"Start the Beidou navigation and positioning test!"

Chen Zhongyan was in the hall of the satellite control center, constantly carrying out various tests.

After the Beidou Phase I system entered the geostationary orbit, it has relied on its own power to move to a predetermined position.

And unfurled its own solar wing sails, officially began work.

The first phase of Beidou mainly provides positioning, communication and timing functions.

In order to achieve high accuracy in the positioning function, it is necessary to rely on a highly accurate atomic clock.

Because of the realization of the Beidou positioning function, the user's location is simply calculated through the time difference between the two satellites receiving ground signals.

Therefore, if the rubidium atomic clock error on the two satellites exceeds 1ns (billionth of a second), it can be 0.3 meters different for ground positioning.

The reason why the positioning accuracy of the Beidou Phase III navigation system is much higher is largely due to the fact that the domestic rubidium atomic clock and cesium atomic clock have been localized, and the accuracy of timing is much higher.

The two rubidium atomic clocks on Beidou-1 and Beidou-2, because China is still relatively backward in this regard, cannot be produced independently, and can only be imported from abroad at a high price, and even so, these two rubidium atomic clocks can only barely meet the application requirements.

"The ground control system has obtained the positioning data sent back by the Beidou-1 and Beidou-2 satellites."

An engineer in a blue and white uniform handed over the latest positioning information sent back by Beidou to Chen Zhongyan.

"So much to get out?!"

Chen Zhongyan looked at the data report in his hand and frowned.

Although it was expected that the positioning accuracy would not be too high before the satellite went into the sky, after the real situation came out, it was still a little shocking.

The positioning accuracy of the Beidou Phase I positioning and navigation system can only be maintained within the error range of 20-100 meters.

You must know that at this time, the GPS positioning and navigation system of Eagle Sauce can achieve an accuracy of 10 meters.

"Is it really a problem with the atomic clock?"

Chen Zhongyang looked at the errors of several positioning punctuation points, and couldn't help but think in his heart.

"Has the timing function been tested?"

Hiding the question of the atomic clock in his heart, Chen Zhongyan asked about the timing.

"Tests are underway, and results will be available right away."

After the engineer finished speaking, he immediately returned to his job and continued to work.

Looking at the busy crowd, Chen Zhongyan fell into deep thought.

Atomic clocks, in fact, are the big problems that navigation systems are bound to face.

At this time, the road to domestic rubidium atomic clocks is not very smooth, and I don't know how many years it will take to really realize localization.

And when the domestic Beidou navigation system is really going to be built in the future, it is still a question whether people will continue to sell you rubidium atomic clocks!

"Old Chen, the timing accuracy results are out."

At this time, another engineer ran over and handed over the timing accuracy results of the first phase of Beidou to Chen Zhongyan.

Satellite timing accuracy is actually controlled by the theory of relativity.

According to the time dilation effect in Einstein's theory of relativity, the faster an object moves, the slower time will be.

Beidou satellites fly at a speed of 4km/s in space, and according to the special theory of relativity, the daily time will be slower: (4×4)/2(c×c)×60×60×24=7.68 microsecondsThe satellite is 20,000km above the ground, and the gravitational force is much smaller than that of the ground, and according to the general theory of relativity (the difference between the gravitational potential of the satellite and the ground)/(the square of the speed of light), the daily time will be faster: [(GM/6371km)-(GM/26371km)]/c/c=45.58 microseconds, that is, satellites in the sky will be 38 microseconds faster than the ground every day.

In other words, if the satellite does nothing in the sky every day, it will produce an error of 38 seconds, so if you want to maintain the accuracy of the time, you need the atomic clock to calibrate the time every 1.5 seconds.

"The difference between the timing accuracy and the experiments we did on the ground is not very large, and the error is about 20ns."

The engineer looked at the timing accuracy report in Chen Zhongyan's hand and said helplessly.

"Well, it's true that it's not much different from the experiment we did before, but this is a two-way timing accuracy, and the one-way timing accuracy is still a little unsatisfactory!"

Chen Zhongyan agrees with the engineer's statement, but also points out the difference.

Generally speaking, the one-way timing function does not require the Beidou terminal on the ground to send signals to the satellite, and only needs to accept the timing signal broadcast by the Beidou satellite.

Although the accuracy of this timing method is lower, it does not need to occupy the communication frequency band of the Beidou satellite system.

The number of users that Beidou can accept at the same time is limited, no more than 540,000 users per hour.

Most of them are also used in a variety of positions that require precise timing.

It is simply not possible for most industries or units to use it.

Therefore, the one-way timing accuracy is the real accuracy of Beidou timing!

"Old Chen, with our current conditions, it is the limit that we can do this." The engineer feels that achieving such accuracy is almost the limit of the entire Beidou project team.

You must know that if other countries were to do it, the accuracy would definitely be much lower than theirs if they used atomic clocks of this precision.

Chen Zhongyan also knows that everyone has paid a lot of time and energy to do this.

So I didn't blame too much, but comforted a little:

"Everyone has worked hard for the Beidou in the sky!"

"The results of the communication function test are estimated to be coming out soon, so you can get busy."

At this time, Chen Zhongyan walked next to the engineer in charge of communication function testing.

Looking at the data exchange between the stars and the ground, it is displayed on the big-ass computer that is still very backward.

The communication function of the Beidou system can be regarded as the first in China.

At this time, two sets of satellite systems have been built, whether it is Maozi's GLONASS system or Yingchan's GPS system.

They all have no communication function.

However, because the low-orbit satellite communication system has been officially approved and the construction work has begun, the communication function that was originally retained in the Beidou Phase II system that was originally built later has been cut.

Only the positioning and timing functions are retained.

"Old Chen, the test results are even better than the experiments we did on the ground!"

The female engineer in charge of the communication test turned her head and looked at Chen Zhongyan very happily.

"The transmission of 36 Chinese characters in a single time, the transmission of 120 Chinese characters in a row, and the transmission of 36 Chinese characters in both directions have all achieved the results we achieved in the ground trial."

"However, the transmission response is a little better than when we tested it before."

Chen Zhongyan pushed his glasses and said happily as he looked at the results on the screen.

Because of the launch three years ahead of schedule, the world's Beidou has seized a better orbit.

Therefore, the transmission effect of the signal is also better than in the previous life.

(End of chapter)