A satellite is a specialized wireless receiver/transmitter that is launched by a rocket and placed in orbit around the earth.
Launching a satellite 22,000 miles into space orbit is an amazing technological feat – keeping it there requires more advanced systems engineering.
Nearly all missions, whether they be military, civil or commercial, use space ground systems for both launch and on-orbit operations.
Today’s satellites are technologically more sophisticated and canreceive and re-transmit thousands of signals simultaneously, from simple digital data to the most complex television programming. They are used for everything from weather forecasting and television broadcasting to internet communications, Global Positioning System (GPS) and defense.
The satellite’s functional versatility is embedded within its technical components and its operations characteristics. A typical satellite has two modules:
- The bus module
- The communication payload
The bus module features a structural subsystem, which provides the mechanical base structure with adequate stiffness to withstand stress and vibrations experienced during launch, maintain structural integrity and stability while on station in orbit, and shields the satellite from extreme temperature changes and micrometeorite damage.
The telemetry subsystem monitors the onboard equipment operations, transmits equipment operation data to the Earth control station, and receives the Earth control station’s commands to perform equipment operation adjustments.
Yet another important subsystem, the power subsystem is where solar energy is converted into electrical energy through solar panels. Satellite solar panels can be pivoted as the spacecraft moves. This way they can always stay in the direct path of the light rays no matter how the satellite is pointed.
However, satellites are usually designed with solar panels that can always be pointed at the Sun, even as the rest of the body of the spacecraft moves around. A tracking mechanism is often incorporated into the solar arrays to keep the array pointed toward the sun.
Nuclear power sources have also been used in several successful satellite programs
The second major module is the communication payload. The payload on a satellite is the equipment that provides the service or services intended for the satellite. A communications satellite payload consists of the communications equipment that provides the relay link between the up- and downlinks from the ground. It’s made up of transponders that receive uplinked radio signals from the antennas of Earth satellite transmission stations.
The radio signals are then amplified, sorted and then directed through input/output signal multiplexers to the proper downlink antennas for retransmission to antennas of Earth satellite receiving stations.
Want to learn more about SATCOM? Tonex offers nearly a dozen courses in Satellite Communications, such as:
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