User Manual Part 2

Theory of Operation 8-5MTX5000 User and Technical Manual
8.3 Outdoor Unit Details
The MTX5000 ODU processes the IF signal from the MTX5000
IDU and generates the higher power microwave signal that is fed
to the antenna. The ODU contains the following components:
• An IF interface module, containing a 2 FSK modem. The
modem communicates with the IDU modem to send and
receive alarms and operating data.
• A power supply, which converts the 12 VDC from the IDU
into +15 VDC, -15 VDC, and +5 VDC for use by the other
RFU modules.
• A UHF up-convertor, which converts the 70 MHz IF signal
to 900 MHz.
• A 3 GHz local oscillator, whose frequency is set by a
control voltage from the interface module (a Voltage-
Controlled Oscillator, or VCO).
• A microwave mixer/up-convertor that mixes the 3 GHz
with the the 900 MHz signal, to produce the frequency
desired. For the 7 GHz and 13 GHz bands, this also
includes a frequency doubler or tripler.
• A bandpass filter to eliminate unwanted frequency
components.
• A Power Amplifier (PA) that amplifies the resulting signal
to the power level desired.
A functional block diagram of the ODU is shown in Figure 8-2.
Figure 8-2: ODU Block Diagram
3 GHz
VCO
POWER
SUPPLY
POWER
AMP
UHF
UPCONVERTER
INTERFACE
BOARD
FSK
MODEM
MICRO
PROCESSOR
FILTER
MICROWAVE
UPCONVERTER
RF OUTPUT
TO
ANTENNA
70 MHz IF +
DC POWER +
CONTROL