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Technical Manual
Airbridge BTS3612A CDMA Base Station
The BTRM also receives the management and configuration information from the
BCKM, and reports the status and alarms of itself to the BCKM.
3.2.2 Structure and Principle
The BTRM consists of BTS Intermediate Frequency Module (BIFM) and BTS Radio
up-down Converter Module (BRCM). Its structure is shown in Figure 3-2.
BIFM
BHPA
BRDM
+24V
PSU
Figure 3-2 Structure of BTRM
I. BIFM
The BIFM consists of up-converter, down-converter, multiplexer/demultiplexer, optical
interface, clock, CPU, and power supply sub-unit. It is in charge of the conversion
between the analog intermediate frequency signal and the digital baseband signal, and
the control of the BTRM. The functions of each sub-unit are as below:
Up-converter
The up-converter accomplishes the wave filtering, digital up-conversion and
digital-analog conversion of the signals in the transmit path.
On receiving the baseband I/Q signals that have been de-multiplexed, the up-converter
performs digital up-conversion after baseband filtering. Then the digital intermediate
frequency signals are converted into analog intermediate frequency signals after
digital-analog conversion and wave filtering. At last, the analog intermediate frequency
signals are sent to the transmitter in BRCM via radio frequency (RF) interface.
Down-converter
The
down-converter
down-conversion and baseband filtering of the signals in the receive path.
CPU
Down
ADC
FIR
converter
&
Down
DAGC
ADC
converter
FIR
Up
&
DAC
converter
DAGC
Power
accomplishes
3-3
Chapter 3 Radio Frequency Subsystem
BRCM
Main receiver
Clock
Filter
Diversity receiver
Filter
Local oscillator
Filter
Transmitter
the
analog-digital
System Principle
RLDU
RLDU
BHPA
conversion,
digital
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