Telecommunication

Telecommunication components for a space shuttle are chosen in response to the requirements of the mission it will perform. Anticipated distances, planned frequency bands, data rates and available on-board transmitter power are all taken into account.

High-gain antenna: A dish-shaped antenna used for high rate communication with Earth. This type of antenna is highly directionally and must be pointed to within a fraction of a degree of Earth. It may be either steerable or fixed to the shuttle. High-gain antennas are typically used on interplanetary missions.

Low-gain antenna: An omni directional spacecraft antenna that provides relatively low data rates at close range, for example several astronomical units. Many spacecraft include both a low-gain antenna and a high-gain antenna.

Medium-gain antenna: A spacecraft antenna that provides greater data rates than a low-gain antenna, with wider angles of coverage than a high gain antenna, about 20-30 degrees.

Transmitter: An electronic device that generates and amplifies a tone. The transmitter sends the signal from the antenna. This process is known as downlink.

Receiver: An electronic device that receives incoming radio signals, called uplink, and converts them to perceptible forms.

Frequently, transmitters and receivers are combined into one electronic device, which is called a transponder.