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3.3 CDU
3.3.1 Functions
The CDU has the following functions:
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The CDU uses the bridge combiner (broadband combiner) with 3 dB power loss to enable
multiple transmitting signals and receiving signals to share the same antenna unit. In practice,
the mode of transmitting 2-in-1 or receiving dual channel 1-into-4 (or single channel 1-into-8)
can be adopted. In addition, CDU also has a diversity receiving tributary.
The CDU supports the GSM900, the GSM1800, the GSM1900, and the GSM850 frequency
bands. The maximum input power of its single port is 60 W.
3.3.2 Structure and Principle
The CDU has multiple panel types, but the structure and the principle of the CDU are the
same in any cases.
Figure 3-4
3-6
"X" means that the status of switch (ON/OFF) has no relation with the DIP switch function.
S2 is not allowed to be set to any other status apart from the above two.
Combining and filtering of transceiving duplex
Transmitting signals
Filtering of receiving signals
Amplifying the low-noise
Dividing of receiving signals
Providing the TMA feeding.
shows the structure of the CDU.
Huawei Technologies Proprietary
M900/M1800 BTS3X Series Base Transceiver Station
Hardware Description Manual
Issue 01 (2006-11-18)
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