Siheyuan: I eat melons while doing scientific research

Chapter 1410 Feeling Terrifyingly Strong (5k)

I knew it! This kid must have his own considerations beyond those big-picture ideas, otherwise he wouldn't have been so sure that there were more urgent things to do before manned spaceflight.

Gao Zhendong doesn't have the habit of talking nonsense.

Not only him, but other comrades were also very interested.

"Anything else? We've probably exhausted all the possible tasks," one comrade whispered to the person next to him. After everyone's chattered on and on, could anything really be left?

"I don't know, but since he said that, it must be true. You know his style; when has he ever made a false alarm?"

"I've never done that before, but I find it hard to imagine how long and how clever one must think, how broad one's knowledge base must be, to find an application direction after everyone has spoken freely. After all, we've pretty much covered everything that can be done."

"I don't know, we'll find out once we listen."

Amidst the curiosity, Gao Zhendong spoke up.

"I'm considering two areas: remote sensing and communication, but the core purpose isn't communication."

This statement left the comrades a bit confused. Remote sensing is easy to understand; no matter what method is used, it's all for remote sensing. But isn't the core purpose of communication-related technologies communication?

Isn't this similar to saying "Give me a bowl of beef noodles, but no beef and no noodles"?
However, none of the comrades spoke; instead, they waited for Gao Zhendong to continue.

"For remote sensing, my idea is to develop a remote sensing satellite that can operate around the clock, in all weather conditions, with high resolution and a wide swath."

Gao Zhendong's twelve words immediately caused an uproar in the meeting room.

The main thing is these twelve characters, grouped into sets of three, which represent what comrades desire but cannot obtain.

"All day" means without distinction between day and night.

All-weather means regardless of wind, rain, clouds, fog, hail, or snow.

High resolution goes without saying; it's the most basic requirement for remote sensing, but it's often difficult to achieve.

The swath width is also problematic. For optical satellites, swath width and resolution are mutually exclusive because the area of ​​the imaging unit is limited. It is said that a large sensor can capture everything, but if the swath width is too large, a large sensor is not effective either, as it can only contain too much content.

These twelve characters, the first six being usability and the last six being basic performance, basically cover the most basic needs of our comrades for remote sensing technology.

Visible light remote sensing has many advantages, but forget about all-day and all-weather operation. Night, clouds, fog, rain, and snow can all cause it a lot of trouble. Taking some provinces in China as an example, out of 365 days a year, only about one-third of the time is visible. If you take away the nights when the light is insufficient, the amount is even less.

High resolution and wide swath width are problematic not only for visible light remote sensing, but also for the infrared band. After all, no matter how you adjust them, the optical system is limited by current technology.

Comrades originally thought that Gao Zhendong wanted to work on infrared remote sensing, after all, some comrades knew that Gao Zhendong was undoubtedly the number one in China in terms of infrared imaging, especially infrared imaging materials.

"I thought he was going to get into infrared imaging, but I didn't expect him to just not play along with me, look down on me, and find a new path on his own."

"I guess they're leaving infrared technology to us, since we already have a foundation in it, even though he laid that foundation himself."

"I'm truly impressed by this skill."

"So what exactly is he trying to do to achieve this effect?"

"..."

What the other comrades were thinking was another matter, but the comrades in the troops present were excited.

"Can it really have this effect?" He stared at Gao Zhendong, his eyes gleaming.

Gao Zhendong nodded: "Yes, yes, it does, but it's not without its flaws. This kind of remote sensing imaging has no color. But don't worry, although it has no color, it can form a black and white image containing certain detailed elements, not just a pure terrain change. Moreover, when it is developed to a certain extent, it can detect changes in the outline of terrain features, which is three-dimensional imaging."

What he wanted to do was actually very simple: put the SAR radar into satellite!

SAR radar has a very interesting characteristic: its resolution does not change with distance. As long as the radar power is sufficient and the signal-to-noise ratio of the received echo signal meets the requirements, the resolution will not change. It will have the same resolution at 20 kilometers and at 200 kilometers. It is a case of "if it doesn't exist, it doesn't exist; if it exists, it doesn't change."

In fact, the special features of synthetic aperture radar go beyond this. Theoretically, its imaging resolution has nothing to do with wavelength. Different bands are chosen for SAR simply because different wavelengths have different imaging characteristics such as penetration and backscattering.

"What kind of technology is it?" the comrade in the army asked, a question that was actually not appropriate to ask.

Fortunately, the people here were all highly skilled technicians, and SAR technology had been around for a long time and was not exactly a secret. The chief engineer of the committee, who knew a little about it, pulled back the committee leader who wanted to stop him.

“SAR radar!” Gao Zhendong said.

"SAR radar?" The comrades here were all dumbfounded, because none of them were radar experts. They knew absolutely nothing about SAR, if not completely ignorant.

Even among a small number of people working in communications, although they are all radio frequency (RF), there are still differences between different types of RF. After all, even professional radar institutes are still exploring new technologies, so it's normal for non-professionals not to know.

“Yes, this is a new type of radar. In short, it can achieve this effect. Of course, it will be very difficult to put it on a satellite, but I think this direction is worth trying. There are too many benefits.” Gao Zhendong said with a smile.

Before others could react, the comrades in the army reacted the fastest. After all, the word "terrain" that Gao Zhendong had just mentioned was probably the word that touched him the most, apart from a few other words such as firepower and intelligence.

"In other words, if it's successful, this satellite could generate black-and-white photos anytime, anywhere through the atmosphere, and even monitor changes in terrain, or generate global terrain maps at any time?"

The benefits of this are self-evident.

Gao Zhendong nodded and added, "It's not just about topographic maps. If done well, it can also distinguish different landforms such as water, land, and desert based on the different characteristics of the echoes. It can even distinguish the waves on the water surface."

Upon hearing this, the chief engineer exclaimed "Ah!" and remembered that this was the anti-submarine method that Gao Zhendong had mentioned before: using radar to detect the wake of submarines surfacing!
"What resolution can it achieve?" The comrades in the army also thought of many things; this thing can do so many things!
"It's in the 0.5 to 10 meter range. Theoretically, we can do even higher, but right now we're aiming for the 1 to 3 meter range, which is a more suitable range," Gao Zhendong said with a smile.

The other comrades almost swore; even current optical satellites can't necessarily reach 1 meter.

"Hahaha, great, great, great, this is worth doing! Worth doing!" The comrades in the army were overjoyed. This thing, combined with visible light satellites, is simply perfect!
Gao Zhendong laughed and said, "Actually, it's not just you who can use it. Departments such as land, disaster relief, and agriculture can also use it for yield estimation, early warning, post-evaluation, and so on."

The chief engineer was at a loss for words; he still loved agriculture, forestry, animal husbandry, fisheries, and disaster relief.

The comrades in the army didn't mind at all. They thought it was even better this way, because everyone could use it, which would increase its utilization rate. And if everyone could use it, it would mean that it would be easier to get things started.

Hello everyone is really good.

"But at such a long distance, is the radar's effective range sufficient? Can the power and supply be adequate?" Thinking of this, he became somewhat worried. To his surprise, among the comrades here, the one most familiar with radar was this comrade from the military.

Gao Zhendong laughed and said, "There's no need to worry about that. The closest distance to low Earth orbit is only 200 to 300 kilometers. Normally, even a large radar can be effective there. Let's think of a way to hit the radar up there."

As long as there is a launch capacity of a few tons in low Earth orbit, this thing has hope, and this level of launch capacity is exactly the direction we are currently seeking, whether it is a military rocket or a civilian rocket.

High-thrust rockets, as mentioned when we divided the five routes earlier, are a fundamental technology that we were always going to develop. "Hey, I forgot about that. I was just thinking about how high space is, forgetting that low Earth orbit is only so high. But at that distance, won't it cause a decrease in resolution? After all, the farther the distance, the longer the wavelength might need to be, and the signal strength will also decrease."

A distance of 2-300 kilometers isn't far, but it's not close either. It's almost at the limit of current radar's effective range, especially considering that satellite radars can't be too large.

It must be said that those who can attend such technical conferences are quite knowledgeable about technology, and at least they are clear about the general issues.

Gao Zhendong smiled and said, "Don't worry, one of the characteristics of SAR is that, in theory, its resolution is not affected by wavelength, distance, or flight altitude."

All the comrades were surprised, especially those who were more familiar with radar. Could this really be possible?

"Alright! Then we have to get this done! Even if it doesn't go into satellite development, we have to do it! If the aerospace industry isn't willing to get on board, I'll talk to the military and push for its research." The military comrades couldn't contain themselves. Such a good thing, it's one thing not to know, but now that they know, how can they let it go?

He knows his stuff; this thing is incredibly useful! Even if we can't get it to go to satellite, we should at least get it to go to space!

The chief engineer smiled and waved his hand, having already connected all the dots: "No need for that much trouble. There are units that are researching this radar under Comrade Zhendong's leadership, so you don't need to rack your brains. Comrades in the aerospace field, just focus on how to launch this thing into space."

At this point, he couldn't help but applaud Gao Zhendong's strategic layout in the technological system. The most difficult part of this SAR satellite is SAR itself. The satellite itself has a certain foundation. You know, the recoverable satellite technology we exchanged from the north was originally a modified manned spacecraft weighing several tons.

Gao Zhendong has been working on addressing the technical challenges of SAR for some time now, and the research has already entered the preliminary stage.

So it's already underway! No wonder Committee Member Gao seemed so confident.

The soldiers waved their hands emphatically: "Hey! That's great! Committee Member Gao, we've been waiting for your good news!"

They started working on it before this, so it's clear they weren't just aiming for satellite launch, or rather, satellite launch was a side effect. This is a sure thing! We'll definitely be able to use this new type of radar!

Of course, it would be even better if it could be launched into space. After all, at this stage, satellites are generally out of reach of the enemy. In addition, the remote sensing technology has the characteristics of being available 24/7 and 365 days a day, so there are always two eyes in the sky!

Whether it's black and white or not doesn't matter. Even if it's 3 meters or 10 meters resolution as Comrade Zhendong said, it doesn't matter. As long as you can roughly distinguish large ships, then it will be of great use.

No, no, as long as it can estimate production and prevent disasters, it is very useful.

Even the leaders were filled with anticipation for Gao Zhendong's ambitious project and couldn't help but ask, "What about your other communications satellite? A broadcasting and television satellite?"

If we're talking about communication satellites that comrades can think of, but aren't actually for communication, this is probably the only one that comes to mind.

Gao Zhendong shook his head: "No, that's still... I'm not very familiar with it. I'm thinking of something else."

He barely managed to swallow back the words "Let other comrades handle it," but most of the comrades present had more or less guessed what he meant by swallowing back the other half of the sentence.

To be fair, Committee Member Gao was quite considerate, keeping the easy ones and even making a self-deprecating joke to save face.

As for why broadcasting and television satellites are easier than he thought, the comrades are all guessing, but they are all very confident that this is a done deal!
"what is that?"

Gao Zhendong pointed to a map that was a must-have on the wall of any conference room these days: "Navigation!"

Having just upgraded his system, he felt incredibly powerful! At least this matter could be pushed forward; when it would be completed was another matter, but he could take big strides forward.

"navigation??!!!"

Everyone present was shocked, but upon closer examination, they realized that the idea was truly brilliant.

Everyone knows how important navigation and positioning are; it's not just useful in warfare. It's also frequently used in surveying and mapping.

"Don't we already have a single-base station tactical navigation and positioning system?"

Gao Zhendong laughed and said, "But it can't provide all-weather, all-terrain navigation capabilities, and it's greatly affected by terrain. In mountainous areas, it's practically only usable by airplanes in the air, and its use on the ground is very limited. Satellites are different. As the saying goes, the best light shines under the brightest light."

Everyone understands this, but one comrade suddenly remembered something: "Committee Member Gao, are you planning to develop a navigation system similar to Citi's Transit navigation system?"

The Transit system, the first generation of experimental navigation systems before GPS, was used for 30 years, and for a period of time it was used in parallel with GPS.

The navigation system was deployed and delivered to the US Navy last year, but our comrades in the north obtained and exchanged some intelligence, which was not very clear. However, some of our comrades in the aerospace field had heard about it to some extent.

In reality, the system wasn't kept very secret, and by 67 it was partially opened up for civilian use.

Gao Zhendong shook his head: "No, although the details of that navigation system have not been made public, I have studied its orbit. This system has a big problem - the navigation is intermittent and it cannot provide contact navigation. The interval is as short as tens of minutes and as long as more than an hour. This can be fatal sometimes."

Transit's six satellites are all orbiting the Earth at an altitude of approximately 1000 kilometers. However, because there are only six operational satellites, it is considered an experimental system, so the coverage is not good, and sometimes you have to wait for the satellites to come around you.

"Is there another problem?" None of the comrades knew.

"Yes, so I think this is still somewhat unsuitable. I'm considering two other tracks."

"The other two... hiss... could they be GEO?" The comrades were full of surprise.

GEO, geostationary orbit, has the advantage that the satellite remains completely stationary relative to the Earth; the disadvantage is that it's very far away...

36000 kilometers, a distance so great that communication is difficult. The biggest reason for this is that our comrades haven't really developed a proper satellite broadcasting system, even though analog signal communication is relatively simpler at the time.

“Yes, GEO, and IGSO!” Gao Zhendong added.

IGSO, Inclined Geosynchronous Orbit, simply put, is an orbit that circles in a figure-eight pattern at a fixed location, at an altitude of approximately 36000 kilometers.

"Hiss..." The comrades gasped again.

"My plan is to first use two GEO satellites for basic navigation, and then launch an IGSO satellite later to provide signal enhancement." Gao Zhendong did not mention how the communication problem was solved, but instead announced his orbital plan.

"Why use this relatively complex orbital system?" Although three satellites seem simpler, the fact that three satellites use two orbits puzzled the comrades.

“I only consider providing navigation for our entire territory and some surrounding areas, so two GEO satellites can provide basic navigation and short message communication services. The IGSO satellite is used to improve signal coverage in high-latitude areas of our country by using its figure-eight orbit. It would be good to have it, but if it is not available, it will not affect the provision of basic services for the time being.”

Another drawback of GEO is that it is located above the equator, so its signal coverage at high latitudes is not very good.

Gao Zhendong stood up, casually drew a ball and a general area on the blackboard, then added a few dots and drew an "8" shape resembling a little bee dancing.

This satellite and orbit combination scheme is actually the result of Gao Zhendong combining the first and second generation of our later satellite navigation systems and limiting the service area to our surrounding area.

Two GEO satellites form the foundation of the first generation, while one IGSO satellite is content from the second generation. This is almost the most cost-effective and reasonable method that Gao Zhendong could come up with: active positioning. Although it is still a bit inferior to the passive positioning of the third generation, active positioning is basically sufficient these days.

(End of this chapter)