Chapter 722 Pulse Compression
Gao Zhendong said to the comrades from Factory 1274 who came to cooperate with the test: "After installation, try to engrave a batch of 3 micron standard test masks, and then send them to your factory for packaging. From photolithography to packaging, the whole process must be done. Just finish it.”
The standard test mask has no function. It is a mask for testing whether the 3 micron process is qualified. Now there is no need for any functional chip. Anyway, it can pass the whole process test and prove that the chip technology of 3 micron process already exists.
In response to his request, the comrades of Factory 1274 nodded in agreement. As for why, they didn't care, and it was not their business.
Regarding this matter, Gao Zhendong is gearing up. Everything is ready and all he needs is the east wind. He has been waiting for a long time.
However, photolithography experiments take time. I have spent a lot of time waiting, and I don’t care about this. I can’t eat hot tofu in a hurry.
Gao Zhendong put down what he was doing here and turned back to the office. The staff from the No. 3 Factory Office came to inform him that someone was looking for him.
When Gao Zhendong came to the reception room, he saw acquaintances in front of him, the comrades who worked on the PD radar.
"General Engineer Gao, the test of the flat slot antenna you gave us has been completed, and the effect is very good! It has high gain, low side lobes, and can also perform waveform synthesis to a certain extent!" As soon as Mr. Liu arrived, he brought Gao Zhendong Good news.
Gao Zhendong was overjoyed. This flat-panel slot antenna was based on a paper he found in the system. After thoroughly studying it, he improved and designed it based on the actual radar band we used, and then developed it at the No. 3 Factory. produced.
Although there is definitely no problem with his doctoral thesis, he is still a little worried about whether there will be any problems after improving the design, and he estimates that it needs to be revised.
But I didn't expect it to go so smoothly, which made Gao Zhendong feel a little proud. Brother, I don't just copy, I still have my own stuff.
The success of the flat-panel slot antenna has brought our radar hard conditions to the pinnacle of existing radar technology.
The combination of flat-panel slot antenna, traveling wave tube and digital signal processing device will surely produce greater light.
Regarding the flat slot antenna, Mr. Liu obviously feels that it is not enough. This thing is really easy to use: "We have tested that using the characteristics of the flat slot antenna and electrically sweeping it in the horizontal direction can greatly improve the data refresh rate and performance of our radar. Multi-target processing capabilities! Mr. Gao, this 'whim' you came up with is really amazing!"
Generally speaking, enemy aircraft groups will generally be distributed in several identical altitude ranges in a single actual combat, so when dealing with a certain type of enemy aircraft, their altitudes are generally the same.
In this way, the scanning speed and demand in the vertical direction are not urgent, but scanning in the horizontal direction is very important.
So when Mr. Liu realized that this flat-panel slot antenna could really achieve electrical scanning in a certain direction, he did not hesitate to choose horizontal electrical scanning and vertical mechanical scanning. At the same time, it could also assist mechanical scanning in the horizontal direction. In this way, Later, the scanning ability of radar waves was brought into full play.
"Thank you for your hard work. I am not sure whether my idea can be realized. Your test is the biggest stone in my heart."
Mr. Gao is just too humble. His flat-panel slot antenna, at least when used on airplanes, leaves all other current antenna forms far behind.
In fact, it's not just on airplanes. In Gao Zhendong's previous life, it was not uncommon for ship radars to use flat-panel gaps.
"Mr. Gao, if you are right, we will be ashamed of ourselves." Mr. Liu said with a smile.
Gao Zhendong shook his hand cheerfully: "Yeah, I won't say it any more, haha. Are you entering into the detailed design now?"
Basically, Gao Zhendong has gathered all the necessary peripheral technical conditions. It seems that the radar has now entered the detailed design stage.
"Well, yes, now we have asked the committee to completely terminate the imitation work of the RP-1 radar, and all the technical personnel have devoted themselves to this new pulse Doppler radar."
This is good news. In order to protect the PD radar, the National Defense Work Committee retained the imitation and improvement work of the RP-1 radar.
But now as Gao Zhendong comes up with radar technologies one after another, the imitation improvement of RP-1 has completely lost its meaning. It has no effect except a waste of resources and funds.
Let's put it this way, even if the PD radar is not completed, if Gao Zhendong uses these technologies and quickly builds a moving target indicating monopulse radar with an inverted antenna, he can press the RP-1 on the ground and rub it at will.
Therefore, after receiving the application from Mr. Liu and others, the National Defense Working Committee followed suit and decisively terminated the imitation of the RP-1 radar. Now they really don't like this crap.
For the National Defense Working Committee, there are many issues of dismounting midway, but this kind of dismounting is the happiest thing for them. They can do it happily and without any burden.
Gao Zhendong was also happy to hear this: "Which category are you going to do now?"
"After weighing the pros, cons and difficulties of the various PD radars you introduced, we chose the medium-heavy frequency PD radar first, which has a better balance of effect, cost, and difficulty." With the technology in hand and confidence in his mind, Liu In general, their choices have become more rational. According to their previous habits, they may want to engage in high repetition frequency PD as soon as they come up.
Gao Zhendong nodded: "Well, this is a good choice and very sensible."
Mr. Liu smiled: "The main reason is that we have evaluated that even with medium and heavy frequency, the performance after it is built can be outstanding, so we will make one with low difficulty but absolutely strong performance first, and leave better ones later, hahaha .”
Gao Zhendong also smiled: "Well, that's a good idea. Let's first decide if it's OK or not. And even if it's 'yes', it's far better than others' best."
Hearing Gao Zhendong say this, Mr. Liu felt a little embarrassed.
"Mr. Gao, we came here this time because we encountered some problems in the design. We thought about it and couldn't solve it, so we have to trouble you again."
"Well, let's talk about it and let's discuss it together." Gao Zhendong said very modestly, but for him, Mr. Liu and his team have solid basic skills. The benefit of this is that in addition to things like traveling wave tubes and flat-plate slot antennas, Except for devices like this, he only needs to provide principle solutions to most problems, and Mr. Liu and the others will solve the rest very well.
For example, anyone who is engaged in signal processing cannot do Fourier transform, and Mr. Liu and the others can do it, but Mr. Liu and the others don’t quite understand how to use the Fourier transform to solve specific problems. .
So for Gao Zhendong, as long as Mr. Liu can raise the problem, he can always find at least a principled solution. The rest will be much easier for Mr. Liu and the others, after all, they still have some Another powerful tool is digital signal processing devices, regardless of whether they are board-level or IC-level. In short, there are two worlds whether they have them or not.
"The thing is, in order to increase the transmission power, we increase the pulse width of the pulse signal."
For the transmission power, it depends on the product of the pulse amplitude and the pulse width, but the improvement is limited, even with a traveling wave tube. At this time, the simplest way is to increase the pulse width.
Gao Zhendong probably knew what was going on. Before Mr. Liu could continue, he smiled and said: "After the pulse width was increased, did you find that the accuracy dropped?"
Mr. Liu slapped his thigh: "Yes! Mr. Gao is indeed very proficient in signals. As the pulse width becomes wider, the position information represented by the echo becomes blurred, resulting in an error range ranging from a few hundred meters to kilometers. , in short, it is impossible to accurately extract the location information of the target. We have tried many methods, but this is a principle-level problem and we have not found a solution.”
In principle, the problems caused are quite troublesome, commonly known as "fetal disease". Everyone knows how troublesome congenital diseases can be.
What surprised Mr. Liu and others was that Gao Zhendong basically didn't think twice about this issue. After all, he had really looked at radar signal processing in his previous life and didn't need to search for information.
"This is simple. I'll teach you a method, pulse compression!"
"Pulse compression?" This is a brand new technology that Mr. Liu and others have never heard of.
"Yes, pulse compression, compressing the pulse width of the received signal, for example, compressing the pulse width of 10 seconds to 1 second, while keeping the peak center of the signal unchanged, can solve your problem, and it can also bring other ”
This technology was basically standard on later PD radars, and was developed to solve this problem. As for the 10 seconds and 1 second here, it was just Gao Zhendong's casual example.
Mr. Liu's familiarity with signal processing is also very profound. After thinking about it in his head, he immediately realized the benefits of this thing.
"Yes! Mr. Gao, your idea is really genius. Use a large pulse width to transmit to ensure power. Under the premise of ensuring the peak center of the signal, compressing the pulse width of the echo signal can ensure the accuracy of the target position! Absolute! Really Absolutely amazing!”
Mr. Liu's words are not flattery. He really thinks that Gao Zhendong's idea is absolutely brilliant, taking into account the issues of power (detection distance) and accuracy very well.
This thing can even be used to improve monopulse radar. After all, as long as pulses are used, this problem will exist, and this solution can solve all similar problems very well.
Although this radar is pulse Doppler, monopulse radar is still widely used on missiles. After all, it is cheap.
Gao Zhendong smiled and said: "And it can also bring other benefits."
"President Gao, don't say anything yet. Let me think about it. Come on, let's all think about it together." Mr. Liu quickly stopped Gao Zhendong, not wanting to miss this opportunity to train troops.
There are not many opportunities for top bosses to lead training troops.
(End of chapter)