Aviat Networks ECLIPSE EDGE, User Manual

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30 Aviat Networks
Chapter 3. Eclipse Edge Installation
RSL Measurement Guidelines
Interference
The RSSI filter has a nominal 56 MHz bandwidth, which means that depending on
the channel bandwidth used, multiple adjacent channels will be included within the
filter passband. Normally this will not cause a problem as antenna discrimination
(beamwidth) and good frequency planning should exclude adjacent channel
interferers. However at sites where this is not the case, ATPC should not be enabled.
• ATPC operates on the RSL. Any interferer that affects the RSL will adversely affect
ATPC operation.
• Check for interference by muting the Tx at the far end and checking RSSI/RSL at the
local end.
NOTE:
Where there is a measurable adjacent channel RSL, do not use
ATPC.
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.
NOTE:
When checking RSSI/RSL ensure the measurement is made under
normal, unfaded and interference-free path conditions.
• A discrepancy of 20 dB or greater between the measured and calculated RSSI/RSLs
suggests the antenna is aligned on a side lobe, or there is a polarization mismatch.
Aligning the Edge 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.