50
A30808-X3247-L14-2-7618
Technical Description (TED:BSS)
BS-240/241
Information
Base Station System
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.
Fig. 4.6
DIAMCO
Antenna 0
Rx
RXCA
to Rx
Control
CAN bus
DC interf.
TMA
DC/DC
TMA
Signall.
Antenna 1
to/from core
Rx
RXCA
to Rx
LNA
AMCO
MUCO
LNA
LNA
AMCO
MUCO
LNA
BIAS
TEE
BIAS
TEE
Module 0 Module 1