Installation Instructions

D100300-
Doc. No.
Rev.
Date
D100300-REF
1.02
2012-10-09
Damm Cellular Systems A/S, Denmark
BS411 Base Station
Page 3 of 7
Transceiver, TR412
The TR412 Transceiver is a complete TETRA carrier unit
The TX section contains a linear, low noise transmitter linearized with a Cartesian loop. It can
deliver a peak output power of 60W, giving a nominal output power of 25W TETRA .
Modulation and power control is performed in software of the DSP. The output amplifier is
protected with a VSWR protection circuit and a temperature protection scheme. The forward
and reflected power can be measured with built-in RMS power meters. An RFTL output is
available for Base Station test.
The RX is a double super-heterodyne high dynamic range receiver provided with dual
diversity with separate RX paths all the way to the DSP. The final selectivity, diversity
combination, demodulation etc. is made in DSP software.
The 16-bit micro-controller handles the general control functions of the transceiver, boot of
DSP, O&M communications etc. It also handles the packet mode communication on the
HDLC bus to the BSC412.
All internal frequencies are generated with PLL’s locked to the information coming from the
BSC.
TX Combiner, TC411.
The TC411 is a 4-way TX cavity combiner module used to combine the individual TX outputs
to a single cable.
The TC411 consists of 4 motor-tuned ¼ or ¾ λ TEM resonators. The inputs are provided with
dual circulators with high-power loads, which are able to dissipate the reflected power when
the TX antenna is missing or the cavity is tuned to a frequency not matching the transmitter.
An RF detector is provided on the high-power load used for manual adjustment and alarm
generation.
The TC411 is equipped with the TCC411 TC Combiner Controller with built-in micro-
controller, which controls the motors.
At power-up, the micro-controller initializes the tuning position against a mechanical end stop.
The TCC411 is connected to the O&M UART bus and can be reached with O&M commands
from the BSC412.
TX Filter, TF411.
The TF411 is a high power TX filter, which reduces the radiation in the RX band, and is
connected to the TX antenna socket located on top of rack.
Tower Mounted Amplifier/Duplexer, TMD412.
The TMD412 contains two low-loss highly selective RX filters and two low-noise high
dynamic range amplifiers which amplify the RXA and RXB signals.
The TMD412 also contains a duplex filter, which can be used to combine the TX and one of
the RX antennas to a single antenna. The duplex part of the TMD412 is optimized for low
loss and extremely low inter-modulation distortion. When using the duplex filter option, care
shall be taken not to use TX frequencies generating 5
th
order inter-modulations products in
the RX frequencies