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User Manual
Airbridge cBTS3612 CDMA Base Station
RXAM-TEST
RXBM-TEST
DC-IN
PWR
S/W
DB15
Figure 2-20 Structure of RLDU
1) Receiving signal low noise amplification and distribution unit
There are 4 LNAs and distributors inside RLDU, which can process 4 signals. The 4
LNAs have the same specifications such as gain, noise factor and dynamic, so the 4
receive paths are balanced.
2) Configuration switch unit
The electronic switches inside RLDU are designed for supporting different BTS
configurations. When the BTS is configured in 3-sector mode, the electronic
switches can be set to make RLDU operate in a single-sector mode that has two
main/diversity receiving paths (Each path provides 1 -in-4 output to support 1~4
carriers configuration for each sector). When the BTS is configured in 6-sector mode,
the electronic switches can be set to make RLDU operate in two-sector mode each
of which having 4 main/diversity receive paths (Each path provides 1 -in-2 output,
supporting 1~2 carriers configuration for each sector).
3) Antenna VSWR and LNA status monitoring unit
The transmitted forward/reverse power coupling signals from CDU or DFU or DDU
are processed in the antenna VSWR monitoring circuit inside RLDU. When the
VSWR of transmitting antenna exceeds a specified threshold, alarm will occur. At
the same time, RLDU also converts transmit coupling power signal into DC level
signal through its RF power detecting circuits. Through this DC level signal, any
Switch distribution
LNA
module
module
Power supply
VSWR check processing
Forward power output
2-38
2 Hardware Architecture
VSWR and power
check
System Description
RXBD-IN
RXBM-IN
RXAD-IN
RXAM-IN
APf-IN
APr-IN
BPf-IN
BPr-IN
RXAM1
RXAM2
RXAD1
RXAD2
RXAM3/RXBM1
RXAM4/RXBM2
RXAD3/RXBD1
RXAD4/RXBD2
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