Technical Manual
Airbridge BTS3612A CDMA Base Station
System Principle
Chapter 2 Baseband Subsystem
2-3
Power supply
module
External
communication
module
Clock
module
Backplane
bus module
Other
functional
units
CPU
module
BCKM
..
.
Satellite
signal
receiver
BASB
BASB
Figure 2-2
Structure of BCKM module
The BCKM comprises the following parts:
I. Clock module
Clock module is the clock source of BTS, which provides working clock for various
boards.
Clock module supports two work modes: External synchronization mode (locked mode)
and free oscillation mode (holdover mode). In the former mode, it receives
GPS/GLONASS clock signals through its satellite signal receiver. In the latter mode, it
provides clock reference through high precision oscillator (oven control & voltage
control oscillator).
For the introduction to satellite signal receiver, see “4.3.5 Receiver”.
II. CPU module
CPU module controls logical circuits to initialize relevant components. The
management and control of BTS system is implemented through its system software,
which includes main control software and operation & maintenance software. For
specific function, see ”2.1 Overview”.
III. Backplane bus module
The communication port of the Central Processing Unit (CPU) is connected with other
boards of BTS through the backplane bus module, and processes or transmits O&M
signaling from other boards of BTS (BRDM, BCPM and BCIM).
IV. External communication module
External communication module utilizes the multiple communication control ports
provided by the main control CPU to implement functions such as maintenance
