"I don't understand. It is clearly stated in the history books that Beidou navigation uses two stars for positioning. Why do you need four when you are here?"
No matter whether it makes sense or not, it is Fang Yuan's ability to always find a point to fight back.
"The dual-star positioning refers to [Beidou-1]. Of course, this is a relatively popular term. The scientific name is [Beidou Satellite Navigation Test System]."
"After all, aren't two pills enough?"
If the general direction is not correct, just cut off the part facing the general direction.
Enduring to the end is victory.
"The dual-star positioning system actually has three stars, two working satellites and one backup satellite."
Fang Yuan finally couldn't find any excuses and began to listen obediently as Liang Tian told the story.
The accuracy of the dual-star positioning system is within one hundred meters. If calibrated, the accuracy can reach twenty meters.
This kind of accuracy is definitely not as good as the later [Beidou-2] and [Beidou-3].
But that is under specific historical conditions. Double-star positioning is the fastest way for a country to have an independent satellite navigation system.
In the eyes of astronauts, the first step of the three-step process, starting from scratch, is the most important.
Without [Beidou-1], there is no way to legally own your own satellite navigation system.
But [Beidou-1] is experimental in nature. The three satellites were launched on October 31, 2000, December 21, and May 25, 2003 respectively.
The scope of use is limited to our country. After the satellite life expires, the service will be stopped.
At this point, you still cannot legally own a global satellite navigation system.
According to ITU regulations, two conditions need to be met to legally use a frequency band.
First, apply to ITU.
ITU will inform the applicant when it will accept the application.
The applicant needs to start using this frequency band within 7 years based on this notification time.
If failed to be used successfully, the application will be deemed invalid.
The frequency band application time for China's Beidou navigation system was April 18, 2000.
The frequency band application time for the European Galileo navigation system was June 5, 2000.
Applications are made at similar times.
Because good frequency bands have been occupied as early as the 1980s.
The frequency bands applied for by Beidou and Galileo are highly overlapping.
The second condition of the ITU becomes particularly important at this time - when multiple parties apply for the same frequency, they can coordinate with each other, and they can share it as long as the user feels that there is no interference.
If coordinated, all parties can use it legally.
At the beginning, Beidou people’s idea was, [Hello, hello, hello, hello, hello to everyone].
There are only so many frequency bands left, so work hard to cooperate and find ways not to interfere with each other.
In 2003, after the last test satellite of Beidou-1 was launched, China invested 230 million euros and signed an agreement with the European Union to participate in the Galileo project.
In the following two years, Beidou people gave everything and gained almost nothing.
The first is the core accessory rubidium atomic clock.
According to the original idea of Beidou people, each Beidou satellite will carry four rubidium atomic clocks.
One is made in China and three are imported.
At that time, our country did not have the ability to manufacture rubidium atomic clocks with an accuracy that could meet the standards of navigation satellites (with an error of less than one second in a million years).
From the beginning he agreed to sell to us, but then he disagreed.
After much negotiation, we finally found a company that was willing to sell it, but the delivery time and accuracy were greatly compromised.
I don’t know if it’s really a technical reason, or it’s a deliberate attempt to prevent us from legally owning the frequency band.
Time came to 2005, and Beidou people reluctantly withdrew from Galileo.
[Hello, hello, hello, everyone] This road no longer works.
Only by creating China's own rubidium atomic clock can we have China's own navigation.
This process has seriously slowed down our country's legal acquisition of ITU frequency resources and orbital locations.
Galileo launched its first test satellite, Galileo-a, on December 28, 2005. Half a month later, on January 12, 2006, Galileo launched a navigation signal.
At this time, Beidou people were still working hard day and night on the rubidium atomic clock.
"Old man Liang, what you said here is that the navigation signal was launched on January 12, 2006. Does that mean it was officially used?"
Liang Tian nodded: "That's right."
"Ah? Doesn't Galileo legally have the priority to use the frequency band?"
"The Europeans think so. According to this progress, China will not be able to build its own rubidium atomic clock before the end of the frequency band use in 2007."
"I'm referring to the first-use, first-served policy you mentioned before. According to this logic, Beidou will have no chance in early 2006."
"Yes, things have developed to this point, and the Galileo people who have the chance to win are more or less too lazy to take care of it, but don't forget what the second provision of the ITU is written."
Fang Yuan recalled what Liang Tian had just said: "[When multiple parties apply for the same frequency, they can coordinate with each other. As long as the users feel that there is no interference, they can share it.]"
After recalling it, I still felt there was a problem: "In this case, people will definitely not say that they think there is no interference."
"Little baby, you are right. This is also one of the key factors why the Galileo navigation system believes that it has a chance to win." Liang Tian fell into memories: "I was already a member of the Beidou people at that time, and I was also very worried. "
"What happened next?"
Fang Yuan knew that Beidou must have survived this hurdle, but under the historical conditions at the time, the possibility of ITU moving towards Beidou was slim.
Liang Tian did not answer directly, but reminded with a bit of pride: "If you remember the second condition so clearly, you can study it carefully again."
Fang Yuan recited it twice more, but no matter how many times he recited it, it was still the same.
"Xiao Fangyuan, if you act like this, you are not suitable for studying law."
Liang Tian hurriedly announced the correct answer before Fang Yuan exploded: "The second condition, before influencing each other, is that all parties applying for the same frequency need to coordinate with each other. But Galileo always , have not coordinated with us. You have not coordinated with us, so we still applied first, why can’t we have priority?”
"Is this okay? Isn't this what you came up with?"
"Why do you think so?"
"Only Liang Tian, a rebellious racing driver, can come up with such words, right?"
"That's really not the case." Liang Tian was amused by Fang Yuan: "This is a simple legal issue. What is written in black and white in the ITU Charter, you can't slap yourself in the face, right? The highest level of negotiation, It’s about using the other person’s logic to convince the other person.”
"That's true." Fang Yuan agreed, "But in the final analysis, the other party should still believe that we can't even handle the rubidium atomic clock."
"Xiao Fangyuan, you are right. Under normal circumstances, within three to five years, we will not be able to build even a shadow of a rubidium atomic clock that can meet the requirements. But our country's astronauts never work alone. "
As Liang Tian spoke, a familiar feeling came over him.
Fang Yuan already had a basic understanding of the chief designer: "Here we go again, nationwide mobilization, right?"
"That's right! After quitting Galileo, Beidou people made up their minds on the last day of May 2005 to replace all four satellite-borne rubidium atomic clocks with domestically produced ones. Within a year and a half, the country mobilized to directly replace the domestically produced rubidium atomic clocks. The error is no more than 1 second in three million years.”
"This is indeed an amazing achievement." Fang Yuan thought for a moment, "In a year and a half, it would have been completely completed in early 2007. You still have to wait until the launch on April 14th, and in the last few hours of the 17th Check and accept the results again. Did you do this on purpose?"
"That's not true. Our Beidou had more than 160 technical problems that needed to be solved at that time. The rubidium atomic clock was the top priority, but it doesn't mean that it can be launched immediately. We definitely hope to launch it as soon as possible. You see, it took Galileo half a month from transmitting to receiving the signal."
"That is to say, the on-orbit debugging time must be half a month, right?"
"It will take at least 7 days."
"If we push forward seven days, the launch would have to be April 10th. Why was it finally postponed to April 14th?"
"This is not our original intention. The first satellite of [Beidou-2] and the rocket carrying the satellite were transported to the launch site on April 2 and 3, and then went to the launch tower to make final preparations before launch. We We conducted three general inspections before and after, and there were no problems the first two times. However, on the third time, the transponder experienced an abnormal signal instability."
"The transponder is a tool for communication between satellites and the ground, right? We also have transponders on the Galaxy Ship."
"That's right. We lost contact with the balloon control center earlier because the magnetic storm disconnected the transponder."
"This was all clearly arranged by Old Man Liang." Fang Yuan returned to the topic, "If this transponder breaks down, even if it transmits it, we won't be able to receive the signal. It's like it's useless, right?"
"Yes."
"Then as you just said, it's unstable, not broken. You can still take a risk."
"I have indeed thought about it, because it is too late even if we calculate the time. If we want to zero in on the transponder problem, we must first go to the top of the sixty- to seventy-meter-high transmitting tower and remove the fairing and The satellite module cannot allow the rocket and satellite to suffer any slight damage."
"What about the second thing?"
"The second thing is that the transponder was developed by me in Shanghai, and the Satellite Launch Center does not have the experimental conditions to reset the problem of the transponder."
"Uh... Old Man Liang, why does it have anything to do with you..."
"I don't know, maybe this is fate. Brother Dong and the others later discussed and gave me three days to solve the problem of the answering machine."
"Then you fly back to Shanghai with the transponder?"
"How could the transponder be brought on the plane? Brother Dong and the others found a place with experimental conditions in Chengdu. I held the transponder in my arms, and the base's special truck driver spent five hours sending me to the laboratory. It took me a whole day. I didn’t sleep a wink for 72 hours, and I don’t even remember how many experiments I did.”
Fang Yuan thought for a while. He had never experienced the matter of not sleeping for 72 hours. He thought it would be quite difficult.
I praised the chief designer in my heart, but what I said out of my mouth became: "You were just thirty at that time, so it was okay to stay up late for three days."
"At that time, I really didn't dare to sleep for a second, because when I went to Chengdu, it was already April 11th, not to mention how much time it would take to debug later. Before April 17th, there was only April 14th. There is the closest launch window, if you miss this, all previous efforts will be in vain, and there will be no chance of subsequent debugging."
Liang Tian explained seriously that Beidou did not deliberately violate the deadline set by the ITU.
Because the launch was late, subsequent on-orbit debugging could only be intensive.
Galileo took half a month, Beidou only three days.
Three days later, at 8 pm on April 17, 2007, the first satellite of Beidou-2 launched the first set of signals to the earth.
Liang Tian and a dozen other receiver design manufacturers lined up the receivers in a row on a huge playground.
As long as there is a receiver that can receive the signal returned by the satellite, ITU's frequency resources and orbital position can be preserved, giving Beidou navigation a legal status.
At eight o'clock in the evening on April 17, 2007, every receiver on the playground accurately received the signal.
From this moment on, China's Beidou has a legal status and begins to enter the world stage with 100% domestically produced core components.
China’s Beidou has gradually become the world’s Beidou.
Galileo, who was full of confidence at first, became anxious again at this time.
Galileo has made representations to Beidou many times, but they don't have many options. After all, it is still the second half of the second condition of the ITU. It has repeatedly stated that sharing the same frequency with China's Beidou will interfere with the operation of Galileo in Europe. .
This kind of negotiation was quite serious at first.
After all, Galileo launched satellites earlier than Beidou, completed their use earlier, and initially had more satellites in the sky.
However, such negotiations gradually lost their meaning as time went by and with the rapid development of China's Beidou.
As of 2012, the Galileo navigation system has launched a total of 6 satellites, and [Beidou-2] just adds a 1 in front of the European Galileo.
China's Beidou, with its 16 leading navigation satellites, has directly expanded the scope of navigation and positioning services to the entire Asia-Pacific region.
Galileo negotiated persistently for several more years, and it was not until 2015 that it officially reached the second condition stipulated by the ITU with China Beidou - China Beidou and European Galileo applied for the same frequency band. The two parties negotiated amicably and believed that in use, There is no mutual interference and the same frequency band can be used together.
From 2007 to 2015, Beidou people have been waiting for this day for eight years.
In the past eight years, Galileo's reasons for negotiation have not changed at all.
The only variable is the Chinese Beidou speed.
