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<h1>Rx Antenna Supervision by Comparing RSSI Value</h1>

<p>The purpose of this feature is to monitor the Rx antenna
condition. Rx antennas can be monitored for major problems by taking a long-term
average of the difference between the Main Rx RSSI and Div Rx RSSI (Received
Signal Strength Indication). This feature provides continuous antenna supervision
for the BTSs, which have main and diversity in use. It also offers an alternative
solution for Tx monitoring in cells that use duplexing. This detects antennas
with poor VSWR and inadequate feeders, for example.</p>


<p>The monitoring is based on the principle that all received
bursts, where the Rx level of main or diversity branch is above the defined
limit value (-100dBm), are accepted as samples and used in the averaging process.
The differences of the TRXs connected to the same antennas are counted up,
and the average difference per main and diversity antennas is calculated.
If the difference is above the threshold (the default value is 10 dB), an
alarm will be activated. For a PrimeSite, the Rx branch difference is calculated
separately per TRX. The threshold default value of 10 dB can be changed by
a parameter at the BSC between 3 - 64. To disable the functionality of the
feature, use the maximum value.</p>


<p>It is still possible that both antennas are damaged simultaneously,
and the difference algorithm cannot detect the fault. For this reason, the
BTS also observes the assignment and handover success rate per antenna. For
the Talk Family BTS, excessive failures trigger the antenna test, and if necessary,
an SWR alarm is raised. For an UltraSite, a bias T unit detects excessive
failures, and an SWR alarm will be raised.</p>


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