Manual Part 5

ASU
4 Function Description
The general function of the ASU is to take a p ortion of the RX signal and send it
to the co-sit ed RBS.
The ASU also switches the attenuation accord ing to whether or not a Tower
Mounted Amplifier (TMA) is used. It also indicates t he attenuatio n state through
an indicat or.
Coupler 1
Coupler 6
Coupler 2
Coupler 3
Coupler 4
Coupler 5
Atten.
control
DC/DC
converter
CXU-RX1 (CDU1)
CDU1-RX1
CXU-RX2 (CDU1)
CDU1-RX2
CXU-RX1 (CDU2)
CDU2-RX1
CXU-RX2 (CDU2)
CDU2-RX2
CXU-RX1 (CDU3)
CDU3-RX1
CXU-RX1 (CDU3)
CDU3-RX2
+ 24 V
Ant. S1
Ant. S2
Ant. S3
Ant. S4
Ant. S5
Ant. S6
TMA
No TMA
P008480A
Figure 1 ASU Block Diagram
4.1 RX Signal Path
The RX signal path is fed from the antennas through the feeders to the
Antenna Reference Point (ARP). The signal is then filte re d and amplified in the
Combining and D istribution Unit (CDU). From the RX output of the CDU, the
sign al is fe d to the ASU where a small portion of the signal is fed to the RX input
of the co-sited RBS. This is shown in the figure below.
4 (8)
E
N/LZT 720 0232 Uen R2A