Purpose
The radio frequency splitter (RFS) permits the SATCOM system to operate with more than one antenna. One transmit signal from the radio frequency unit (RFU) enters the RFS. The RFS sends the signal to the class C and class A high power amplifiers (HPA).
Physical Description
The RFS has these properties:
*
Length -2 inches
*
Width -2 inches
*
Height -.75 inches.
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SATCOM SYSTEM -RADIO FREQUENCY SPLITTER
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SATCOM SYSTEM -HIGH POWER RELAY
Purpose
The high power relay (HPR) sends the high power amplifier (HPA) outputs to one of the two high gain antenna systems. The HPR sends the signals to the antenna system nearest to the satellite. The port side-mount beam steering unit (BSU) controls the HPR.
Physical Description
The HPR has these properties:
*
Length -2.5 inches
*
Width -1.9 inches
*
Height -1.25 inches.
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SATCOM SYSTEM -HIGH POWER RELAY
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SATCOM SYSTEM -HIGH GAIN ANTENNA
Purpose
The side-mounted high gain antennas (HGAs) transmit and receive signals.
Functional Description
The HGAs transmit signals from the beam steering units (BSUs). As the signals go through the antenna elements, they align into a thin beam. The antenna transmits this beam to the satellite.
The HGAs receive satellite signals through a 20 element array. The received signals go to the BSUs.
Physical Description
Each HGA has an array of 20 elements in a flush-mounted panel.
The HGA has these properties:
*
Length -32 inches
*
Height -16 inches
*
Thickness -0.4 inches
*
Weight -16 pounds.
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SATCOM SYSTEM -HIGH GAIN ANTENNA
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SATCOM SYSTEM -LOW GAIN ANTENNA
Purpose
The low gain antenna (LGA) transmits and receives radio frequency signals for low speed data link. The low gain antenna operates only if the high gain antenna (HGA) system fails.
Physical Description
The LGA contains a single antenna element. A blade-shaped aerodynamic radome protects the element.
The LGA has these properties:
*
Base length -15 inches
*
Base width -3.75 inches
*
Height -6 inches
*
Weight -2 pounds.
CAUTION: BE CAREFUL WHEN YOU REMOVE THE AERODYNAMIC SEAL WITH THE SEALANT REMOVAL TOOL. DAMAGE TO THE AIRPLANE SKIN CAN OCCUR.
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SATCOM SYSTEM -LOW GAIN ANTENNA
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SATCOM SYSTEM -SATELLITE DATA UNIT FUNCTIONAL DESCRIPTION
General
The satellite data unit (SDU) is the system interface and controller for the SATCOM system. It contains system operation programs.
The SDU has these components:
*
Receiver down-converter
*
Transmitter up-converter
*
Three modulator/demodulators (modems)
*
ARINC 429 input/output (I/O)
*
Audio interface
*
System processor
*
2016 MHz phase locked oscillator
*
10.08 MHz precision oscillator
*
Front panel.
The SDU supplies as many as three voice/data channels. It also connects to the radio frequency unit (RFU). The RFU can supply three more voice/data channels.
Receiver Down-Converter
The receiver down-converter gets radio frequency (RF) signals from the RFU. It changes the RF data to as many as three channels of intermediate frequencies (IF) and sends them to the modems.
Transmitter Up-Converter
The transmitter up-converter gets as many as three channels of IF signals from the modems. It uses an input from the 2016 MHz oscillator to change the IF signals to RF. The SDU mixes the RF output with a 2016 MHz reference signal and sends it to the RFU.
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