Chapter 549 Let’s copy the homework together
To be honest, it is very problematic for MTI to reliably guide missiles to strike targets such as fighter jets, because the grasp of the target’s flight status is extremely vague or even non-existent. It is quite difficult to guide missiles.
The effect is probably equivalent to knowing that there is someone in a certain room, but it is completely unclear whether the person is sitting, lying, walking, male or female, old or young.
But as an early warning aircraft, knowing that there is a high-speed moving target at a certain distance and in a certain direction is actually enough, because what it wants to guide is not brainless things like missiles, but sitting A fighter jet with a pilot!
Call the fighter over and take a look. As long as a certain data refresh rate can be guaranteed, the command effect can be basically guaranteed.
And with respect to this effect, the comrades who worked on the radar were completely helpless before.
To be honest, if this technology had been available, the P-2V would have been defeated long ago, and there would be no need to wait for the Tu-4 to appear.
"Chief Engineer Gao, this effect is very good. As long as this effect can be achieved, then our fighter jets at various frontline airports will have greater use. It can be said that the low-altitude blind zone of ground-based radar And the problem of ground clutter has been solved to a great extent."
Another comrade working on radar also smiled and said: "Mr. Gao, you may be standing high and seeing far, and think this way. It’s not perfect, but at this stage, it’s enough for us.”
Gao Zhendong also realized that he was still carving a boat to ask for a sword, and he was carving a boat for decades to come. The sword in front of me is really too abstract.
He smiled and said: "Well, to be honest, I am not a professional in radar. I can only provide so much. The rest may be up to my comrades to find a solution."
"Mr. Gao, don't say that. You are more professional than us in radar. Especially your expertise is in principles and general directions. This is the only way to solve major problems."
"Don't worry, what we lack is this kind of theoretical guidance that can hit the nail on the head and clear up the clouds. We can always find a way to realize it, at least part of it."
Mr. Gao Worker, it’s boring to be too modest. If you say that again, there will be no place for us people to save our face.
Then Gao Zhendong proved with actual actions that he was really being humble just now, at least in their eyes.
"But although I can't help you much, if you don't have any ideas for phase identification and frequency identification right now, I can be of some help."
When I said these words, I was immediately reminded. Several comrades on radar seem to have never been exposed to phase detectors or other things, or have not studied them in depth. They can just copy what has gone wrong, but they are really unable to come up with a new and targeted thing.
"Ah? Have you done some research on this? That's great, Mr. Gao. I hope you will give me some advice in this regard."
When it comes to this, Gao Zhendong is not sleepy anymore , this was the content of his major in his previous life. Although he studied automation, he had a very deep communication background and spent a lot of time dealing with signals.
“There is a kind of circuit called an analog multiplier. Have you ever been exposed to it? If so, then this kind of circuit can be used for this matter. If not, let’s communicate now. ”
Gao Zhendong didn't know how well they mastered the analog multiplier, an important circuit used for signal simulation processing, but he estimated that the situation might not be optimistic, otherwise he would not have seen the first-generation early warning aircraft that had been in use for so many years facing him in his previous life. Unable to solve the clutter problem, I sadly gave up.
In short, everything is lacking in technology in this era, and it is not surprising that this is lacking.
Analog multiplier, a circuit composed of amplifier devices such as transistors, can directly complete the multiplication of two analog quantities. The two analog quantities may be voltages or currents.
In the signal processing process, processes such as amplitude modulation, detection, mixing, frequency multiplication, frequency identification, and phase identification are actually processes in which two signals are multiplied or contain multiplication operations.
The analog multiplier Gao Zhendong used in his previous life is already an integrated circuit device, but this does not mean that it cannot be built with triodes. Before this circuit was integrated, it was originally built with triodes. During experiments and projects, Gao Zhendong did it himself.
"Multiplier? Mr. Gao, I have read the latest computer textbooks. Even computers now only have adders. Multiplication is achieved through addition, and it is a digital circuit. Isn't this different from the signal type we have now? ? And digitizing radar signals is a troublesome thing. "
This is the current technical environment. Everything is lacking and everything is relatively rudimentary. The entire process of radar signal processing is basically complete. It's analog, but the multiplier Gao Zhendong proposed to them happens to be analog, and it just fits the current conditions.
What this comrade said is probably the content of the general computer architecture that Gao Zhendong himself came up with. Not to mention, they are really far from lagging behind in learning. It’s just the content of this book and What Gao Zhendong is talking about is two different things.
As for digital hardware multipliers, they will actually exist in the future, but they are rare in general-purpose computers. In another device, it is the core.
Hearing this, Gao Zhendong smiled and said: "Well, it doesn't matter. This multiplier circuit is originally used to process analog signals, and can save the process of digital-to-analog conversion."
Gao Zhendong didn't say a word - guess why I specifically mentioned this to you?
Several comrades looked surprised, there is such a good thing? Gao Zhendong first introduced the general situation and uses of analog multipliers. After listening to Gao Zhendong’s introduction, a group of comrades exclaimed that they had found a treasure.
This thing is not only used in this one place, with current radar and signal processing, it can be used in many places.
A group of people stared at Gao Zhendong with twinkling eyes - where is the picture? There should be a picture here!
As a mature instructor, Gao Zhendong has long since learned to draw pictures by himself. He took out a pen and paper and started drawing directly.
The circuit schematic diagram of the analog multiplier is not too complicated, but it is not simple either. It took Gao Zhendong some time to draw it.
A group of comrades working on radar copied it first without saying anything!
Although they are all engaged in radar, they are outstanding leaders from different units. Otherwise, they would not be invited to this seminar. Since they are from different units, Gao Zhendong’s paper does not belong to anyone. It’s convenient for you to take it away, no one else will let you, so just copy it!
"Don't block it, don't block it..."
"Til your head, it's blocking the picture..."
"Don't pull at me, I can't see clearly if you're far away..."
Gao Zhendong poured a glass of water and looked at it happily The comrades copied the work meticulously. On this kind of schematic diagram, the resistance, capacitance, sensor and other components are basically not marked with size, and the drawings are relatively casual. If you are not careful, you may make mistakes in copying.
In his previous life, any of these people in front of him would have been someone he would look up to. Now that he is seeing their heads gathered together in a pile to copy his homework, Gao Zhendong feels really good in his heart. .
When the copy was almost complete, a comrade exclaimed: "Ah, I seem to have seen a similar circuit to this. In Lao Maozi's radar, in a large area of circuits, similar circuits should be distinguished. Come in a small piece, but we don’t know what this thing is for, and we can’t even distinguish its boundaries.”
It should be said that this comrade is also very remarkable, and he is able to understand the entire radar back-end processing circuit by heart.
Another comrade was also in a very good mood and joked: "I knew it before, let alone the changes. I didn't even know what this place was for. Now I know why and can It’s really used.”
The difference between imitation and development is here. You can just copy it without knowing the reason. Anyway, you can get the result in the end. But if you want to improve, it is very difficult. Development is another story.
Facing the circuit diagram, Gao Zhendong explained the principle of the circuit, component selection, functions of each component, etc. to the comrades one by one. While listening, several comrades were full of praise, "Good, wonderful, High-level words are endless.
When Gao Zhendong finished speaking, several comrades looked at each other and solemnly said to Gao Zhendong: "Thank you, Chief Engineer Gao!"
Gao Zhendong shook his head: "I should thank you." Only he understood what he meant.
Several comrades reviewed the full set of gains just now. Gao Zhendong has taught everything he can from the ideas, principles, system composition, and core components. If he can't change it himself, how can he achieve it? It's too outrageous to move the thing indicated by the target.
Some comrades have already begun to consider how to implement this problem in their heads.
One person who thought faster suddenly reacted: "Hey, this circuit can also double the frequency?"
Radar signals require a high-precision signal source, which is electromagnetic waves. The frequency cannot float around, and parameters such as duty cycle must be well controlled, otherwise it will become inaccurate, and the subsequent ones will also deviate, or even deteriorate to the point of being unusable.
To give a similar example, the reason why the travel time accuracy of an electronic watch worth a few yuan can surpass all mechanical watches, no matter how high or low, is that its crystal oscillator has high frequency and good stability. No matter how precise the mechanical watch is, the swing frequency can reach 5Hz is considered high, 8Hz is top-notch, and electronic watches that cost a few dollars basically start at 32kHz. That's it, and the stability issue has not been considered, otherwise mechanical watches will be even more shameless.
As for high-precision signal sources, before electromagnetic waves can be amplified, they must first have an oscillation device with good enough precision and high enough frequency.
High-frequency signals are generally obtained by multiplying the frequency of low-frequency signals. This thing seems simple in later generations. The frequency is just a few G and it is very cheap. But for us now, it is still not simple.
(End of this chapter)