the link.
Fine adjustment for azimuth (horizontal angle) and elevation (vertical angle) is
built into each antenna mount. Adjustment procedures will be provided with each
antenna.
If the horizontal adjuster does not provide sufficient range to locate the main
beam, the antenna mounting brackets will need to be loosened and the antenna
swivelled on its pole mount to locate the beam. Before doing this ensure the
horizontal adjuster is set for mid-travel. Some mounts for larger antennas have a
separately clamped swivel base to allow the loosened antenna to swivel on it
without fear of slippage down the pole. Where such a mount is not provided a
temporary swivel clamp can often be provided using a pair of pipe brackets
bolted together immediately below the antenna mount.
Refer to:
• Standard Alignment Procedure
• Additional Procedures for a Protected Link
• Additional Procedures for CCDP XPIC links
When checking RSSI/RSL ensure the measurement is made under normal,
unfaded and interference-free path conditions.