Shulou(Shulou.com)11/24 Report--

The launch of Huawei's Mate60 Pro sparked a buying spree, and three years later, Huawei's mate series finally released new phones. The most eye-catching thing about Mate60Pro is that besides the unicorn 9000s, which is not yet known, there is also a very important function-satellite calls, so that your calls can be connected to Jiuxiao anytime, anywhere, across mountains and seas.

What is the technology of hoisting and blowing up the sky? Can you really pierce the sky? Today, the Radio Frequency School will explore with you how this technology of "poking up the sky" is in the end.

What is a satellite? Now, the concept of man-made satellite must be not too strange, what star chain, GPS, Beidou, quantum satellite, every word about man-made satellite will arouse heated discussion.

Do you know when the first man-made satellite was sent? What can it do?

Astronomers divide the stars in the sky into three categories, stars, planets and moons. Our sun is a huge star. Countless nuclear explosions occur inside the star all the time, and then release energy to the outside world in the form of electromagnetic waves. Like the earth, it cannot release energy to the outside world. The stars that move around the stars are called planets, and the stars that move around the planets are moons, such as our moon. The moon, like a security guard, guards around the planet, fending off most of the critical attacks from the universe.

Man-made satellites are unmanned spacecraft made by human beings that can operate in the orbit of the earth. To date, mankind has launched a total of about 50000 man-made satellites, most of which have lost their function and become space junk.

The picture on the right is what you think, but the middle picture is the actual state. So our heads are actually covered with man-made satellites. At the current launch rate, the number of man-made satellites will increase exponentially, and scientists predict that by 2209, the density of man-made satellites on the earth's surface will be the density shown on the far right.

These artificial satellites, of different sizes and functions, serve all aspects of human beings, including military, meteorological, broadcasting, communications, navigation, reconnaissance, early warning, scientific experiments and so on.

Of course, as one of the most aggressive creatures, military use comes first. The launch of the first man-made satellite was accompanied by a fierce military technological confrontation between the two camps during the Cold War.

The former Soviet Union successfully launched the first man-made satellite in human history on October 4, 1957-Sputnik-1,Sputnik means companionship in Russian, and Sputnik-1 literally translates to Sputnik 1. What a domineering name, it's just number one. Fortunately, we use transliteration and call it Sputnik one directly.

The Sputnik-1 satellite was remade by Korolyov, a rocket expert from the former Soviet Union, with an elliptical orbit at an altitude of 215km / 947km and a tilt angle of 65.1 °. It adopts spin stability control mode. The satellite is spherical with a diameter of 0.58 m and a mass of 83.6kg. It is mainly composed of a shell, satellite equipment and an antenna. The satellite shell is made of two aluminum alloy hemispherical shells butted and sealed, and is filled with nitrogen. Battery packs, radio transmitters and other instruments and equipment are installed in the shell. There are four whip antennas on the outside of the satellite, two 2.4m long and two 2.9m long. The spaceborne radio transmitter transmits radio signals at the frequencies of 20.005MHz and 40.002MHz.

Sputnik-1 worked for a total of 22 days, and on October 26, 1957, the battery ran out and stopped sending signals. It then traveled in space for another three months, and on January 4, 1958, it re-entered the Earth's atmosphere and burned.

This man-made satellite initiated the first step in the development of outer space, from then on, human activities range from land, ocean, atmosphere, to outer space, opened the Southern Heavenly Gate, and moved to heaven. Of course, the successful launch of Sputnik-1 also greatly stimulated the United States and caused panic in the United States. Since then, the Cold War has extended from the surface of the earth to space.

Then, on January 31, 1958, the United States successfully launched the Explorer-1 satellite, a relatively small satellite, only the size of two basketballs, weighing only 8.22kg and a cone-shaped cylinder, 203.2 cm high and 15.2cm in diameter, orbiting the Earth in an elliptical orbit of 360.4 km perigee and 2531 km apogee with an inclination of 33.34 °and a period of 114.8 minutes.

Then, France and Japan also launched their first man-made satellite one after another.

After Japan successfully launched its first man-made satellite, China also launched its first man-made satellite, Dongfanghong-1. The successful launch of Dongfanghong-1 ushered in a new era in China's space history, making China the fifth country in the world to independently develop and launch man-made earth satellites after the Soviet Union, the United States, France, and Japan. In that poor era, scientists, with their strong perseverance and dedication, hand-drawn the drawings of man-made satellites and completed the successful launch of China's first man-made satellite.

The Dongfanghong-1 satellite is composed of structure, temperature control, energy, "Dongfanghong" music device, shortwave telemetry, tracking, antenna and attitude measurement components. The main task is to carry out satellite technical experiments and detect the density of the ionosphere and the atmosphere. The 72-hedron, which is nearly quasi-sphere in shape, is about 1 meter in diameter and 173 kg in mass. It adopts spin attitude stabilization mode and rotational speed is 120 rpm. The attitude is determined by solar goniometer and infrared field leveling instrument. Use the electromagnetic wave of 20MHz to play the song of "the East is Red" to the world.

After Dongfanghong-1 worked for 20 days, the battery ran out and stopped sending electromagnetic signals to the outside world. However, the orbital life of the satellite is not over. Today, Dongfanghong-1 is still operating above our heads, announcing to the world the rise of China's science and technology.

What is a communication satellite? Satellites have a variety of uses, among which communication satellite is one of the earliest and most widely used man-made satellites.

A geostationary satellite can cover about 40% of the earth's surface, including oceans, mountains, land and low altitude. Human beings in the geostationary orbit, the uniform distribution of three communication satellites, can cover global communications.

The geostationary orbit is located high above the equator 35786.6Km. In this orbit, the satellite orbits the earth from west to east at a speed of 3075 meters per second. The time of orbiting the earth is 23 hours, 56 minutes and 4 seconds, which is exactly the same as the time of the earth's rotation. Therefore, seen from the ground, the satellite seems to be hanging in the sky, which makes the work of the ground receiving station much more convenient. The antenna of the receiving station can be fixed at the satellite and communicate day and night without having to "shake" around like tracking those moving satellites, making the communication time intermittent. Communications satellites have undertaken all intercontinental communications services and television transmission.

Geosynchronous satellite covers a wide range, but the utilization of spectrum is relatively low. Because the electromagnetic wave transmission distance is relatively long, so the signal delay is also relatively large, reaching 250ms, far exceeding the transmission delay between the earth surface base stations. However, the coverage of ground mobile base stations is small, usually within 1-5Km, the construction cost of full coverage is high, and many places do not have the conditions to build stations at all. Therefore, satellite communication in low-Earth orbit has become a hot option.

Low-orbit satellite system refers to man-made satellites operating in low-earth orbit, which is generally about 1000 kilometers from the earth's surface, and the space transmission loss of electromagnetic waves is small. The coverage area formed by the satellite moves quickly on the earth's surface, and it takes about two hours to circle the earth. When the cell moves past the mobile user, there is also the problem of "handoff". However, low-orbit satellites usually weigh only a few hundred kilograms and can be launched with low-thrust rockets, or even more than one arrow, so the launch cost is relatively low.

The main advantages of Leo satellite communication are:

1. The orbit altitude of the satellite is low, which makes the transmission delay short. The path loss is small, the constellation composed of multiple satellites can achieve real global coverage, and frequency reuse is more efficient.

2. Cellular communication, multiple access, spot beam, frequency multiplexing and other technologies also provide technical support for low-orbit satellite mobile communication. Therefore, low Earth orbit (LEO) system is considered to be the latest and most promising satellite mobile communication system.

At present, the main Leo communication satellite programs are Iridium system and Global Satellite system (Globalstar), Aries (Arics) system, Leo Satellite (Leo-Set) system, Coscon system, Satellite Communication Network (Teledesic) system and so on.

Everyone in the communications industry should have heard of Motorola's Iridium plan. The first Iridium satellite project proposed by Motorola to serve the communication of all mankind, the space part consists of seven satellite orbits, each with 11 satellites, just like the metallic element iridium, with 77 electrons outside the nucleus. Although it was later confirmed that six satellite orbits could provide the same coverage, the number of planned satellites was reduced to 66.

The earliest human communication constellation system proposed in 1987, with a mass of about 670kg and a power of 1200 watts, adopts a three-axis stable structure, with 3480 channels per satellite and a service life of 5 to 8 years. The most important feature of Iridium satellite system is that global communication is realized through the relay between satellites, which is equivalent to moving the ground cellular mobile phone system to the sky. Compared with the geostationary orbit satellite communication system, it has two major advantages: first, the orbit is low, the transmission speed is fast, the information loss is small, and the communication quality is greatly improved; second, the iridium satellite system does not need a special ground receiving station, and every mobile phone can contact with the satellite, which makes the inaccessible barren land on the earth, the remote areas with backward communications, and the natural disaster sites unimpeded. Therefore, Iridium satellite system has begun a new era of personal satellite communication.

However, this advanced technology was eventually defeated by the mobile honeycomb in the market competition, and the Iridium project finally had to end in bankruptcy. Later, Iridium was planned to be acquired by the U.S. Department of Defense to serve the U. S. government and military.

Finally, it was the alien Musk's StarLink that came out of the sky, which led to the rapid development of the whole Leo satellite communication.

In 2015, Musk announced that he would launch about 12000 communications satellites into orbit, of which 1584 would be deployed in low-Earth orbit 550km above Earth, a chain that would provide high-speed Internet services to humans. And it's the whole world, no dead corner, anytime, anywhere, whatever, as long as you have money.

By July 2023, a total of 4519 Starlink satellites have been successfully launched, of which 4487 are in operation. At present, it can provide transmission rates ranging from 5Mbps to 200Mbps, which can meet the Internet needs of most people.

The following figure shows the radio frequency parameters of Starlink. The millimeter wave band transmission of 27.5GHz-30GHz is used between the ground station and the satellite, and the 10.7GHz to 12.7GHz band transmission is used between the satellite and the user terminal.

Theoretically, the star link system can cover global communications, but limited by the number of satellites and various reasons, most of the services are still limited to North America and Europe. On Starlink's usability map, the rest of the world is marked as "coming soon", and even parts of the United States are waiting for potential customers.

Of course, China's own star chain plan is also progressing steadily, and it is reported that by 2030, the network of 300 satellites will be completed, which will have the immediate business response and service capability of "visiting any location in the world within 10 minutes". This will provide more effective data and capacity support for global emergency rescue, fire monitoring, disaster prevention and mitigation.

So what's going on with Huawei's mate60pro satellite calls? What kind of satellite is used?

This leads to our communication satellite system-Tiantong-1.

The Tiantong-1 satellite system Huawei mate60Pro uses the Tiantong-1 satellite communication system independently developed by China, which is led by the Fifth Aerospace Academy and currently operated by China Telecom.

The Tiantong-1 satellite mobile communication system is composed of a space segment, a ground segment and a user terminal, and the space segment is planned to consist of a number of geosynchronous orbit mobile communication satellites. Among them, Tiantong-01 was launched by long March 3B carrier rocket on August 6, 2016, marking China's official entry into the Man-Earth N-step orbit Mobile Communications Satellite Club. Then, on November 12, 2020, Tiantong-1-02 was successfully launched, and then Tiantong-1-03 was successfully launched on January 20, 2021.

Tiantong No.1 01 satellite works in S band, uplink 1980MHz-2010MHz, downlink 2170MHz-2200MHz. At this stage, it can meet the communication capacity of 1 million users. The main coverage areas are China and its surrounding areas, the Middle East, Africa and other related areas, as well as most of the Pacific Ocean and Indian Ocean. There is no limit to the coverage of the terrain, and seamless coverage can be achieved in the oceans, mountains, Shangyuan, forests, Gobi and deserts. Covering all kinds of mobile users, such as vehicles, aircraft, ships and individuals, Tiantong-1 can provide round-the-clock, all-weather, stable and reliable mobile communication services in various fields such as personal communications, marine transportation, ocean fishing, air rescue, tourism scientific research, etc., and supports voice, short message and data services in case of natural disasters. In addition, the emergency communication capability of Tiantong-1 can play a great role. The main advantage of Tiantong-01 satellite is that the terminal is miniaturized, mobile and easy to carry. The following picture shows the 5 G Tiantong satellite mobile terminal YT8000 launched on China Telecom's official website, with a price of 9800 yuan.

This Tiantong-1 satellite system is also a communication satellite system for Huawei mate 60Pro to make satellite calls. If your mobile phone has this function, you can log on to Tianyi Cloud website and open Tiantong-1 service.

Tiantong satellite service relies on "Tiantong No.1" satellite mobile communication system and network independently developed by China Telecom, using 1740 exclusive number segment to provide customers with satellite mobile voice, short message, data and value-added services. Tiantong satellite service achieves full coverage of the communication network in China's territory and territorial sea, filling in areas that cannot be covered by existing communications. It is widely used in marine fishery, emergency rescue, tourism exploration, Internet of things and other applications.

Tiantong satellite can not only provide phone calls and SMS services, but also provide Internet services. The current transmission rate is about 384kbps, which is not a small gap compared with Starlink. I believe that in the future, it will break the sky.

However, now that we are on the satellite, the charge is quite expensive, 1000 yuan a year, including 750 minutes of phone calls and five domestic text messages. Beyond the package, both dialing and receiving satellite phones are one yuan and one minute.

Reference reading:

1, https://www.tomsguide.com/news/starlink-internet-coverage-speed-cost-satellites-ipo-and-latest-news

2, https://new.qq.com/rain/a/20230714A00K6600

3, http://www.chinatelecom.com.cn/news/02/202109/t20210927_66332.html

4, https://baike.so.com/doc/24713766-25619257.html

5, https://baike.baidu.com/item/%E5%8D%AB%E6%98%9F/21511

6, https://baike.baidu.com/item/%E9%80%9A%E4%BF%A1%E5%8D%AB%E6%98%9F?fromModule=lemma_search-box

This article is from the official account of Wechat: radio Frequency School (ID:RF_Center), author: RF Carpenter

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