User Manual

AS4000 Operations and Maintenance
Section
605-0000-431
6
. Issue 1.6. Date3/2/99
DLP-013
Page 6 of 60 © Copyright Airspan Communications Corporation 1999
7. Connecting Test CRU
The purpose of this test is to enable the RX sensitivity at the CT to be set to -98dBm to
within 1dB. This section provides details of the test set-up for the setting of the RX gain
control.
a) Switch rack off by placing both breakers in the off position.
b) Disconnect terminations on DIP/LNA1 and TX filter.
c) Connect the cables and accessories to the CT rack for Modem Shelf setting up and
functionality testing as detailed in Figure 7-3. Set the 0-11dB variable attenuator to a
nominal value (8dB for 2.0 - 2.3GHz band systems or 7db for 2.3 - 2.5GHz band systems,
the insertion loss of the test circuit should be 109dB between point a and b in Figure 7-3).
In practice the setting of the attenuator will be a few dBs less than the nominal level to
account for the actual cable, connector and splitter loss. Due to the microwave
frequencies involved the commissioning items need to be calibrated for the channel
frequencies to be used.
Note: If the TX Filter is not fitted terminate the port of Splitter A as shown in Figure 7-3.
d) Switch the power back on at the breakers.
Power
Meter
ST
Test
Unit
CT Rack
3
1 2
30dB
30dB
30dB 30dB
2:1
Splitter
2:1
Splitter
2:1
Splitter
SMA-N
RF Sensor
N-SMA
11dB
Variable *
* Set variable attenuator to give an insertion loss of 109dB
between points A and B (nominal value of 8dB for C-Band or
7dB for X-Band)
DIP/LNA TX Filter
RX
TX
NTU
NTU
ACPSU
A
B
If TX Filter not fitted
Terminate port here
Adapter
Female to
Female
C
Figure 7-3. Test Set-Up Modem Shelves (2.0-2.3GHz and 2.3-2.5GHz Band)