Chapter 752 That’s easy!
The participants at the meeting certainly agreed with Gao Zhendong's statement, but they were not clear about the specific technical details about what technology could achieve this effect.

"Zhendong, tell me in detail." The leader of the Defense Work Committee was very interested. Since it was a discussion and evaluation, the Defense Work Committee wanted to know all the details, which would be more conducive to long-term planning.

Gao Zhendong nodded: "Let's put aside things related to communication technology for now. Assuming that the bandwidth is fixed and we want to transmit a picture, while ensuring the quality, then naturally the smaller the picture, the better, right?"

Anyone with a normal mind would not object to this conclusion. Moreover, those present were all experts in their respective fields and they all nodded in agreement.

“Then how can we reduce the size of an image while ensuring the quality? Note that it should be automatic reduction, without the need for human intervention.” Otherwise, how can we say that everyone present here is top-notch? A comrade quickly grasped the key point. It has to be automatic. If human intervention is required, there is no point.

However, this kind of technology does not exist in China at all.

When the leader of the Defense Work Committee heard this, he felt more confident. If he guessed correctly, Gao Zhendong should have been prepared. He didn't know anything else, but this thing sounded like it was related to computers and automatic control. Since it happened to Gao Zhendong, he had asked the right person.

As expected, Gao Zhendong smiled happily: "It just so happens that not long ago, I led a group of people to develop a set of image lossy compression algorithms and related software modules. Now they have been put into trial use on a small scale, and the effect is very good. Although it is lossy, it has basically no effect on the human eye's interpretation. The compression rate can be as high as 50%~90%. Compared with color photos, its volume will be smaller."

The comrades who are engaged in file compression have already developed the image compression algorithm given by Gao Zhendong, but this kind of thing is too small for Gao Zhendong and he usually doesn't remember it.

Contrary to what the leaders of the National Defense Work Committee had expected, the people present were all scientific experts, but they did not have a deep understanding of this field. When they heard Gao Zhendong's words, they were pleasantly surprised and their reactions were unanimous: "Really?"

It's not that I don't believe Gao Zhendong, but I don't believe my own ears. When did China have such a new technology without any news? Although I know that China has made great achievements in computer technology in the past two years, I didn't expect such an application, which can even be said to be a mathematical algorithm, to have such development.

Image compression algorithms can be said to be closely related to computers, but even more closely related to mathematics. Even if one is good at computers, his or her mathematics may not necessarily keep up.

Gao Zhendong nodded: "Really!"

The leader of the Defense Work Committee smiled and said, "Comrades, this is Comrade Gao Zhendong."

This was the first time he introduced Gao Zhendong's full name at the meeting, and he was quite proud to introduce it. After all, if you only called him "Zhendong", you wouldn't really know who he was, as there were so many people with this name these days.

Ah, the big shots present all nodded and understood, it turned out to be him.

It is true that hearing about someone is not as good as meeting him/her in person, and there is no false reputation behind such a great person.

Gao Zhendong is best known for his computer skills. I didn't expect that this comrade is not only good at computers, but also has some skills in applied mathematics.

Many of these comrades are scientific experts who have a good understanding of computers and applied mathematics and do not confuse the two.

Seeing everyone nodding, Gao Zhendong gave an example: "We have done an experiment. A clear natural photo, converted into a black-and-white picture with a resolution of 960*540, can be converted into a little over 100k bytes while maintaining high-definition details. This size, even if transmitted at a low rate of 1200bps, takes about 800 seconds, or less than 15 minutes."

Although the total pixels of 960*540 are only one-fourth of the 1080P resolution, in this day and age, if the format is appropriate, it can be a full-fledged high-definition picture.

But now some comrades are a little bit unbearable, after all, they are not in this profession, and this thing is still a relatively new thing. You are full of professional terms, are you going to take the postgraduate entrance examination?
Although I didn't understand it completely, I at least understood one thing: a photo with good quality and detailed information can be transmitted in 15 minutes using the current relatively slow transmission speed.

"If we can reach this speed, this thing can really be done. If the orbit is suitable, we can return once every 40 minutes to 2 hours, and at least take a photo of the place we are interested in!"

"Don't even think about taking the photo once and sending it back. Even if you take the photo once and send it back once, 4 hours is acceptable."

"You have very high expectations. How can you estimate the yield of crops every four hours? Even natural disasters don't necessarily require such a high speed."

"Well, don't worry about it. Anyway, I think this is indeed worth considering."

"..."

Not to mention them, the ones with the brightest eyes are the leaders and chief engineers of the Defense Work Committee.

Fuck, I got sucked into this guy again. I really want this thing...

However, some comrades calmed down after their excitement and became a little worried. "But our optical technology..." This is the most fatal point.

However, some comrades did not mind: "Hey, even if we can't take detailed photos, it's good to take satellite cloud pictures. We may not be able to take a full picture at this orbital height, but at least we can take clear pictures of parts. This can really be used for agricultural production and people's lives, hahahaha."

This sentence is very clever and made everyone laugh.

Gao Zhendong is not too worried about this. At least there is no problem with the satellite cloud map, and the capability of the Northeast Institute of Optics is not bad. Maybe there will be some surprises. Anyway, the 3-micron lithography machine gave Gao Zhendong a big surprise. Sometimes the reason for not producing something is that there is no demand, not that there is really no capability.

With the atmosphere getting a lot more interesting, everyone started to think deeply about the feasibility of photographic satellites.

"But there is a problem. Our current camera technology cannot support converting photos into images that computers can recognize, right?"

There was no CCD in those days, but this obviously did not pose any problem for the masters present.

"There is still a way. The camera tube can solve the problem. We can read the analog signal on the target surface of the camera tube and convert it into a digital signal."

As long as there are televisions, there are cameras. However, the cameras at that time were different from the later ones. They can be regarded as the cathode ray tube reversed.

A cathode ray tube displays images by hitting a phosphor with an electron beam, while a camera tube hits light onto a photoelectric material to obtain electrons, which drive an analog circuit to record a video signal. However, this analog signal cannot be used for direct digital transmission, let alone computer storage.

"This won't work. Theoretically, there is no problem. If the resolution is not enough, it can be improved by customizing the target surface and the optical scanning system. However, the photoelectrons in the camera tube disappear very quickly, and a very high-speed AD converter is required to record the image. Otherwise, even if a low-resolution standard TV signal is used for analog transmission, its transmission bandwidth is as high as 8MHz, and our current communication technology is still a bit unable to cope with it."

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8M? Hiss…

Anyone who has some knowledge of communication technology will feel as if a bucket of cold water has been poured over their heads. This speed, even in low-Earth orbit, is far beyond the capabilities of current communication technology.

Some comrades thought quickly: "We just want still photos. We don't need the standard TV signal speed of 25 frames per second, right? Isn't it enough to transmit only one frame within a certain period of time?"

It seems that the Defense Work Committee originally wanted the satellite to be used for communications or radio and television work, otherwise there would not be so many comrades from related professions present when discussing the onboard payload, and they all looked very familiar with each other.

"The problem is not here. The main problem is that we still need high-speed AD. The camera tube signal can only be maintained for so long."

"Add a subsequent circuit to extend the signal holding time and then transmit it back?"

"In theory, it is possible, but such technology is not yet available."

While everyone was scratching their heads over this problem, Gao Zhendong had already completed the search. Compared to creating something out of nothing, he really saved this thing. Thanks to his mentor in his previous life, who cursed people in a rather unpleasant way, he was able to save a lot of strange and weird things.

Gao Zhendong raised his hand and everyone looked at him. This matter seemed to be related to computers. Since he had achieved results in image compression and storage, perhaps he also had ideas in image generation?
Although this connection is very far-fetched, he has raised his hand, so it should not be in vain.

"Dear experts, there is no need to transmit it back. We can store the electrons and keep them on the target for a longer period of time. This time is enough for the low-speed AD to complete the scan. After the scan is completed and the digital image is converted, it can be slowly transmitted back."

Hmm? Storing electrons? What kind of weird idea is this? This thing can store electrons? The target surface is not a capacitor.

"Comrade Zhendong, are you sure?" The leader of the Defense Work Committee knew him. He was really good at optoelectronics. Aren't infrared sensors and thermal imagers all made of optoelectronic materials? The comrades present didn't know this, but he did. Materials were also his strong point.

Gao Zhendong smiled and said, "Yes, in fact, if you want to store electrons, all you need to do is require the target surface material to have the highest possible resistivity while meeting the photoelectric performance requirements, so that the loss of photoelectrons is as slow as possible."

The first part of this statement is correct. Even if you are not a materials expert, as long as you have some knowledge of electricity, you will understand it immediately. The only problem is that the last sentence is not very humane. "That's all"? Just these two words can kill a lot of people.

"The problem is, we don't have this kind of high-resistivity target surface photoelectric material." This is the biggest problem. We don't have this thing, so those two words are simply infuriating to say.

Upon hearing this comrade's words, Gao Zhendong hadn't laughed yet, but the leader of the Defense Work Committee smiled first. So this was the problem?
That's easy! Especially when Gao Zhendong took the initiative to talk about this matter.

(End of this chapter)