IBUC Operation Manual
Terrasat Communications, Inc.
Rev. A
7-23
- With a spectrum analyzer, measure the power level of the L-band signal at the
output of the coaxial cable that connects to the Tx 1+1 Interface Module at J6 (TX L-
band).
- Use the modem or converter level adjust to increase and decrease the power level.
Adjust this for a level of -24 dBm (this will result in rated power at the IBUC output).
- Check that the 10MHz reference signal is between +3 and –12 dBm.
- Disconnect the spectrum analyzer from the coaxial cable.
Transmit RF Output Adjustment with Modem or Converter
To adjust the power level of the IBUC transmitter output:
- Connect a waveguide to coax adapter and a 40dB high power attenuator to
waveguide output.
- Connect the TX L-band input signal to J6 (TX L-band) on the Tx 1+1 Interface
Module.
- Enable the TX signals in the modem or converter and the IBUC’s.
- Measure the RF output with the power meter connected at the waveguide output.
For accuracy measure pure carrier.
- With a Satellite modem: Adjust the RF output to the designated power level
(provided by the satellite network operation center, or its engineering staff) with the
L-band output (modem) level adjust. Do this for both systems (A and B). Equalize
the gains by using the gain setting control of the IBUC’s. There are differences
between the units and cloning doesn’t transfer the attenuator settings from the
Master to Slave.
- Disable the TX signal in the modem or converter.
- Disconnect the TX L-band input signal.
- Remove the waveguide to coax transition and install the transmit waveguide section
to the antenna transit feed.
- Once the transmit input and output power levels have been set, begin transmitting
by connecting the TX L-band input signal to J6 on the Tx 1+1 Interface Module and
enabling the TX in the modem or converter.
- Under the guidance of the Network Operations Center (NOC), fine adjust the
transmit power for the desired down link margin at the receiving station by adjusting
the TX L-band output level adjust (modem or converter output).
Final Checks
To ensure optimum operation, inspect the system for crimped or pinched cabling. Make
sure all connections are secure. Once the system has been aligned and is operating
satisfactorily, it will require a few infrequent and simple maintenance procedures as
described in Maintenance and Service, chapter 5.
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