The Military-industrial Scientific Research System of the Academic Master Chapter 263

Chapter 263 Adults choose everything (two in one)

 For the engineers of Institute 14, the current situation is generally a mixed blessing.

 The success of Pod No. 1 can be regarded as a guarantee, at least it allows everyone to confirm that they are going in the right direction.

 So now the No. 2 pod faces at most an engineering design problem, and it may even be a minor problem with the manufacturing or assembly process.

 This will have to wait until the test data and the radar data from the anti-aircraft artillery regiment are returned before slowly checking it.

However, for Chang Haonan, achieving this step is obviously not enough.

When he first arrived at the 14th Institute, he used the system to analyze the working principle of the captured pod, so this step was definitely not wrong, and it was the scaled-down version of the No. 2 pod that truly represented his own work.

 So no matter what, he still hopes to solve the problem quickly.

 About 20 minutes later, aircraft No. 713, which had completed the test, landed steadily on the runway of Yanliang Airport.

Soon, the two pods, one large and one small, were dismantled by the ground crew and moved to a workshop specially arranged for No. 14 for testing.

 Subsequently, Guo Lin and others began to disassemble the pod and check whether there were any problems with the component installation, while Chang Haonan and Xu Yang removed the test equipment on the aircraft.

 It can faithfully record the working conditions of various airborne equipment during the entire flight just now.

 In the first two rounds of tests, that is, when the No. 1 pod was activated for interference, everything was normal throughout the process.

 But when the No. 2 pod was opened, the situation became very strange.

At the beginning, that is, when the pod has not captured the radar waves directed at itself, the data is still normal.

 This shows that there is no problem in the power-on step.

 However, when the aircraft entered the detection range of the artillery sighting radar and the jamming pod actually entered working status, an abnormality occurred at the signal receiving end.

 This is true for both the third and fourth rounds of testing.

And as the distance to the radar body approaches, or as the energy emitted by the jammer increases, the signals recorded by the pod's receiving end become increasingly chaotic.

 “Chang Bo.”

Just as Chang Haonan frowned and stared at the signal map on the screen, Xu Yang's voice suddenly sounded from behind him:

“Enlarge the signal of the last minute of the receiver and take a look.”

Chang Haonan's content about signals and control was actually slowly taught by himself after he was reborn.

Of course, thanks to the knowledge the system has given him in several related projects, he is able to handle general application problems with ease.

 However, compared with people like Xu Yang who have a professional background, they are still slightly lacking in basic skills training.

Just like now, Chang Haonan may not be able to react faster when he needs to find the real problematic part from a bunch of complicated lines.

But one advantage he has is that he can listen to what others say.

 So I immediately followed Xu Yang's request to enlarge and process the last minute records of the last two rounds of testing.

"look here."

Xu Yang pointed at one of the curves:

“The amplitude of this curve is very low at the beginning and is almost invisible, but it will increase every cycle from its appearance, and in the end it will even be about the same intensity as the gun sight radar wave received by the receiver.”

As soon as she said it in such a concise manner, Chang Haonan immediately grasped the key point:

“So it interferes with the input signal of the entire pod, causing the output signal to be abnormal, and the interference effect on the radar becomes worse..."

“Wait, this is a self-oscillating signal?”

 “That's right.”

Xu Yang snapped his fingers:

“So the situation is very clear. The problem is not with the components. We can stop Guo Gong and others from continuing to investigate.”

Chang Haonan slapped his forehead with some annoyance, and then called Guo Lin and others who were busy analyzing the circuit board on the other side.

 If it is just a simple interference signal, then there are actually countless possible sources.

For example, some part of the process in DRFM is not good, or there is a problem with the sampling clock of a certain channel during the frequency division multi-channel sampling process, etc.

But none of these problems can create a positive feedback self-oscillation signal.

The only possibility is that the isolation between the pod's transmitting and receiving antennas is not high enough, and the high-power interference signal emitted by the transmitter is coupled from the receiving antenna into the receiver.

The people at the 14th Institute also have a professional background. Although if they were asked to find the problem on their own, they would not be able to see it at a glance like Xu Yang, but it is definitely not difficult to understand Chang Haonan's meaning when there is an explanation.

 “So that's what it is…”

Guo Lin also smoothed his hair in surprise:

“But we have obviously implemented polarization isolation?”

The so-called polarization isolation means that the transmitting and receiving antennas are arranged in an orthogonal manner, with one vertically polarized and the other horizontally polarized. Theoretically, there will be no crosstalk between the signals between the two antennas.

However, because it is impossible to achieve truly perfect orthogonal polarization when implemented in engineering, it will still be affected to some extent.

“This shows that our polarization isolation is not high enough. When the distance between the carrier aircraft and the radar antenna approaches a certain level, the power of the transmitter will burn through the polarization isolation, affecting the normal operation of the receiving antenna.”

Haonan put down the mouse in his hand, looked at the No. 1 pod not far away and replied:

“And I also understand why Raytheon designed the pod to be such a large size…”

"really…"

　　 Xu Yang, who was the first to raise this question and has been troubled by it, also showed a look of understanding:

“They couldn't solve the problem of polarization isolation, so they used the simplest and crudest physical isolation method. As long as the distance between my transmitting and receiving antennas is far enough, I won't be afraid of being affected.”

 Now that the problem has been clarified, the next step is to find a solution.

 In fact, the idea is quite logical.

 After all, there are actually only three commonly used sending and receiving isolation methods.

 Spatial isolation, polarization isolation and time isolation.

The first type is physically impossible due to the size limit of the pod, and the second type cannot be realized due to technical problems. Naturally, the third type is left.

So Guo Lin expressed his thoughts:

“What if the all-receiver-all-transmit mode is abandoned and the time-sharing working logic of transmitting and receiving is adopted, such as full-pulse store-and-forward interference, or short-pulse store-and-forward interference?”

Xu Yang had naturally thought about this, but she still shook her head resolutely: "Then the advantage of our jammer is gone. The short-pulse storage and forwarding jamming only uses a short section of the radar signal to cycle end-to-end. If forwarded, the false target signal generated will become very wide, and a slightly more advanced radar can easily distinguish true and false targets. "

"As for full-pulse store-and-forward jamming, although the target generated is very real, the false target will lag at least one pulse width behind the real target echo. It is okay to deal with some airborne narrow-width radars, but if it is against something like the Patriot, For linear frequency modulation pulse compression radar, if others directly use a width of 60 microseconds or even 100 microseconds, then our false target will be directly behind the real target by 10-15 kilometers, and it will not be able to confuse the enemy at all. "

 After Xu Yang blocked the last way out, Guo Lin really couldn't think of any other way.

“MD, it makes sense for Americans to build such a big thing...it's so difficult...”

Guo Lin patted the huge pod No. 1 next to him.

This guy, which is nearly 10 meters long and about 1 meter in diameter, is a behemoth that cannot be carried by most tactical aircraft.

 In addition to the MiG 25/31, it is really difficult to find a suitable tactical platform as a carrier for it.

 The largest equipment mounted on the Su-30 in the previous generation was the BrahMos with a length of 8.4 meters and a diameter of 670mm. The record for the Su-34 is the Kh-47M2 Dagger, which is 7.5 meters long and has a diameter of 1.2 meters.

  In other words, only Su 34 can barely hang up.

But let's not say that China does not have a model corresponding to the Su-34. Even if it does, the sealing of the belly mounting point is too high. The front is blocked by the classic drooping nose of the Flanker family, and the two sides are blocked by two incoming air intakes. The airway is blocked and is not suitable for placing interference pods that require a large amount of receiving and transmitting electromagnetic waves.

 “How about we change our thinking?”

 After a few minutes of silence, someone next to me finally suggested:

“Perhaps there is no need to design this thing as a pod.”

"I heard that the institute's research progress on the active and passive SAR radar is also pretty good. Can we consider combining the electronic jamming and electronic reconnaissance functions into one, integrating them into the Y-8 or H-6, and building one directly? When the integrated electronic support aircraft comes out, the Air Force will definitely like it."

This model is very close in concept to the later Gaoxin 12/Yun 9DZ electronic warfare aircraft. As he said, the Air Force really likes it.

Although it is difficult for this kind of aircraft to follow the formation of tactical aircraft to fight together and destroy the opponent's air defense network with physical means like the EA6B or EA18G, it can at least provide cover in a relatively safe place. It is better than simply relying on low-altitude penetration to try your luck.

Moreover, in non-wartime patrols and confrontations, larger platforms are more capable than Flying Leopards or Flankers.

In the previous life, the Chinese Navy and Air Force made very good use of the long airtime advantage of the high-tech series aircraft (the range of the Y8/9 platform is actually not far, but the economic speed is relatively low), and responded by repeatedly allowing the Air Self-Defense Force to take off at super intensity. This method has greatly weakened the combat readiness level of the opponent's main fighters such as F15J/DJ.

 So that some time before Chang Haonan was reborn, Air Force was already considering using the F2, which was originally designed for ground-to-sea attacks, to conduct air interception missions.

　　That seems to be a good result.

 Especially now that China urgently needs to deploy naval and air forces in certain directions to declare its presence.

But just when some people were moved by this idea, Chang Haonan, who had been turning his back to everyone and calculating something on the computer, suddenly turned around:

“Of course we need to develop integrated electronic support aircraft.”

“But tactical electronic warfare attack aircraft cannot be just abandoned.”

 Children only make choices, adults only say I want them all.

“But Chang Gong, the self-interference problem after the pod size is reduced is difficult to deal with..."

 Someone whispered.

 In fact, Chang Haonan just perfected the inspiration that flashed through his mind on the computer, and then used the system to test whether it could form a closed loop.

The fact that he has not received systematic professional training is his disadvantage, but it is also his advantage.

 Compared to Guo Lin and others, Chang Haonan's thinking set is obviously much less.

 The final answers are all feasible.

 It's just that this time he did not continue to build a new project through the system. Instead, he decisively chose the glorious free prostitution after confirming that the idea was okay.

If possible, Chang Haonan still hopes that this matter can be completed by "himself" in the true sense.

 It's not just for the challenge, but also to exercise your own abilities, especially theoretical experience.

He discovered a long time ago that when completing tasks of similar difficulty, the scientific research points obtained without using the system are not much different than using the system, but the ability value and experience obtained are completely different.

This is easy to explain. After all, the knowledge I have gained bit by bit must be more solid than the knowledge gained directly from the system.

 After his rebirth, his engineering experience and management abilities have made great progress, but although the [theoretical level] has also gained some experience points, it still remains at the LV2 level.

Of course, there is the factor that upgrading from LV2 to LV3 requires up to 10,000 experience points, but in any case, as the level of the projects he participates in becomes higher and higher and the content becomes more and more complex, Chang Haonan has begun to feel that the theoretical level of LV2 is somewhat beyond his capabilities. .

For example, the multi-physics simulation modeling software mentioned when I chatted with Yan Zhongcheng at the Three Doors Celebration Banquet.

 He thought for a long time and started some theoretical construction in his spare time, but without exception he failed to form a complete and feasible idea.

 So it is necessary to "brush" some theoretical level experience points.

But just when Chang Haonan was about to speak, a younger engineer suddenly took over the conversation:

“Actually, I think we should consider the pod and aircraft platform as a whole.”

The former almost choked as the words were blocked in his mouth, but he still motioned for the other person to continue speaking.

"Our current idea is to hang two pods with the same function on the aircraft to superimpose the interference power. But in fact, this is not necessarily necessary. It can be done... For example, on the left side, the pod is only responsible for receiving the signal illuminated by the radar. , then processed by the aircraft's computer, and then the pod on the right is responsible for transmitting the interference signal..."

"In fact, the entire aircraft is designed as a flying pod. In this way, even an aircraft with a relatively small wingspan like the J-8C is almost 9 meters long, and there is an entire fuselage in the middle as a shielding isolation. It is completely OK. Meet the requirements for spatial isolation.”

 Hey guys, open your mind.

If the atmosphere at the scene was not quite serious, Chang Haonan would even want to applaud.

The other party's words reminded him that it was very likely that in the past, when the electronic warfare aircraft of the United States and the Soviet Union faced similar situations, they used similar ideas to avoid the self-interference problem that occurred in simultaneous transmitting and receiving jammers.

In addition to poor flexibility (an aircraft must be significantly modified, the two pods hanging on an ordinary aircraft are completely useless), this idea can only interfere with an angle of approximately 45-60° on one side of the aircraft fuselage ( The jamming signals of most jammers are effective in an arc-shaped area of ​​90-120° straight ahead), so apart from the strict requirements on heading, it is not a big problem.

 It's actually a pretty feasible solution—

If it weren't for the fact that Chang Haonan already had a better solution in his mind.

“Ahem...the problem of self-interference is indeed difficult to deal with, but it may not be insurmountable.”

 (End of this chapter)

Chapter end