Siemens BS-240 Technical Description page 50

Technical Description (TED:BSS)
BS-240/241
50
modulated onto a IF carrier at 7.86 MHz: This interface is identical to the interface
between DUAMCO and TMA.
The DIAMCO RX amplifier has two different operation modes, depending on the exist-
ence of TMAs. The first mode is called AMCO mode, the second one is called MUCO
mode. In the AMCO mode where no TMA is used, the DIAMCO gain is around 19 dB.
In case a TMA is used, the DIAMCO is configured in the MUCO mode. In the MUCO
mode, the gain is reduced to about 0 dB. The exact gain of the DIAMCO to compensate
the cable losses can be adjusted for the MUCO mode with a DIP switch. This adjustment
is only done once during the installation of the BTSE by the service personnel. The
selected mode can be read by O&M SW via CAN bus interface.
Due to the fact that TMA status information is available for the DIAMCO processor, the
DIAMCO itself has to switch the RX mode according to the TMA status. Each TMA can
be switched on or off by a separate switch. This cannot be configured via O&M SW!
For Rack Extension the first DIAMCO works in the AMCO mode and the following
DIAMCO sub-modules in the MUCO mode.
The O&M interface of the DIAMCO transmits error messages to the BTS core only via
the CAN bus.
The DIAMCOs are implemented for two different frequency bands: E-GSM 900 and
GSM 1800.
Antenna 0
BIAS
TEE
Rx
MUCO
AMCO
RXCA
to Rx
Fig. 4.6 DIAMCO
Module 0 Module 1
LNA
TMA
Signall.
TMA
DC/DC
Control
LNA
CAN bus
DC interf.
to/from core
Base Station System
Antenna 1
BIAS
TEE
Rx
MUCO
LNA
AMCO
LNA
RXCA
to Rx
A30808-X3247-L14-2-7618
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