Satellite communication

Satellite communication became a possibility when it was realized that a satellite orbiting at 36000 km from the earth would be geostationary. Such a satellite has a period of revolution of 24 hrs while revolving round the earth. Thus it would appear to remain stationary relative to the earth if placed in an equatorial orbit. A source or terminal on the earth transmits a radio signal to the satellite. Satellite receives it, processes it and transmits to the earth. On the earth, there is another terminal which receives the signal. Advantages are
High availability and reliability
Wide coverage area
Advanced communication alternatives
Security communication through satellites