The main application of satellite communication in the current society

Satellite communication can be divided into two categories: geostationary satellite communication and mobile satellite communication, according to different categories, its main applications are as follows:

1. Geostationary satellites refer to geosynchronous orbits.

The satellite, which is characterized by being far away from the earth, has a high power to transmit signals, which limits the transmission equipment to be huge and expensive, and can only be used for industrial applications. At present, it is mainly used in the following aspects:

Satellite television. Due to the characteristics of the broadcast channel, only one transmitting station is needed to make it available to users in different locations, which is the fastest and most low-cost application of satellite TV.

Emergency telecommunications. With the growing demand for domestic emergency requirements, emergency satellite communication has gradually shown great application effects. Especially in the remote and strong geological disaster environment, in the case of losing ground support, an independent satellite communication station can complete the transmission including voice, **, **, and can ensure broadcast-level on-site images.

This is unmatched by any other means of communication.

Applications in harsh environments. It mainly refers to the application in the absence of ground communication facilities in border defense, Gobi, desert, island, etc. Because in such areas, ground optical cables, microwave relay and other means of communication are not available, and the bandwidth required by such applications is not very large, only need to provide voice, ordinary image transmission, which is why VSAT technology can develop rapidly.

In addition, it is the transmission of samples of the first industry and newspapers.

2. Mobile communication satellites refer to low-orbit satellites, that is, near-low-orbit satellites. Due to the close distance from the ground, this kind of satellite requires low transmission signal power, and can be made into a handheld terminal. However, the communication bandwidth provided by this type is also insufficient, and it can only carry out low-speed data transmission.

The most commonly used communications are the Iridium satellite system and maritime satellite communication system in the United States.

In my personal opinion, GPS and meteorological satellites cannot be called "satellite communication" from the user's side, because communication refers to the process of transmitting information to the receiver, which is a two-party behavior. and GPS navigation, positioning and satellite cloud imagery.

The generation and transmission of data is provided by the satellites themselves, so there is no communication. Of course, everyone's point of view is allowed to vary.

Radio and television, fire prevention and disaster relief, weather forecasting, etc.

Satellite communications are used in television, fax, telegraph, and data.

The application field of satellite communication continues to expand, in addition to the financial, post, telecommunications, meteorological, and other departments, distance education, telemedicine, emergency disaster response, emergency communications, emergency television imitation vertical broadcasting, sea, land and air navigation, Internet network, television, etc. will be widely used.

The development of new satellite communication technologies is endless. For example, very small aperture antenna earth station (VSAT) systems, mobile satellite communication systems in medium and low orbits have received extensive attention and applications. Satellite communications are also an important part of the global information superhighway in the future.

It is known for its wide coverage and large communication capacity.

Land-shore broadband coverage is not available, such as satellite broadband in remote mountainous areas and deserts, and offshore satellite broadband at sea.

Some of the advantages and disadvantages inherent in the advantages and technologies that satellite communications can bring are due to the unique nature of satellites being located in space. When the orbit of the satellite around the earth is above the equator and reaches about 36,000 km above the ground, the angular velocity of the satellite around the earth can be controlled to coincide with the angular velocity of the earth's rotation, so that the satellite looks like it is stationary in space when viewed from the ground. At this time, the satellite is called a geosynchronous orbit satellite or a fixed-point satellite, and the satellite communication problems we discuss here refer to the use of such fixed-point satellites.

Satellite communication is the realization of our proverb - "stand high, see far", standing at a high altitude of 36,000km, the coverage of satellite signals can reach one-third of the earth's area. A satellite relay can be used to connect any two points within the satellite coverage area (Figure 3-1, Figure 3-2). It can be seen that the characteristics, advantages and disadvantages of satellite communication are as follows.

Figure 3-1 Communication between two points on the ground is carried out by satellite.

Figure 3-21) Some unique features of satellite communications: Generally not affected by natural disasters on the ground; security of destination and source sites; The construction cost is not related to the communication distance; The operating cost is not related to the communication distance; The construction is particularly convenient and fast; The technology is mature and the equipment is reliable.

2) Advantages of satellite communication: long transmission distance; The coverage area is large and the surface multi-point communication can be realized in the coverage area; Good maneuverability and flexibility.

3) the most suitable applications for satellite communications; Places that are difficult to reach by other means of communication (mainly ground line communication) (such as deep mountains, islands, etc.): Places where temporary communication stations need to be quickly established (mobile stations, vehicles, ships, airbornes, etc.); The need to provide a backup link for wired communications.

4) Some disadvantages of satellite communication: limited available resources and high operating costs; It will be affected by the natural environment (such as solar transit, rain and fog weather, etc.); The signal delay caused by the transmission of satellite signals in space.