Technical Manual
Airbridge BTS3612A CDMA Base Station
Forward/reverse coupled RF signals, which are sent to RLDU via the blind mate
connector on the backside.
Forward/reverse coupled test signals, which are output through the standard SMA
connector on the front side of CDU.
3.5.4 Indices
Number of combined signals: 2
Supported frequency band: 450MHz, 800MHz, and 1900MHz.
Module dimensions: 450mm%100mm%344.8mm (Length % Width % Depth)
3.6 DFU
3.6.1 Overview
The Duplexer Filter Unit (DFU) accomplishes the following functions:
Isolating and filtering the transmitting and receiving signals for the single carrier.
Filtering the diversity receiving signals so as to suppress out-band interference.
Key parts of DFU include low-pass filter, duplexer, filter and directional coupler.
3.6.2 Structure and Principle
The DFU structure is shown in Figure 3-6.
RXD-OUT
TX
RXM-OUT
Pf-OUT
Pr-OUT
LPF: Low Pass Filter
Figure 3-6 Structure of DFU
D
D
D
D
D
D
D-SUB
Chapter 3 Radio Frequency Subsystem
BPF
LPF
DUPLEXER
LPF
LPF
S
SMA-Type
N
N-Type
BPF: Band Pass Filter
3-12
System Principle
S RXD-TEST
N TX/RXD-ANT
TX-TEST
S
COUPLER
TX/RXM-ANT
N
S
RXM-TEST