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User Manual
Airbridge cBTS3612 CDMA Base Station
Pr1-OUT
Pf1-OUT
TX1
RXM-OUT
Pr2-OUT
Pf2-OUT
TX2
RXD-OUT
Figure 2-19 Structure of DDU
Low-pass filter
l
The low-pass filter is used to suppress the high-order harmonic wave. The low-pass
filter on receive channel also functions to suppress the interference from the
transmit channel.
Duplexer
l
The duplexer is used to isolate transmitting signals and receiving signals, suppress
transmission spurious and reduce antenna quantity.
Bi-directional coupler
l
The bi-directional coupler couples forward/reverse power for RLDU, and monitors
the antenna VSWR.
T-type feed connector
l
This connector receives the RF signals and divides/combines DC feeds, so that the
RF signals and DC go through different channels, realizing the D C supply to the
tower-top amplifier.
III. Interface
DDU is a module shared by the transmitting and receiving paths of the BTS. It has
interfaces with other modules both in the transmitting and receiving paths. Its
external interfaces include a set of 8W8 DB combination blind mate connectors on
the backside, and a set of N -connectors and SMA connectors on the front. The
interface signals include:
D
D
D
LPF
BIAS T
D
LPF
D
D
D
LPF
BIAS T
D
LPF
D
D-SUB
N
COUPLER
DUPLEXER
COUPLER
DUPLEXER
S
N-Type
SMA-Type
2-36
System Description
2 Hardware Architecture
TX1-TEST
S
BIAS T
TX/RXM-ANT
N
RXM-TEST
S
TX2-TEST
S
BIAS T
TX/RXD-ANT
N
RXD-TEST
S
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