Satellite communication system is actually a kind of microwave communication, it uses the satellite as a relay station to forward microwave signals, communication between multiple ground stations, the main purpose of satellite communication is to achieve "seamless" coverage of the ground, because the satellite works in hundreds, thousands, or even tens of thousands of kilometers of orbit, so the coverage is much larger than the general mobile communication system.

The satellite communication system consists of three parts: satellite end, ground end and client end. The satellite end plays the role of a relay station in the air, that is, it amplifies the electromagnetic wave sent from the ground station and then sends it back to another ground station. The satellite star includes two sub-systems: the satellite-borne equipment and the satellite parent. The ground station is the interface between the satellite system and the ground public network, and the ground user can also form a link through the ground station to enter and exit the satellite system, and the ground station also includes the ground satellite control center, and its tracking, telemetry and command stations. The client is a variety of user terminals.

Satellite communication refers to the communication between radio communication stations on the earth (including ground, water and lower atmosphere) and with satellites as relay stations. It has the advantages of large communication capacity, long distance, wide coverage area, flexible networking, stable and reliable performance, etc. Satellite communication has been increasingly widely used.

The main components of satellite communication system include communication satellite, earth station, monitoring management system, satellite measurement and control system. Satellite communication systems receive and transmit signals from earth stations to space satellites. A typical television satellite takes a signal from a base station and broadcasts it to a large number of receiving stations. The signals sent to the satellite are called "uplink" and the signals received from the satellite are called "downlink". The uplink is also called "bird shooting". The downlink covers an area of coverage called a footprint, which may be very large or cover a concentrated area. Satellites use microwave antennas. Because they are high in the air, transmission reaches the receiver via a line-of-site.

The satellite communication system mainly includes modulation mode and multiple access mode. Modulation methods include FM, PSK (shift key modulation) and other modulation methods. The multi-access technology is used to solve the problem of sharing communication resources without interference when users enter the network. In the general satellite communication, FDMA, TDMA, CDMA and other multi-access technologies are used.