Chapter 738 In fact, good things are not necessarily expensive
They quickly stood up and began to draw the radar plan on the blackboard.
They didn't want to erase the coordinate map drawn by Gao Zhendong, as they might be able to use it later, so they just drew it in the corners and explained it to Gao Zhendong while drawing.
Gao Zhendong generally understood. This radar was born out of the Zhengxian No. 1 radar. The principles are similar, but the digital signal processing board and DJS-60DJ are used to enhance the radar signal processing capabilities, and according to Gao Zhendong's guidance, dynamic The target indication function enhances the ability to resist clutter.
The plan is very satisfactory, with no major flaws, but also no major features. It can be regarded as using advanced technology to solve the inherent problem of small caliber. However, judging from the results, the solution is not complete, mainly because it cannot adapt to the further reduction of sea skimming flight altitude. .
Gao Zhendong looked at their plan and asked: "Can you see the capture status of the target from the radar data?"
Qi Gong thought for a while and said: "I can tell a little bit. The amount of radar data is relatively large. It is impossible to record the original signal. Only some resultant process data and important nodes will be recorded."
< br>
Gao Zhendong said: "Look at the radar data first. How well is it locked on the target?"
The roughly translated meaning is whether the target echo is clear and whether the target status and position are accurate.
Qi Gong nodded: "This can be seen a little bit. When locked, the situation at the time of locking will be recorded."
After saying that, he and Su Weihua began to look through the data records to find the answer Gao Zhendong wanted.
After they found it, they took a few glances and raised their heads, full of admiration.
"Professor Gao, you have known for a long time that radar locking is unstable? The error range for judging the target position is relatively large?"
Gao Zhendong nodded: "My guess is that your radar has limited power. If you want to enhance the energy of the radar signal and improve the signal-to-noise ratio, the only way is to increase the pulse width."
This radar is a monopulse radar, which is cheap and plentiful. It is suitable in terms of type for use on this missile. The price of PD is very high.
The total energy of the pulse signal is related to the amplitude and pulse width. When the power is limited, it can only be improved by increasing the pulse width.
The reason is known, but the principle is not known. Su Weihua said: "Lao Gao, why does increasing the pulse width reduce the positioning accuracy?"
"Because the pulse width is larger, it means that the time range of the radar echo signal is longer. Naturally, the calculation is inaccurate and can only calculate a very large range."
Even the initial locking is relatively vague. When the clutter worsens, the possibility of natural unlocking increases.
If you find a problem, you will at least have a direction to tackle it. Even if Gao Zhendong doesn't say the solution, it will still be helpful to Qi Gong and others, but things are far from that simple.
"Now that you have used the digital signal processing board, you have the basic conditions to solve this problem. Let me give you a suggestion. You go to XX unit and communicate with them about pulse compression technology. Regarding your problem, It's helpful." Gao Zhendong pointed out a way for them directly.
Gao Zhendong gave them a brief introduction to the benefits of pulse compression technology, which made Qi Gong extremely excited. Every benefit of this technology is based on our needs, including improving accuracy, resolution, and signal-to-noise. I want it more than...!
"Ah? Some units are already working on related technologies? But can we get them if we go there?" Qi Gong was both happy and worried, asking for technology in vain, how can it be so simple?
Gao Zhendong nodded: "I will write you a note. You can just go to the National Defense Work Committee and ask for permission. There should be no problem." This kind of basic technology will naturally be spread as widely as possible among relevant domestic units. Everyone will Use it.
When Mr. Li and the others heard his words, they naturally understood that this pulse compression was absolutely inseparable from the person in front of them. Even judging from his confidence, the role he played in it was very important. .
Su Weihua even had the feeling that he had gone to college in vain. Did Gao Zhendong secretly study while they were sleeping every day? It's not on the same level at all.
He fell into deep self-doubt, but for Qi Gong, it was good news from heaven. In one word, it was great! ! ! !
Gao Zhendong didn't care how happy he was. In Gao Zhendong's opinion, this radar system had more than one problem, or there were areas that could be improved.
He pointed to the schematic diagram of the radar structure on the blackboard: "This antenna of yours uses an upright long-focus parabolic antenna?"
Parabolic antennas are suitable to be used here. At this time, we are not in the future when phased array radars are flying all over the sky and pesticides are sprayed on the phased array.
Qi Gong nodded: "Yes, the cost of the parabolic antenna is appropriate, and the directivity and side lobe performance are good. Overall, it is more suitable than Cassegrain and reverse card. The long-focus parabolic antenna has better electrical performance than the short-focus paraboloid." Some finally adopted this plan.”
Both Cassegrain and reverse jamming will cause side lobes to rise and gain to drop due to the shielding problem of the sub-reflective surface. This is a problem for solid anti-ship missiles that have limited total energy and have to fight against severe sea clutter. , much worse than the parabolic antenna. Another reason is that the radar of Zhengxian No. 1 is an upright long-focus parabolic antenna.
Gao Zhendong also recognized his overall choice, but he had some suggestions on specific plans.
"Well, it is indeed good to use paraboloids here, but as for the specific plan of the parabolic antenna, I have a suggestion to use a telephoto offset parabolic antenna instead."
"Offset paraboloid?" Qi Gong was not one of the top radars, so he didn't know much about this thing.
Gao Zhendong nodded and explained to him the offset paraboloid. It is actually very simple. The upright paraboloid places the feed at the center focus in front of the paraboloid. The offset paraboloid intercepts a part of the parabolic antenna and the feed remains the same. Place it at the focus of the complete paraboloid to which that part belongs, so that the feed appears to be on one side of the antenna without central occlusion.
Gao Zhendong drew a rough diagram, and after looking at it together, they intuitively felt that this method was interesting and wonderful!
"Professor Gao, your method is great. It seems that a simple deflection solves the problem of the signal field being blocked by the feed and the feed bracket, reduces the side lobe level, and improves the signal gain."
This is a typical example of conflict between theory and practice. In theory, the performance of an upright feed is the best, but in fact, due to the occlusion of the feed itself and the bracket, it will have a considerable impact on the radar signal.
Because the source of reality is not a point during theoretical analysis, but a real entity. As for the bracket, there is no such thing at the time of analysis, but in fact it cannot be dispensed with.
This is just like the "particle" in mechanical analysis does not exist in reality.
Gao Zhendong smiled and said: "You have to pay attention to this. The maximum receiving direction of the feed must be pointed at the center of the offset reflector. In this way, basically all the advantages are obtained, and the disadvantages are not increased."
For Gao Zhendong, Qi Gong and Su Weihua were all in admiration. This is a simple offset. It seems simple, but the most essential part of it is "intercepting a part of the paraboloid and using its original focus to achieve the offset effect". They are not You can imagine.
"Thank you so much, Professor Gao, you really have nothing to say about your skills." Qi Gong is more confident in solving the radar problem. With better antennas and better signal processing technology, he I don’t believe this problem can’t be solved!
Gao Zhendong added: "You guys try this antenna first. If it still doesn't work, we will think of another way. This way is the cheapest."
What? What else can you do? Just because this is the cheapest, why should we try this first?
Qi Gong suddenly remembered a common character in martial arts novels - Bai Xiaosheng.
Gao Zhendong really has a way. The antenna can actually be a flat-panel slot antenna. The performance of that one is better than these, but the only problem is that it is expensive!
Gao Zhendong has no idea of putting all new technologies on the market. The most important thing for tactical missiles such as anti-ship missiles is that they are sufficient and usable, and they must be cheap and simple enough to facilitate mass production.
The problem of dropped bombs is basically clear. At least in the eyes of Mr. Li and others, there is currently no other evidence to support other problems. They are extremely satisfied with the results of this visit to Beijing. Professor Gao is reliable!
Seeing this, Mr. Li also asked something else: "Professor Gao, do you have any other suggestions for this missile?"
Gao Zhendong thought for a while and made a suggestion that was not a suggestion.
"You all know about C6108, right?"
"I know, I know." They all knew very well about this thing. It was another proud work of the person in front of them.
"I suggest you replace the DJS-60DJ with a C6108-based computer. In fact, the C6108 system is much cheaper than the DJS-60DJ, and it can save a lot of volume and weight. The C6108 can be specially selected for military reinforcement. version.”
The DJS-60D itself is not too heavy, but after being reinforced by the military, the weight suddenly went up, weighing dozens of kilograms. The motherboard area is only about one-eighth of that of the C6108. Counting the reinforcement, In terms of cost and weight savings, it's really a world of difference.
Li and Qi were both surprised and happy about the news.
They don't want to use C6108? I can only dream of it. It is lighter and smaller, and the computing speed is at least 2.5 times higher. I would be a fool not to use it.
But I can’t afford it. Such a good thing must be expensive, right?
I didn’t expect to be here with Gao Zhendong and learn that this thing is actually cheaper than DJS-60DJ? Why don't you fuck me hard?
"Is this true? Thank you so much, Professor Gao." Mr. Li thanked him repeatedly. The guidance subsystem of Qigong is not the only one that can benefit from this thing.
(End of chapter)