Broadcast Microwave Services Inc TCIIAD-2 Manual Do Utilizador
4
Outdoor Unit
A simplified block diagram of the ODU is shown below:
IF Input from IDU
(70 MHz) Type ‘N’
(70 MHz) Type ‘N’
Power Supply
+48VDC
Cable
Telemetry
Controller
N-plexer
L.O.
70 MHz
L.O.
RF output to Antenna
Power
detector
Cable
compensation
Type ‘N’
Temp Sensor
Microwave upconverter
UHF upconverter
Aux I/O
Ant relay
Feed Pol
TCII Outdoor Unit
Figure 3 TCII Outdoor Unit (ODU) Block Diagram
The ODU is mounted outdoors and connected to the IDU by a single coaxial cable.
The ODU is in constant communication with the IDU via a telemetry channel that is frequency multiplexed
onto the single cable interface between the IDU and ODU. This channel is used to configure the ODU
(select frequency, power level etc) and also to monitor performance (PLL lock, temperature etc). A
microcontroller within the ODU handles this communication and controls the respective parts of the ODU.
onto the single cable interface between the IDU and ODU. This channel is used to configure the ODU
(select frequency, power level etc) and also to monitor performance (PLL lock, temperature etc). A
microcontroller within the ODU handles this communication and controls the respective parts of the ODU.
The 70MHz input is first up-converted to the UHF band and then up-converted again to the desired
operating frequency (a dual frequency conversion scheme allows spurious free operation and full band
coverage). The signal is then amplified and fed to the antenna. A power detector at the transmitter output
helps ensure that the transmitter always operates most efficiently which is particularly important when
transmitting digital COFDM.
operating frequency (a dual frequency conversion scheme allows spurious free operation and full band
coverage). The signal is then amplified and fed to the antenna. A power detector at the transmitter output
helps ensure that the transmitter always operates most efficiently which is particularly important when
transmitting digital COFDM.
The ODU provides connector interfaces to support remote (mast mounted) antenna selection and antenna
feed polarity selection. Four additional contact closures are also provided for user specific applications.
These are controlled by corresponding inputs at the IDU.
feed polarity selection. Four additional contact closures are also provided for user specific applications.
These are controlled by corresponding inputs at the IDU.
A temperature sensor is included in the ODU and can be monitored on the IDU front panel. If the
equipment is operated in extremely hot temperatures the ODU will automatically back off the output power
to preserve operation and prevent damage to the unit.
equipment is operated in extremely hot temperatures the ODU will automatically back off the output power
to preserve operation and prevent damage to the unit.