Siemens BS-240 Technical Description page 48

Technical Description (TED:BSS)
BS-240/241
BIAS
TEE
MUCO LNA
AMCO
RXCA
to Rx
Fig. 4.4 DUAMCO 8:2
48
Antenna 0
Module 0
ASU
Rx Tx
Coupler
LNA
RF Power Combining / Tuning Modes
The low loss power addition is carried out by combining the outputs of TNFs inside the
FICOM. These TNFs are remotely tuned to the channel frequency of the corresponding
carrier. The minimum number of inputs to be combined is 2. It is possible to combine a
maximum number of 8 inputs by adding 'expansion modules' to the 'base module'.
A TNF is first coarse tuned to the desired channel. If RF power is supplied to the TNF it
automatically performs a fine tuning to ensure the best RF behavior. With this automatic
tuning process, the drift of the passband filter center frequency is compensated.
Therefore, the filter combiner can only be used with baseband frequency hopping, as
retuning of the TNF frequency requires up to 5 seconds. But for a large number of
carriers (6 or 8), baseband frequency hopping has only a negligible disadvantage
compared to synthesizer frequency hopping.
FICOM Modularity
The FICOM functions are carried out by two different types of modules. These are:
– Base module 2:1
– Expansion module 2:1
Each type of module is able to combine 2 carriers. But only the base module has an
output for the completely combined signal (antenna output with 7/16 connector). Addi-
tional there is a test output at every base module. Also, the reporting of the antenna
VSWR status is only done by a base module. The different modules are connected
together by a special RF connection cable.
Module 1
MUCO
TMA
Signall.
AMCO
TMA
DC/DC
Control
CAN bus
DC interf.
RXCA
from
Tx
to/from core
Base Station System
Antenna 1
BIAS
TEE
ASU
Rx Tx
LNA
Coupler
LNA
to Rx
A30808-X3247-L14-2-7618
Information
from
Tx