What is the progress of the low orbit communications satellite constellation in 2017

Low Earth Orbit (LEO) Satellite System: 1. Low Earth Orbit Satellite Concept Description: Orbital communication satellites operate in space at different altitudes from the earth's surface, but lower than the orbit of geosynchronous satellites At this time, because the time for satellites to rotate around the earth is faster than the rotation of the earth itself, and the ground station can only communicate with satellites in a short range

It should be that China already has a Beidou satellite.

Global coverage.

Judging by the planning of the project,Amazon will launch 3,236 low-Earth orbit satellites to provide low-latency, high-speed broadband internet services to people living between 56 degrees north and 56 degrees south latitude (95% of the world's population).

Before figuring out what the "Internet of Space" is, it is necessary to review how the LEO satellite constellation has gradually turned from a commercial rookie to a "sewer" project.

In fact, as early as the 80s of the last century, communication satellite technology began to be applied in the field of personal communication.

At this time, some entrepreneurs saw the huge commercial value hidden in it and participated in the construction of satellite companies. Examples include Bill Gates' teledesic, Motorola's Iridium program, and so on.

The contradiction between high R&D operating costs and ordinary consumers. Regardless of the high cost of system development and satellite launch, the voice communication services provided by satellite operators are extremely expensive, and even now they are only valuable in special environments such as ocean cruises, which is difficult to attract more paying users and cannot benefit the population in areas without network coverage.

Because low-orbit satellites are a new field with many advantages, they will become new hot spots.

Because low-orbit satellites are related to the global communications industry, low-orbit satellites are generally used to transmit signals.

Because this is very advanced for technology, low-orbit satellites can monitor faster.

Because low-orbit location is the trend of the future, it has become a new hot spot in the field of science and technology.

Because this may be more useful to humans, people will pay more attention to this.

Because people nowadays are looking for something better, that's why it's like this.

In the future, Starlink networking will provide Internet access services for areas with poor Internet services around the world, and provide "advantageous" broadband services for urban areas.

This is mainly because it is a new hot spot in the field of technology.

Mainly because it's a new technology, it's a new field of research.

Because it's a truly global pass

Apple 13 will support low-orbit satellite communications --

The advantages of using low-orbit satellites to realize handheld personal communication are: on the one hand, the orbital altitude of the satellite is low, which makes the transmission delay short. The path loss is small, and the constellation composed of multiple satellites can achieve true global coverage, and the frequency reuse is more effective. On the other hand, technologies such as cellular communication, multiple access, point beam, and frequency multiplexing also provide technical support for low-orbit mobile satellite communication.

Thus, the LEO system is considered the latest and most promising satellite mobile communication system.

Mobile communication satellites are a new variety of communication satellites. In order to receive and transmit radio signals, large antennas with a diameter of tens of meters or more than ten meters must be built on the ground, so before the 90s of the 20th century, the vast majority of communication satellites were communication services for fixed users on the ground. If mobile users want to use communication satellites, only larger users such as ocean-going ships can install large-diameter antennas.

Therefore, the early mobile communication satellites were called "maritime satellites", which were specially designed for communication between ships sailing on the sea and the shore.

With the increase of the transmission power of communication satellites and the improvement of the sensitivity of receivers, the ground communication antennas have gradually shrunk, and the users of mobile satellite communications have expanded to mobile bodies such as airplanes, trains, automobiles, and fishing boats. As for the mobile communication machine for personal use, the "Big Brother" cannot directly communicate with the mobile communication satellite in geostationary orbit. Its transoceanic and transnational communications are actually received through the "setter"** of the ground station.

Since the 90s of the 20th century, mobile communication satellites in medium, high and low orbits have begun to develop due to the shortcomings of geostationary orbit satellites, such as being far from the ground, serious radio signal attenuation, obvious signal lag, and poor communication effect in high latitudes. A low-orbit mobile communications satellite system called "Iridium" has been built and will soon be put into commercial use. It consists of a constellation of 66 satellites, distributed over 6 orbital planes covering the globe.

Since the orbital altitude of the "Iridium" satellite is only 760 kilometers and it is close to the ground, it can directly communicate with the satellite with a personal handset, and communicate with any place in the world through the link between the satellites and satellites of the "Iridium" system, so as to realize global personal mobile satellite communications.

In addition to the Iridium system, a non-geostationary orbit mobile communications satellite system called "Global Star" and another called "medium circular orbit" are also being developed, which will compete in the individual global mobile communications satellite market.

China's first geostationary communications satellite was launched on April 8, 1984.

At 21:35 on April 24, 1970 (Beijing time), the Dongfanghong-1 satellite was launched by the Long March-1 carrier rocket, starting China's long march into space. More than 10 minutes later, the Dongfanghong-1 satellite successfully entered an orbit around the earth with an inclination angle, a perigee altitude of 439 kilometers, and an apogee altitude of 2,384 kilometers.

Uses of low-orbit satellites: military target detection, mobile phone communication.

In order of the number of moons, Saturn has 18, Uranus has 17, Jupiter has 16, Neptune has 8, Mars has 2 and Earth has 1 each. The volume and mass of different satellites vary greatly, and there are seven satellites with a radius greater than 1000km, and the Moon is one of them.