IBUC Operation Manual
Terrasat Communications, Inc.
Rev. A
7-22
Ensure that the TX output power is disabled to prevent accidental transmission
interference with adjacent satellites or transponders before attempting to align or
performing any other operation involving the ODU. Before attempting any system
change, carefully evaluate the possible effects of the transmitted signal.
Setting the TX and RX Frequencies
All transmit and receive frequencies are set in the modem.
For a direct connection to an L-band modem follow the manufacturer’s instructions on
setting the transmit and receive frequencies.
Receive L-band Output Measurements
To check the Receiver, perform the following:
- Ensure that 15-24VDC (LNB Bias) is present at the Rx 1+1 Interface Module RX
inputs A and B.
- Use a spectrum analyzer to ensure that the10MHz signal is present at the modem
RX input.
Warning; DC power will be present on the cable so the use of a DC block is
recommended.
- Connect the Rx 1+1 Interface Module to the demodulator RX input by attaching the
coaxial cables from the RX L-band OUT (J6) on the Interface to the demodulator RX
L-band input port.
Antenna Alignment
WARNING: WHEN ALIGNING THE ANTENNA, THE IBUC MUST NOT
TRANSMIT.
Ensure that the desired transponder is in operation. To find the satellite and peak the
receive signal, perform the following:
- Apply power to the Rx 1+1 Interface Module.
- Sweep the antenna through previously determined azimuth and elevation
adjustments. Note: This must be done very slowly in order to locate the satellite.
- Simultaneously, monitor the RECEIVE signal level at the demodulator. Wideband
signals such as video carriers are easiest to find and should be used when available.
- Tune the antenna and adjust its polarization according to the antenna
manufacturer's instructions until the satellite is found.
TX Power Alignment
Transmit L-band Input Adjustment with Modem or Converter
Warning; DC power may be present on the cable so the use of a DC block is
recommended when performing the following steps.
To set the power level of the modulator output:
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