Block Diagram of Satellite Communication System

Block Diagram of Satellite Communication System Points : block diagram of satellite communication system A simplified block diagram of a communication system using single transponder is shown.

The uplink frequencies (5.9 to 6.4 GHz) are used for transmission from the earth station to the satellite and downlink frequencies (3.7 to 4.2 GHz) are used for transmission from the satellite to the earth station. The uplink signals are converted to lower frequencies by the mixer and local oscillator. The communication satellite acts as a repeater, it receives the signal, amplifies it, then changes the frequency to avoid interference between the uplink and downlink, and the signal is transmitted back to the earth where 11 is received by one or more earth stations. The two-way communication is established with the help of transponders. A communication satellite has multiple transponders. The number of transponders per satellite has increased over the years. For example, a satellite with two transponders can support either a single television channel or 240 telephone circuits. A satellite with 12 transponders can accommodates 4000 telephone circuits and two television channels. A satellite equipped with 8 transponders can accommodate 24000 simultaneous two-way telephone circuits and three television channels. Using digital technology, a satellite can handle 120,000 simultaneous two way telephone circuits.