MINI-LINKEandEMicro
• The command and control signal up-li nk is an ASK (Amplitude Shift Keying)
modulated signal with a nominal frequency of 6.5 MHz.
• The DC feed is in the range of 45 – 60 V DC (24 – 60 V DC, nominal,
is connected to the MMU)
Similarly, the outgoing signals are multiplexed in t he cable interface: receiving
IF signal and command and control signal down-link.
• The nominal frequency of the receiving IF signal is 140 MHz.
• The command and control signal down-link is an ASK modulated signal
with a nominal frequency of 4.5 MHz.
In addition to the above, the cable interface includes an overvoltage protection
circuit.
3.4.2.2 Control and Supervision Processor
The radio interface sub-unit houses the processor for control and supervision of
the radio unit. The main functions of this processor are described below.
Alarm Collection
Collected alarms and status signals from the radio unit are sent to the indoor
MMU processor. Summ ary status signals are visualized by LEDs on the radio
unit.
Command Handling
Commands from the indoor units are executed. These commands include
transmitter activation/deactivation, channel frequency settings, output power
settings and RF loop activation/deactivation.
Radio Unit Control
In addition to the above, the processor controls the radio unit’s internal
processes and loops.
3.4.2.3 Transmit IF Signal Processing
The transmit IF signal is amplified, limited and demodulated. The demodulated
signal is amplified and passed through a buffer amplifier to the microwave
sub-unit for modulation onto 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 alar m, indicating that the transmitting IF signal
level is too low due to excessive cabl e losses.
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AE/LZT 110 2012 R8C 2002-03-04
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