30
A30808-X3247-L14-2-7618
Technical Description (TED:BSS)
BS-240/241
Information
Base Station System
The COSA6P16 is switched with relays to the PCM-lines. In case of failures, the
PCM-port 1(3)(5) and 2(4)(6) can be connected with each other via appropriate relays.
There is a power-on device on the COSA6P16, which generates a reset at power-on
(board-reset). Via a line, the COSA6P16 can be reset from the COBA (board-reset).
Additionally, single devices on the COSA6P16 can be reset from the COBA via the
SAT-interface.
3.2
Carrier Unit (CU)
The Carrier Unit (CU) takes care for all carrier oriented tasks. In the uplink (UL) direction
two RF signals (diversity) are received and finally converted into TRAU frames and
signalling data. In the downlink (DL) direction, TRAU frames and signalling data are
received and converted into a GMSK modulated RF signal, which is amplified to the
desired power level.
The CU consists of following sub-units:
•
Power Amplifier and Transceiver Unit (PATRX)
•
Signal Processing Unit (SIPRO)
•
Power Supply Unit (PSU)
There are four variants of CU for the frequency bands GSM 850, R-GSM 900, GSM
1800 and GSM 1900. The differences of the variants arise mainly on the sub-unit
PATRX.
Fig. 3.5
Carrier Unit Block Diagram
Power Amplifier and Transceiver Unit (PATRX)
PATRX provides the main analogue functions of the CU:
–
receives the two (diversity) RF signals from the antenna combining equipment and
converts them down to IF. The downconverted RF signals are then transmitted to
SIPRO where they are sampled and digitally downconverted to baseband.
–
receives the GMSK modulated signal from the SIPRO. The signal is then I/Q modu-
lated, upconverted, levelled, power amplified and transmitted to the antenna
combining equipment.
–
supports the synthesizer frequency hopping
–
provides an RF loop between downlink and uplink path for the unit test of the CU
The power control loop implements 6 static power steps (each 2 dB) and additional 15
dynamic power levels (each 2 dB). For low output power versions of the CU, a further
reduction of 2 dB is provided.
SIPRO
PSU
PATRX
CC-Link
-48V DC
Rx inputs
Tx output
Test PC/OMT, SCC,
Layer 1 Trace, JTAG,
PID, Vcce Loop
Display
