Chapter 1090 20 Minutes of "Quasi-Live Broadcast"

Shen Junrong's hand holding the teacup suddenly stopped in mid-air.

It wasn't until he was burned by the transmitted temperature that he hurriedly retracted his hand and placed the cup in front of Chang Haonan:

"So fast?"

He asked with a look of astonishment:

"But, the launch plan..."

You know, it's only mid-September.

The launch on October 15th can only be regarded as a tentative date.

After all, no one dares to guarantee that the weather conditions will be suitable for launch a month in advance.

If there are any temporary adjustments, all the relay plans will be drastically changed.

It would be fine if it were just a paper modification, but due to the limited effective coverage of the small micro, it would also involve issues such as antenna pointing and even satellite attitude correction.

"Of course it is calculated based on the existing launch time."

Chang Haonan smiled and picked up the cup:

"However, according to our plan, the Qingluan satellite group will wait until 8 hours before launch before starting attitude adjustment... So even if the plan changes, it doesn't matter, it will not affect the operation of the satellite itself."

This answer made Shen Junrong immediately startled, and then he quickly opened the briefcase on the coffee table without even caring about his burned fingers, took out the easily visible folder from it, and started flipping through it quickly.

The entire plan is of course very long.

But the core content is actually less than five pages.

Therefore, in just ten minutes, Shen Junrong saw the end.

As the pages turned, the expression on his face changed from shock to solemnity, and then to a bit of confusion.

After thinking for a while, he went back and read these pages again.

However, the confusion on his face did not lighten at all.

Naturally, this revolving lantern of expression changes did not escape Chang Haonan's eyes, so he put down his teacup and asked with concern:

"Mr. Shen, is there anything wrong with my plan...?"

Shen Junrong raised his head:

"No...no, there is..."

After some rather confusing expressions, he finally organized his words:

"It's not that you have a problem, it's that I have a question to ask you..."

Chang Haonan almost burst out laughing when he first heard this sentence pattern. It took a lot of effort to finally hold it back and switch back to a serious expression:

"You said."

Shen Junrong immediately turned to one of the pages of the plan:

"This part of satellite attitude adjustment... It might be a little difficult to determine the new attitude of all four stars in such a short time, right?"

As an experienced engineering expert, his questions get to the point:

"Of course I'm not questioning your calculations. If this is the Dongfanghong 4 platform, there is indeed no problem, but yours is a small satellite. The attitude sensor of the lightweight platform is limited by size and function, and its performance is difficult to match that of traditional Compared with aerospace-grade components, it generally requires multiple rounds of calibration to ensure sufficient pointing accuracy..."

Obviously, although the Qingluan satellite group itself is not subordinate to the manned space project, Shen Junrong has been paying attention to the former during this period.

At least, even the parameters of the sensors used on the satellite are understood.

However, using a lightweight and low-cost attitude sensor configuration of magnetometer + sun sensor + gyroscope to efficiently determine the satellite attitude was originally one of the key projects of Qingluan system testing——

Aerospace-grade components are accurate and reliable, but the way they are manufactured in precious metal packages makes them expensive.

It is simply impossible to reduce it to a level that can be applied on a large scale.

Moreover, the output cannot keep up.

Therefore, Chang Haonan immediately explained:

"If the attitude is determined directly based on the measurement values ​​of the attitude sensor through a deterministic algorithm, it is indeed difficult to overcome the impact of measurement errors on the accuracy of attitude determination."

"However, you can first use the Gauss-Newton algorithm for preliminary solution..."

As he spoke, he suddenly looked around, as if he was looking for something.

Shen Junrong quickly gestured to Zhang Weiyong who was waiting next to him.

The latter quickly handed over pen and paper.

"Like this...convert the 6-dimensional observations of the magnetometer and solar sensor into optimal quaternions, thereby reducing the observational degree of freedom from 9 dimensions to 7 dimensions, and then use the optimal quaternions to combine the gyro data as Observed quantities, using the attitude quaternion and the angular velocity in the inertial frame as state quantities for UKF filtering, can minimize the impact of measurement errors and improve the attitude solution accuracy..."

While describing, Chang Haonan roughly listed the calculation methods of the filtering state equation and Kalman gain matrix.

Of course, the specific results cannot be calculated by the human brain.

Zhang Weiyong has been conducting state simulations on Shuguang-3 since the second half of last year, and it was not until shortly before the launch of the satellite that all parameters were finally determined.

After finishing writing, Chang Haonan put the pen aside calmly:

"Although the accuracy is still impossible to match that of large platforms, medium-orbit satellites are not particularly sensitive to attitude, and even if four sets of backups are included, the cost of the entire attitude positioning system is less than 10% of the traditional solution. , enough to be put into large-scale application in the future..."

"Four sets of backups?"

Shen Junrong has never seen the complete design plan of Qingluan satellite.

Chang Haonan smiled and nodded:

"There is no way. Due to cost and construction period considerations, the satellite-based computer does not use aerospace-grade products. If we don't prepare a few sets of backups, how can we achieve the reliability required by the satellite?"

His ultimate goal obviously cannot be just four satellites——

Given China's infrastructure level, the value of constellations like OneWeb or Starlink that are directly oriented to civilian ground terminals is indeed questionable.

But even as a communication bridge between other satellite networks, the number of terminals connected to medium and low orbit communication satellites cannot be underestimated.

Shen Junrong had already guessed this, but after hearing this, he realized that he seemed to have greatly underestimated the ambition of the young man in front of him.

He stared blankly at the paper filled with formulas in his hand for a while, then sighed softly:

"When you proposed to the Science and Technology Commission to establish the Equipment Industry Department, I felt that you had a long-term vision and would not stop at trivial matters..."

"The result now seems to be a bit underestimated..."

Shen Junrong's last year as deputy director of the Science and Technology Commission coincided with the time when Chang Haonan first entered Ding Gaoheng's field of vision.

The first and only time the two met was at an enlarged team meeting to discuss whether the Equipment Industry Department should be established.

At that time, the latter could only be regarded as a young technician who had a certain influence on decision-making.

But in just a few years, it has grown into an existence like a towering tree...

After the short emo, Shen Junrong quickly returned to the topic:

"Now that the technical feasibility has been determined, the next step is the specific plan."

Having said this, he was suddenly silent for a while when he should have relaxed.

Then he stood up and walked to the office window with his hands behind his back:

"The News Center has prepared the script and a full broadcast plan, but it has not yet been finalized whether the entire mission will be included in the live broadcast plan."

"The current hesitation of superiors is that since the launch of the ChinaSat 7 communication satellite failed, due to safety considerations, the space launch mission will no longer be broadcast live in principle... But the nature of the mission this time is different after all, plus there are still There is excellent content that can maintain the in-cabin picture for a long time. If all the broadcast pictures are used, the publicity effect will be greatly reduced..."

Hearing this, Chang Haonan suddenly became energetic:

"The live broadcast does not necessarily need to be at the launch site. It can also be carried out at the receiving terminal of the Qingluan constellation. Anyway, the focus is on the continuous images in the cabin... In addition, the relay communication maintenance time is about 30-40 minutes, but it still needs Cut off some sensitive content that is inconvenient to display, so the best way is to delay the live broadcast for 8-10 minutes, so that you can still reserve about 20 minutes of content. "

"I have seen the indicators of the image and voice system in the Shenzhou 5 spacecraft. With the performance of the Qingluan constellation, it can completely ensure the smooth flow of data transmission. In addition, Comrade Guo Lin also mentioned the weather problem in Beijing to me, so we A preliminary plan will be kept in Haojing, but two teams need to be dispatched accordingly just in case..."