Chapter 752 This is easy to handle!
Regarding Gao Zhendong's statement, the participants definitely recognized it, but in terms of specific technical details, it was not clear what technologies could achieve this effect.
"Zhendong, talk about it in detail." The leader of the National Defense Working Committee was very interested. Since it was a discussion and evaluation, the National Defense Working Committee wanted to know all the details, which would be more conducive to long-term planning.
Gao Zhendong nodded: "Let's put aside the communication technology-related things first. Suppose that under the condition of a certain bandwidth, we want to transmit a picture. Under the condition of ensuring the quality and usability, then naturally the smaller the picture, the better, right? ?”
No one with a right mind would object to this conclusion, not to mention that the people present were all masters in their respective fields, and they all nodded.
"Then how can we reduce the size of an image while ensuring that the quality is usable? Note that it is automatically reduced and does not require manual intervention." Otherwise, everyone here is top-notch. Some comrades are very The key point is grasped quickly. It must be automatic. If it requires human intervention, it is meaningless.
This kind of technology is currently not available in China.
When the leader of the National Defense Working Committee heard this, he calmed down. If he guessed correctly, Gao Zhendong should have been prepared. He said he didn't know anything else, but this thing sounded related to computers and automatic control. Gao Zhendong has the right person to ask.
As expected, Gao Zhendong smiled very happily: "It just so happened that not long ago, I led people to develop a set of image lossy compression algorithms and related software modules. Now they have been put into trial on a small scale, and the results are very good. , although it is lossy, it has basically no impact on the human eye’s interpretation, and the compression rate can be as high as 50%~90%. Compared with color photos, its size will be smaller.”
The comrades who are engaged in file compression have already figured out 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 very much.
Unlike what the leaders of the National Defense Working Committee had expected, everyone present here can be said to be scientific experts, but they don’t know much about this field. Hearing Gao Zhendong’s words was an unexpected surprise, and the reaction was super unanimous: " Really?”
It's not that I don't believe Gao Zhendong, but I don't believe my own ears. When did this new technology appear in China quietly? Although I know that domestic computers have made great achievements in the past two years, I really didn't expect such development in this kind of application, which can even be said to be a mathematical algorithm.
It can be said that the image compression algorithm has a lot to do with computers, but it has more to do with mathematics. If computers are powerful, mathematics may not be able to keep up.
Gao Zhendong nodded: "Really!"
The leader of the National Defense Working Committee smiled: "Comrades, this is Comrade Gao Zhendong."
This was the first time he introduced Gao Zhendong's full name at the venue, and he was very proud of it. After all, it’s just called “Zhendong” and I really don’t know what it means. There are so many people with this name these days.
Ah, the big guys here nodded and understood, it turned out to be him.
As expected, it is better to meet than to be famous, and there is no empty person under the great reputation.
Gao Zhendong is best known outside for his computer skills. Unexpectedly, this comrade is not only good at computers, but also has a few skills in applied mathematics.
Quite a few of these comrades are masters of science, and they know very well about computers and applied mathematics, and they will not mix them up.
Seeing everyone nodding, Gao Zhendong gave an example: "We have done experiments. A clear natural photo is converted into a black and white picture with a resolution of 960*540. It can be 100k bytes while maintaining high-definition details. At this size, even if it is transmitted at a low rate of 1200bps, it will take about 800 seconds, which is less than 15 minutes.”
Although the total pixels of 960*540 are only a quarter of the 1080P resolution, in this day and age, if the format is suitable, it can be a decent high-definition picture.
But now some comrades are a little bit unbearable. After all, they are not professionals in this field, and this thing is still relatively new. You are full of professional words, do you want to take the postgraduate entrance examination?
However, although I didn’t fully understand it, I at least understood one thing. A photo with good quality and maintained details can be transferred in 15 minutes using the existing relatively low-speed transmission rate.
"If we can have this speed, this thing can really be done. If the track is suitable, we can return once in 40 minutes to 2 hours. At least we can take a photo of the place of interest!"
"Don't say you take a photo and send it back. Even if you take a photo and send it back once, 4 hours is still acceptable."
"Your demands are really high. There are no crops that need to be estimated every four hours. Natural disasters don't necessarily require this speed."
"Hey, 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 National Defense Work Committee.
Damn it, I got sucked into this kid again, I really want this thing...
However, some comrades calm down after being excited and become a little worried. "But our optical technology..." This is the most important thing.
However, some comrades are indifferent: "Hey, even if you can't take too detailed pictures, it's better to take satellite cloud pictures. You may not be able to take full pictures at this orbital height, but at least you can take partial pictures clearly. This can really be used in agriculture." Production and people’s lives, hahahaha”
This sentence was very spiritual and made everyone laugh.
Regarding this, Gao Zhendong is not too worried. At least the satellite cloud images are fine, and the capabilities of the Northeast Optics Institute are not bad. There may be surprises. Anyway, they give Gao Zhendong a lot of 3-micron lithography machines. The big surprise is that sometimes I don’t come up with something because I don’t have demand, not because I really don’t have the ability.
Now that the atmosphere has reached this point, everyone's interest has aroused and they have begun 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 is no CCD these days, but this obviously does not trouble the experts present.
"There is still a way. The camera tube can solve the problem. Just read the analog signal on the target surface of the camera tube and replace it with a digital signal."
As long as there is a TV, there is a camera, but the camera at this time is different from the later ones. It can be regarded as the reverse of the picture tube.
The picture tube hits the electron beam on the phosphor to develop the image, while the camera tube hits the light on the photoelectric material to obtain electrons, which drives the analog circuit to record the video signal. However, this analog signal cannot be used for direct digital transmission, let alone Used for computer storage.
"This is not possible. There is no problem in theory. The resolution is not enough. It can also be improved by customizing the target surface and optical scanning system. However, the photoelectrons of the camera tube disappear very quickly, and a very high-speed AD converter is required to record the image. Otherwise, even if low-resolution standard TV signals are used for analog transmission, the transmission bandwidth is as high as 8MHz, and our current communication technology is still a bit unable to withstand it. ”
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8M? Hiss...
Any comrade who knows about communication technology is like a bucket of cold water being poured over their head. This speed, even in low-Earth orbit, is far beyond the capabilities of current communication technology.
Some comrades' heads were spinning very fast: "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 only transmit one frame in a certain period of time?"
It seems that the National Defense Working Committee originally wanted the satellite to be engaged in communications or radio and television work. Otherwise, when discussing the payload on the satellite, there would not be so many comrades in related professions, and they would all look familiar.
"The problem is not here. The main thing is that we still cannot do without high-speed AD, and the signal retention time of the camera tube is only so long."
"Increase the post-stage circuit to extend the signal holding time and then transmit it back?"
"Theoretically it is possible, but such technology is still not available yet."
Just when everyone was scratching their heads about this problem, Gao Zhendong had already completed the search. Instead of making things out of nothing, he really saved this thing. Thanks to his mentor who was a bit ugly in his previous life, he saved a lot of weird things. thing.
Gao Zhendong raised his hand, and everyone looked at him. This matter seemed to be related to computers. Since he had achieved results in compressing and saving pictures, maybe he also had ideas in generating pictures?
Although this connection was very reluctant, he raised his hand, so he probably gained nothing.
"Experts, there is no need to send it back. We can store the electrons and keep them on the target surface for a while. This time is enough for the low-speed AD to complete the scan. After the scan is completed and turned into a digital image, it can be sent back slowly. .”
Um? Storing electrons? What kind of strange idea is this? Can these things be saved? The target surface is not a capacitor.
"Comrade Zhendong, are you sure?" The leader of the National Defense Working Committee knows him. He is really good at optoelectronics. Infrared sensors and thermal imaging cameras are all optoelectronic materials. The comrades here don't know that, but he knows that materials are also his strong point.
Gao Zhendong smiled and said: "Yes, in fact, if you want to store electrons, it is nothing more than requiring the target surface material to have the highest possible resistivity while meeting the photoelectric properties, so that the loss of photoelectrons can be as slow as possible."
The previous words are all correct. Even if you are not a material person, but as long as you know about electricity, you can understand it immediately. The only problem is that the last sentence is not very personable, "just"? Just these two words can kill a lot of people.
"The problem is, we don't have such high-resistivity target surface optoelectronic materials." This is the biggest problem. There is no such thing, so those two words are simply annoying to say.
Hearing this comrade's words, before Gao Zhendong smiled, the leader of the Defense Working Committee showed a smile first. So what's the problem?
That would be easy! Especially when Gao Zhendong took the initiative to talk about this matter.
(End of chapter)