*
Sends control data to the phase shifters

*
Controls the high power relay (HPR) (from the port BSU only)

*
Selects the active LNA/DIP

*
Monitors BITE for the LNA/DIP.

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SATCOM SYSTEM -BEAM STEERING UNIT AND HIGH POWER RELAY FUNCTIONAL DESCRIPTION

Operation
The BSU processor -I/O module receives antenna-pointing data from the satellite data unit (SDU) to control the phase shifters. The phase shifters change the phase of the transmit signals. The power dividers divide the RF input of the BSU and give RF input to each phase shifter. The output of the phase shifters drives each of the 20 antenna elements in an HGA to form a narrow transmit beam.
The port BSU also controls the HPR to send the RF from the HPA to the LNA/DIP that is on.
In receive operation, the receive signals from the antenna elements mix into a single output from the BSU.
The port BSU controls the operation of the port and the starboard high gain antenna systems. The BSU turns on the antenna system closest to the satellite. It also turns the other antenna system off. The port BSU sends controls signals to turn on the related port or starboard LNA/DIP.
The port BSU sends 15v dc to the HPR. This voltage goes through the contacts of the relay and returns to the BSU as HPR BITE status. This voltage tells the BSU the position of the HPR contacts.
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SATCOM SYSTEM -BEAM STEERING UNIT AND HIGH POWER RELAY FUNCTIONAL DESCRIPTION

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SATCOM SYSTEM -LOW NOISE AMPLIFIER/DIPLEXER FUNCTIONAL DESCRIPTION

General
The low noise amplifier/diplexer (LNA/DIP) increases the strength and filters RF signals.
The LNA/DIP has these parts:
*
Low noise amplifier

*
Diplexer

*
Transmit/receive switch

*
BITE board.

Low Noise Amplifier
The low noise amplifier increases the strength of the received RF signals from the antennas and sends them to the radio frequency combiner (RFC).
Diplexer
The diplexer has two filters, one for the transmit signal and one for the receive signal. In the high gain system, the transmit filter permits signals to pass from the high power relay (HPR) to the beam steering unit (BSU). In the low gain system, the transmit filter lets the signal pass from the high power amplifier (HPA) to the low gain antenna (LGA). The receive filter lets the signal pass from the BSU or from the LGA to the low noise amplifier. The filters prevent signal interference from other components.
Transmit/Receive Switch
The transmit/receive switch connects the diplexer to the LGA or to the BSU. In the transmit mode, it receives the RF signal from the transmit filter in the diplexer and sends it to the LGA or to the BSU. In the receive mode, it receives the RF signal from the LGA or from the BSU, and sends it to the receive filter in the diplexer.
BITE Board
The BITE board monitors the LNA/DIP on/off signal. In the high gain system, the LNA/DIP gets this signal from a BSU to turn on or turn off the LNA/DIP. Only one BSU and one LNA/DIP pair operate at a time. In the low gain system, the satellite data unit (SDU) sends the LNA/DIP on/off signal. The BITE board also monitors the amplifier current and sends failure data to the BSU or to the SDU.
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SATCOM SYSTEM -LOW NOISE AMPLIFIER/DIPLEXER FUNCTIONAL DESCRIPTION

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SATCOM SYSTEM -HIGH POWER AMPLIFIER FUNCTIONAL DESCRIPTION

General
The class A and class C high power amplifiers (HPAs) increase the signal strength of the RF signals and send them to the high power relay (HPR) or top low noise amplifier/diplexer (LNA/ DIP).
The class A HPA increases the signal strength for the high gain antenna transmit signals. The class A HPA can process many channels at the same time for data link and voice operations. The class C HPA increases the signal strength for the low gain antenna transmit signals. The class C HPA can only process a single channel at a time.
An HPA has these parts:
*
RF assembly

*
Input/output (I/O) processor

*
Thermal monitor.

The example shows a typical class A or class C HPA.
　
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