Low-altitude economy theme: satellite communications
As we all know.
Our daily life has been closely connected to the Internet
All kinds of network devices are connected to each other
Together, they build a convenient and efficient network for our lives.
So much so that we seldom wonder
Are communication networks really everywhere?
Oceans, deserts, jungles, ice fields, etc., are places not covered by mobile communication networks. On the one hand, there are engineering and technical difficulties in the construction and maintenance of base stations, and on the other hand, the construction capital is expensive and the utilization rate and return are too low.
How should the communication needs of these forgotten fringe areas be met? How to build a communication network with global coverage that is not limited by the terrestrial environment? Is there such a program? Perhaps “satellite communications” will give us an answer.
01.Meaning of satellite communications
Satellite communications are communications between radio communication stations on Earth (both on the ground and in the lower atmosphere) using satellites as relays. Compared with traditional cellular network communications, the wireless signals of satellite communications are relayed by satellites, and a single node can cover a larger service area. After completing the laying of the satellite network, communication satellites can complete the process of signal forwarding within the orbit, relaying the information between cellular phones and satellite base stations in a relay manner.
For reasons of time delay, interference and cost, modern civil satellite communications are mainly based on low-orbit satellites.
Compared with communication satellites in other orbits, low-orbit communication satellites have short transmission delays and small path losses, and constellations composed of multiple satellites can realize truly global coverage and more effective frequency reuse; together with point-beam, multiple-access and other technologies, they also provide technical guarantees for mobile communications by low-orbit satellites. Therefore, low-orbit communication satellites are considered to be one of the satellite mobile communication technologies with the most promising applications.
02.Principles of satellite communications
The satellite communication system consists of three parts: the satellite side, the ground side and the user side.
1.Satellite terminal
In the air to play the role of relay station, that is, the ground station sends up the electromagnetic wave amplification and then sent back to another ground station.
2.Ground terminal
It is the interface between the satellite system and the terrestrial public network, and terrestrial users can also form links to and from the satellite system through ground stations.
3.User terminal
That is, they are various user terminals such as computers, cell phones, modems, etc. They communicate with satellite communication systems through ground stations to exchange information at different locations on Earth.
Together, the above three components form a satellite communication system that realizes the purpose of communication via satellite between multiple earth stations.
As users, how do we access the satellite network, other than using a cell phone that can connect to the satellite?
Nowadays, it is mostly through the introduction of a terrestrial receiving device, like the old TV “pot”, to receive communications from the satellite band. After the signals from the satellite are received by the “pot”, they are converted into WiFi signals through a wireless router, and the cell phone can access the Internet through the WiFi signals!
03.Applications and development trends of satellite communications
Satellite communication has the advantages of wide coverage, long transmission distance and strong anti-interference ability, and is widely used in various fields:
Broadcasting and television: Satellite communication is the main means of realizing the dissemination of global broadcasting and television programs, such as CCTV's Spring Festival Gala and the live broadcast of the Olympic Games.
Mobile communications: Satellite communications enable mobile communications on a global scale, such as maritime communications and aeronautical communications.
Military communications: Satellite communications play an important role in the military field and can realize functions such as remote command and battlefield intelligence collection.
Internet access: Satellite communications can provide Internet access to remote areas and narrow the digital divide.
Disaster rescue: In emergencies such as natural disasters, satellite communications can quickly restore communication facilities and provide strong support for rescue work.
In April 2020, the National Development and Reform Commission (NDRC) for the first time included satellite Internet as a network infrastructure in the scope of “new infrastructure”. 2021, the Ministry of Industry and Information Technology (MIIT) pointed out in the “14th Five-Year Plan” for the development of the information and communications industry that there are shortcomings and weaknesses in China's information and communications industry, such as the imperfect global layout of international submarine cables and satellite communications networks. The Ministry of Industry and Information Technology pointed out in the “14th Five-Year Plan” that there are shortcomings and weaknesses in China's information and communications industry, such as the imperfect globalization layout of international submarine cables and satellite communications networks. According to the plan, by 2025, China's satellite communication network will provide global information network services for all kinds of users on land, at sea, in the air and in the sky.
It is expected that by 2030, broadband satellite communication will form a comprehensive link of high speed and high user density with the sea, land and air, and extend to the Earth-Moon space to support the business link of the whole scenario, realize the real-time response and processing of space information, and form a satellite communication information highway.
By then, human cyberspace will leap to a new dimension!
High quality
