Ericsson MINI-LINK BAS, Техническое описание, Страница: 67 / 174

5-11 MINI-LINK BAS
EN/LZB 111 0542 P2B Technical Description
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The DC feed for the overall RAU.
Similarly, the outgoing signals are multiplexed in the cable interface:
receiving IF signal and command and control signal downlink.
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The nominal frequency of the receiving IF signal is 140 MHz.
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The command and control signal from RAU to modem is an ASK
modulated signal with a nominal frequency of 4.5 MHz.
In addition to the above, the cable interface includes an over-voltage
protection circuit.
The transmitted IF signal is also used as control signal for the Tx
on/off circuit.
Transmitting IF Signal Processing
The transmitting IF signal is amplified, limited and demodulated. The
demodulated signal is amplified and passed, via a buffer amplifier, to
the microwave transmitter for modulation on to the RF carrier. The
input amplifier is automatically gain-controlled so that no
compensation is required due to the cable length between indoor and
outdoor equipment. The level is used to generate an alarm, indicating
that the transmitting IF signal level is too low due to excessive cable
losses.
Receiving IF Signal Processing
140 MHz receiving IF signal from the microwave receiver is
amplified and fed to the cable interface. Additionally, a portion of the
signal is fed to a calibrated detector to provide an accurate receiver
input level measurement. The measured level is accessible either as an
analogue voltage at the receive signal level test port or as a straight
forward measure, in dBm, through the operation and maintenance
system.
Control and Supervision Processor
The RAU houses the processor for control and supervision. The main
functions of this processor are:
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Alarm collection
Collected alarms and status signals from the RAU are sent to the
indoor processor. Summary status signals are visualised by LEDs
on the RAU
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Command handling
Commands from the indoor units are executed. These commands
include transmitter activation and deactivation, channel frequency
settings, output power settings and RF-loop
activation/deactivation
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RAU control
In addition to above, the processor controls the RAU’s internal
processes and loops.