What are the advantages of communication satellites?

Communication satellites have the advantages of long communication distance, large capacity, good signal quality, high reliability and strong flexibility, so they are widely used in long-distance communication, data network, TV education, data collection, e-mail, government administration, emergency rescue, telemedicine, maritime communication, personal mobile phone and other fields.

A geostationary satellite fixed above the equator can cover more than 40% of the earth's surface, and several synchronous communication satellites and ground stations can form a global satellite communication system. At present, there are about 300 synchronous communication satellites in the world, which provide 80% international communication services to more than 200 countries and regions, forming the largest aerospace industry with tens of billions of dollars every year. For example, the satellites of the International Telecommunications Satellite Organization have developed to the eighth generation, and there are 17 satellites in orbit. Intelsat-8 carries 44 transponders, has controllable C-band spot beam, and can provide 3 TV channels and 1 12500 digital voice channels.

In recent years, there have been constellations of mobile communication satellites in near-earth orbit. For example, the iridium satellite system is a constellation consisting of 66 satellites. The technology is very advanced, but the telephone bill is too expensive ($3/min). As a result, the iridium company went bankrupt. But this trend is still developing.