At 01:56 on March 30, 2018, Xichang Satellite Launch Center, the Long March 3B carrier rocket successfully launched the 30th and 31st Beidou navigation satellites in the "one arrow and two stars" way, which is also the seventh and eighth networking satellites of our country’s Beidou-3.
Recently, Yang Changfeng, the chief designer of the Beidou satellite navigation system, revealed in an interview with the upstream news · Chongqing Morning Post reporter that 18 Beidou satellites will be launched this year, and services will be provided to countries along the "Belt and Road Initiative" by the end of the year; by 2020, a world-class Beidou system will be built; in 2035, a Beidou system will be built with the Beidou system as the core, and a national Beidou integrated positioning and navigation timing (PNT) system that seamlessly covers multiple means of integration, high precision, safety and reliability, and all things are interconnected and intelligent. By then, space-time information services will penetrate into every corner of our lives, and Beidou will be everywhere and always present.
technical blockade
An atomic clock with a 3 million-year error of one second
In the Gulf War, the precision strike performance of GPS-equipped weapons shocked the world, and our country made a major decision in 1994 to develop its own satellite navigation system, named "Beidou".
However, the development process was not smooth.
In 2005, there was a problem with the atomic clock of the Beidou-2 under construction. The high-precision time reference technology is the core technology of the satellite navigation system, which directly determines the navigation and positioning accuracy of the system and plays a decisive role in the success or failure of the entire project.
"In the early days of development, the technology was limited at that time, so we wanted to import it from abroad, but we didn’t expect foreign countries to block our technology, which became the biggest bottleneck in the construction of the Beidou satellite navigation system at that time." Yang Changfeng said that because of this, Beidou people have strengthened their belief in self-reliance.
"After this incident, we came to a consensus that the core and key technologies must be broken through by ourselves and cannot be controlled by others. At that time, our Beidou people said something like this, there were atomic bombs in the 1960s and 1970s, and we Beidou people must have our own atomic clock."
After that, the Beidou people set a goal for themselves to develop an atomic clock with an error of only 10 to the power of -12. In layman’s terms, this atomic clock would only have an error of one second every 100,000 years.
To this end, Beidou established three teams to carry out research and development at the same time, and to advance simultaneously in the fields of basic theory, materials, engineering, etc. In this way, in just two years, Beidou overcame the biggest technical obstacle, the atomic clock.
Not only that, the atomic clock now used on the Beidou-3 has been improved to an accuracy of 1 second error every 3 million years, which fully meets the positioning accuracy requirements of our country and the service life of the satellite.
Speaking of this, Yang Changfeng was extremely proud, "This kind of ability is forced out. To this extent, we scientific and technological personnel rely on this kind of ability. Whether it is called backbone or hard work, we finally took it down."
Yang Changfeng said that the current Beidou satellite positioning system’s high-precision location-based service system has reached the dynamic sub-meter level, centimeter level, and post-processing millimeter level.
Key three days
Holding the transponder like holding your own child
After breaking through the technical difficulties of the atomic clock, the Beidou people faced another challenge.
When our country began to develop the Beidou satellite navigation system, the United States and Russia had occupied the most suitable frequency band for satellite navigation, and Beidou had no frequency available. The premise of navigation satellites is to have legal orbital positions and frequency resources, which are precious resources that countries must compete for.
"With the help of China and the European Union, the ITU has maximally squeezed out a small segment of the air navigation frequency band for the common use of satellite navigation in various countries. This small segment only accounts for a quarter of the golden frequency, but it is the basic requirement for building a global satellite navigation, and all countries can apply."
On April 18, 2000, China’s Beidou and the European Union’s Galileo system were successfully applied for simultaneously.
According to the rules of the ITU, the orbital position and frequency resources are not permanent, and the valid period is only 7 years. The country that successfully applies must successfully launch the navigation satellite within the valid period to be considered to have successfully occupied this space "land".
This track and frequency resource was snatched by Yang Changfeng leading the Beidou in the last battle.
"That is to say, on April 18, 2007, we did not receive the signal and automatically withdrew from the position of’space land ‘." According to the original deployment, our country would not launch the first Beidou navigation satellite until the end of 2007. "If we follow the original plan, the orbital position and frequency resources we finally applied for will expire."
In order to maintain this orbital position and frequency, the Beidou people worked around the clock, and the satellite entered the final launch phase in early April 2007.
"At that time, the satellites were all on the launch tower, and suddenly there was an abnormality in the transponder."
Yang Changfeng explained that the transponder is used to connect the sky and the ground. "With this transponder, we will know whether the signal in the sky is connected to the signal in the ground."
"At that time, the signal of the transponder was unstable, sometimes good and sometimes bad. In order to ensure access to frequency resources, this signal was necessary." Yang Changfeng said that this signal was very critical. "There were only three days left for us at that time. In order to be foolproof, we decided to repair the transponder."
So they climbed the tower, switched on the rocket, peeled off the satellite, took out the faulty transponder, and immediately rushed from Xichang to Chengdu, starting from scratch, to re-test the transponder. During the transportation of the transponder from Xichang to Chengdu, the Beidou people held the transponder tightly like their own children.
During his three days in Chengdu, Yang Changfeng confessed, "To be honest, my mood is tense, heavy, and the pressure is also very high. I basically didn’t sleep for 72 hours."
After the transponder was repaired, it was sent back to Xichang. At 4:11 on April 14, the first satellite of Beidou-2 was launched from Xichang.
At 20:00 on April 17, the first set of satellite signals was sent, "At that time, we were in the playground and set up a table with more than a dozen receivers. When we received the signal at the same time, everyone in the playground cheered and jumped. I was so happy that I cried, really unconsciously."
Yang Changfeng said that he didn’t think much about it at that time, "I just think we finally got this signal, and the road to our Beidou development has been opened."
At this point, there are less than 4 hours left until the limited time.
Beidou is not far
Opened a life passage for the rescue of Wenchuan disaster area
Beidou seems far away from us, but it is actually very close.
During the 2008 Wenchuan earthquake, when communications, electricity, and transportation were all destroyed, and the disaster area lost all contact with the outside world, Beidou used its unique short message function to report the situation in the disaster area in real time to the command center in text, opening a life channel for rescue.
There are also shared bicycles that everyone is familiar with. Beidou’s precise positioning can help shared bicycles park. "If it exceeds a certain distance beyond the parking range, it will automatically prompt." Yang Changfeng said.
The transportation department has used Beidou to form a vehicle supervision system to monitor and monitor some dangerous goods transporters, long-distance buses, and tourist buses in real time. Compared with the original period, the accident rate and casualty rate have dropped by 50%.
The Beidou satellite navigation system, whose positioning is accurate to the sub-meter and centimeter level, is installed on the mobile phone to solve the confusion of finding the way for "road idiots"; it can detect the shaking of buildings in strong winds, and can help monitor some natural disasters; the herdsmen on the grassland use Beidou to supervise the flock and graze… As Yang Changfeng said, "Beidou is omnipotent and omnipresent. I’m afraid you didn’t expect it, and you can’t do it, so you dare to think about it, and it will be useful if you think about it."
quotation
○ "There were atomic bombs in the 1960s and 1970s, and we Beidou people must have our own atomic clock."
○ "This kind of ability is forced out. To this extent, we scientific and technological personnel rely on this kind of ability. Whether it is called backbone or hard work, we finally took it down."
○ "At that time, we set up a table in the playground, and there were more than a dozen receivers. When we received the signal at the same time, all the people in the playground cheered and jumped. I was so happy that tears welled up in my eyes."
○ "Big Dipper is omnipotent and omnipresent. I’m afraid you didn’t expect it and couldn’t do it, so I thought boldly, and it will be useful if you think of it."
dialogue
With Beidou navigation, will you get lost in Chongqing?
Chongqing Morning News:It is said that Chongqing is a 5D magic city, and navigation must be lost. Will Beidou navigation get lost in Chongqing?
Yang Changfeng:When I recorded the "Let’s Talk" program on CCTV last year, I saw the magic of Chongqing. At that time, an audience member said that she was a road idiot and could not tell the direction at all, so she talked about the Xizhimen overpass in Beijing, "the first of the labyrinth". Later, Xiao Sa directly took out the Huangjuewan overpass in Chongqing. I heard that there are 5 floors above the ground, with a total of 15 ramps.
Now our Beidou satellite navigation system has achieved high-precision navigation, which can be accurate to decimeters, centimeters, roadbed navigation, and lane-level navigation. As long as the map is updated in a timely manner, the Beidou satellite navigation system can allow you to better experience the "magic" of Chongqing.
Chongqing Morning News:Which floor are we on, can Beidou also locate it accurately?
Yang Changfeng:In 2035, when we form the National Beidou Comprehensive PNT (Positioning Navigation Timing) system, we will be able to achieve seamless connectivity between indoor, outdoor, sky, ground, and sea. Of course, you will be able to locate your location on which floor you are on.
Chongqing Morning News:I heard that there are a lot of young people in Beidou Engineering Construction?
Yang Changfeng:The majority of our Beidou construction team are doctoral students, basically around 30 years old. Now the post-90s generation is also slowly growing up, especially our Beidou No. 3 project, which relies on these young people to support it. The new generation of Chinese youth will continue to play an important role in the construction of the Beidou system after a period of tempering.
In order to encourage more young people to learn about Beidou and China’s aerospace industry from an early age, we also held a youth activity competition on Beidou and held lectures on popular science knowledge.
Beidou Calendar
The three stages of the Beidou project
Since October 2000, the Beidou program has successfully launched more than 30 Beidou satellites in three phases.
From October to December 2000, the Beidou-1 system was successfully completed and four satellites were launched.
From 2007 to the end of 2012, the Beidou-2 system was completed to provide services to the Asia-Pacific region. "Beidou-2" is not a simple extension of "Beidou-1". It solves the technical problems of the "Beidou-1" system and provides a full range of global navigation and positioning services by sea, land and air.
From 2017 to around 2020, the Beidou global system will be completed to provide services globally.
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