Q 2.3 How do communication satellites work?

Communication satellites receive signals from ground transmitters, commonly known as Earth stations. Since the received signals are very weak these signals are amplified, processed and retransmitted towards desired regions of the Earth.

Conventional satellites (the majority) simply amplify the weak signals before transmissions. Satellites using advanced technology can modify the received signals to adapt them better for retransmissions. For example satellites may receive transmissions in time divided bursts and retransmit them in a continuous stream, combining individual bursts.

In broad terms satellites comprise a platform or ‘bus’ and a payload. The bus assists in maintaining satellite’s attitude and orbit, accepts ground originated commands, assists ground station tracking by transmitting a beacon, provides DC power, maintains thermal equilibrium and provides desired structural support, The payload performs the task related to communication. It comprises a repeater, which processes the received signals and readies them for transmission, and antennas, which collect and distribute the radio frequency signals in the service area.