SM ALFOplus - 9.6 OPTIMIZING ANTENNA ALIGNMENT WITH RX MEASUREMENT

MN.00273.E - 004 127
9.6 OPTIMIZING ANTENNA ALIGNMENT WITH RX MEASUREMENT
When the whole radio link is on, antenna alignment can be optimised. Antenna alignment optimization is
performed depending on the Rx signal power at local and remote equipment and evaluating both local and
remote S/N value maximizing them.
There are two possibilities to see the Rx signal power level:
• through WebLCT interface
• through a voltmeter connected to Auxiliary connector on the ODU (F03608 cable - see Fig.57
).
In order to get the Rx signal power level by means of software, connect the PC to serial input of ALFOplus
(LAN2) and start the communication towards the ODU microcontroller with SCT/WebLCT supervisory pro-
gram.
Into WebLCT is shown in the top status bar (Rx1A=-value dBm) see Fig.73
.
If you’re using a voltmeter the Rx signal power level is available on the auxiliary connector of ODU, the
measurement can be performed with a proper cable (see Fig.57
).
Following this last procedure, the voltage you’re reading with the voltmeter is proportional to Rx power
level, refer to Tab.27
.
Tab.27 - Voltage measured in auxiliary port
Typical Rx signal power level: -40dBm. It is the most important item to optimise the antenna alignment,
but in a situation of interference Rx level can be good, BER acceptable but BER margin low. This means
that when Rx fields will decrease then BER will increase fast. The situation can be easily shown with SCT/
WebLCT software looking at Signal Quality level.
Into WebLCT Software select:
• Equipment menu
• Maintenance
• S/N Meas. card (see Fig.75
)
Refer to the “ALFOplus operator” manual for parameter evaluation.
Received Signal (dBm) Signal Output (V) Error (dB)
-20 4.68 ±5
-30 3.51 ±5
-40 2.34 ±3
-50 1.17 ±3
-60 0 ±3
-70 -1.17 ±3
-80 -2.34 ±3
-90 -3.51 ±5
-100 -4.68 ±5
Formula RSSI=Offset + (Signal/Output)/Slope
Slope (V/dB) 0.117
Offset (dBm) -60