Chapter 1090 20 Minutes of "Quasi-Live Broadcast"

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

It was not until he felt burned by the temperature that he hastily 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..."

Remember, it's only mid-September.

The launch date of October 10 is only a tentative date.

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

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

It would be fine if it was just a paper modification, but since the effective coverage range of small and micro satellites is limited, it will also involve issues such as antenna pointing and even satellite attitude correction.

"Of course it is calculated according to the existing launch time."

Chang Haonan picked up the cup with a smile:

"But according to our plan, the Qingluan satellite cluster will wait until 8 hours before launch to start attitude adjustment... So even if the plan changes, it doesn't matter. It won't affect the operation of the satellite itself."

This answer made Shen Junrong stunned immediately. Then, without even caring about his burned fingers, he quickly opened the briefcase on the coffee table, took out the folder that was visible at a glance, and began to flip through it quickly.

The entire plan is, of course, very long.

But the core content is actually less than five pages.

Therefore, it only took Shen Junrong more than ten minutes to see the end.

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

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

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

This changing expression naturally did not escape Chang Haonan's eyes, so he put down the teacup and asked with concern:

"Boss 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 for you..."

Chang Haonan almost laughed out loud when he heard this sentence. It took him a lot of effort to hold it back and switch back to a serious expression:

"You say."

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

"As for the satellite attitude adjustment part...Isn't it difficult to determine the new attitude of all four satellites in such a short time?"

As an experienced engineering expert, he asked questions that hit the nail on the head:

"Of course I'm not questioning your calculations. If this was the Dongfanghong-4 platform, there would be no problem. But yours is a small satellite. The attitude sensors on lightweight platforms are limited by size and function. Their performance is difficult to compare with traditional aerospace-grade components. Generally, multiple rounds of calibration are required to ensure sufficient pointing accuracy..."

Obviously, although the Qingluan satellite cluster itself does not belong to the manned space project, Shen Junrong has paid much attention to the former during this period.

At least, we have some understanding of the parameters of the sensors used on the satellite.

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

Aerospace-grade components are indeed precise and reliable, but the manufacturing method of precious metal packaging makes them expensive.

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

Besides, the production can’t keep up.

Therefore, Chang Haonan immediately explained:

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

"However, we can use the Gauss-Newton algorithm to perform a preliminary calculation..."

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

Shen Junrong quickly gestured to Zhang Weiyong who was waiting nearby.

The latter quickly handed over paper and pen.

"Like this...convert the 6-dimensional observations of the magnetometer and sun sensor into the optimal quaternion, thereby reducing the observational degrees of freedom from 9 dimensions to 7 dimensions. Then, use the optimal quaternion combined with the gyro data as the observation quantity, and use the attitude quaternion and the angular velocity in the inertial system as the state quantity for UKF filtering. This can minimize the impact of measurement errors and improve the accuracy of attitude solution..."

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

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

Zhang Weiyong has been conducting state simulation on the Dawn-3 since the second half of last year, and finally determined all the parameters shortly before the satellite launch.

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

“Although the accuracy is still not comparable to that of large platforms, medium-orbit satellites are not particularly sensitive to attitude. Moreover, even with four sets of backups, the cost of the entire attitude positioning system is less than 10% of the traditional solution, which is enough for large-scale application in the future…”

"Four sets of backup?"

Shen Junrong has not seen the complete design plan of the Qingluan satellite.

Chang Haonan smiled and nodded:

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

His ultimate goal obviously cannot be just four satellites——

Given China's level of infrastructure, the value of constellations like OneWeb or Starlink that are directly aimed at 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 guessed this a long time ago, 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 piece of paper filled with formulas in his hand for a while, then sighed softly:

"When you proposed to the Science and Technology Commission to set up an Equipment Industry Department, I felt that you had a long-term vision and would not stop at some small things..."

"It seems that I underestimated it..."

Shen Junrong's last year as deputy director of the Science and Technology Commission happened to be the time when Chang Haonan first came into Ding Gaoheng's sight.

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 was just a young technician who had a certain influence on decision-making.

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

After a brief emo moment, Shen Junrong quickly returned to the topic:

"Now that the technical feasibility has been confirmed, the next step is to come up with a specific plan."

Having said this, he, who should have relaxed, suddenly fell silent for a while.

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

"The news center has prepared the script and the complete broadcast plan, but it has not yet been finalized whether the entire mission will be included in the live broadcast plan."

"The reason why the superiors are hesitant is that, since the failure of the launch of the ChinaSat-7 communications satellite, space launch missions are no longer broadcast live in principle for safety reasons... But the nature of this mission is different after all, and there is also excellent content that needs to be maintained for a long time on the cabin screen. If all the screens are broadcast, the publicity effect will be greatly reduced..."

Hearing this, Chang Haonan suddenly became alert:

"The live broadcast does not necessarily need to be at the launch site, it can also be done at the Qingluan constellation's receiving terminal. Anyway, the focus is on the continuous images inside the cabin... In addition, the relay communication can be maintained for about 30-40 minutes, but it is also necessary to cut off some sensitive content that is inconvenient to display, so the best way is to delay the quasi-live broadcast by 8-10 minutes, so that there is still about 20 minutes of content expected."

"I have already looked at the indicators of the image and voice system in the Shenzhou V spacecraft cabin. With the performance of the Qingluan constellation, it can fully guarantee smooth data transmission throughout the entire process. In addition, Comrade Guo Lin also mentioned the weather problem in the capital, so we will keep a backup plan in Gaojing, but we need to send two teams accordingly just in case..."