Table of Contents

Satellite Communications

Design of a Telecommunication Satellite

Teacher Background

This background section assumes that teacher knowledge of satellite communications systems is limited to an identification of major systems (ground station, satellite, receivers, transmitters, connection to telecommunications network). This resource focuses mainly on the technology aspects of telecommunications as opposed to the science aspects. A definition of some of the terms used here can be found in the resource Space Age Telecommunications in Canada.

Students at this grade level also have very limited prior knowledge with regard to what components are needed to make systems such as this function. Here is a list and a description of the important components of a telecommunication satellite system.

Major components:

• A source of information (TV signal, INTERNET, Telephone, computer)
• Ground station to transmit information to the satellite (Uplink Ground Station),
• The satellite
• Receiver ground station to receive the signal.
• End user (television, telephone computer)

Components of a communication satellite

A communications satellite needs a number of components and systems so that it may function in geostationary orbit.

Physical Structure:

• This system is the box or cylinder needed to house all the other components and to attach other systems to.

Power system:

• Needed to power the satellite. This will include solar panels, batteries and a power supply that can take the energy produced by the panels and batteries and turn it into energy needed to run the spacecraft systems and power the satellite downlink.

Control system:

• This system is needed to maintain the orientation of the spacecraft so that the transmitting antenna covers the footprint for the satellite. An example of this system is one that includes thrusters that allow the satellite to rotate when in its assigned orbital position, or to allow the satellite to change orbital position. This system usually includes a sensor that can identify when the satellite is looking at Earth.

Receiver system:

• This system is needed to receive the signals directed to it from ground stations. It included an antenna (e.g. a dish) and a receiver. The receiver converts electromagnetic radiation into electrical signals that are manipulated by the spacecraft.

Transmitter system:

• This system takes the signals that are to be transmitted to the ground, amplifies them and broadcasts them to Earth. It includes a transmitter, a device that converts electrical signals into electromagnetic waves and an antenna, which distributes the broadcasted signals back to Earth.

Propulsion:

• Rocket engine and fuel, and electronics to control it for moving the satellite into geostationary orbit and to move the satellite out of orbit at the end of its lifetime.

Command and Control System:

• This system is used by people on the ground to monitor and control the spacecraft and to understand any problems that may be occurring on the satellite.

Components of a Ground Station:

• Source of signal usually a land line connected to a TV network, the Internet or potentially to another satellite system
  
  
• An antenna that includes a transmitter for the information and a steerable reflector to direct the signal to the satellite. For a receiving station, a receiver and a collecting reflector.
  
  
• A building to house the components
  
  
• A power source - such as an electrical grid.