264. Chapter 264 Intermittent sampling and successive loop forwarding interference


Chapter 264 Intermittent sampling and sequential loop forwarding interference

Everyone’s attention was once again attracted to Chang Haonan.

"Chang Gong, you mean..."

The engineer who just proposed to design different functions for the two pods and then divide the work and collaborate also looked over.

He really felt that his plan was quite perfect.

Although it can be regarded as opportunistic in a certain sense, it is at least opportunistic with a relatively high technical level.

"What Guo Gong mentioned just now is to let the receiving and transmitting antennas work in a time-sharing manner. I think it is feasible."

Chang Haonan's words made Xu Yang's eyes widen.

That expression basically says "I read a lot, you can't fool me."

But he continued:

"However, the two traditional methods, whether full pulse or short pulse, work based on a time width of the captured radar signal. Even the latter only uses a small section of the radar signal to perform head and tail analysis. The consecutive cyclic forwarding will not start a new receiving-calculating-sending process until the next time interval. "

"But we can use radar to transmit while keeping the overall structure of the current hardware unchanged. A signal with half the width of the pulse is used as an interference signal."

"Half width?"

This slightly surprising proposal initially caused some minor waves in the crowd.

However, someone soon realized that this approach seemed to be feasible in theory.

Especially for chirped pulse compression radars, which are increasingly common.

However, even in the United States, things like electronic warfare are still in the barbaric stage of development, but I have never heard of anyone systematically demonstrating this.

“However, if we still use the previous method of sampling first, storing the signal and then waiting for half a cycle before forwarding, then it will only change the lag distance of the false signal from 10-15km to 5-7.5km. This The distance is not deceptive to either the radar or the radar operator, and it also does not play a role in covering the real target."

The engineer from before was still speaking, and he obviously wanted to protect himself. Struggle with the plan.

"You are right, so I choose not to go through this storage process."

This statement is even more shocking, because a significant advantage of digital jammers based on DRFM compared to jammers that achieve phase modulation and frequency shifting with traveling wave tubes is the ability to store frequencies.

“Of course, strictly speaking, it does not go through a complete storage process.”

Chang Haonan revised his statement again.

Guo Lin, who was already familiar with this scene, immediately took out a pen and paper from the briefcase he carried with him and handed it over.

He knows that what he should do at this time is to watch the big man's performance and see what he can learn from it.

If you have a chance, you can be a compliment.

Chang Haonan also took it directly as a habit, and then began to draw the schematic diagram.

But this time the content is relatively simple, just a simple coordinate axis.

“My idea is that after the receiver intercepts a large time-width radar signal, it only samples a small section of the signal with high fidelity and processes it immediately, and then forwards it by the transmitter, and then performs the second Segment sampling is processed and forwarded to the next segment, and this cycle is repeated. The sampling and forwarding work alternately in time until the end of the large time-width signal. "

"The receiver and transmitter of the jammer work in time-sharing throughout the pulse width. Time isolation can be achieved perfectly, and since each sampling time and forwarding time are the same, exactly half of the radar emission pulse can be captured, achieving the half-width signal interference I just mentioned.”

This is the benefit of not having a fixed mindset.

Compared with the sampling half-cycle-forwarding half-cycle model, Chang Haonan’s proposal actually only shortens the cycle of this process, but the effect of generating false targets is vastly different from the former. .

Not to mention operating in full cycle units.

But of course this little cleverness is not all. The real core technology lies behind:

"In addition, the processing algorithm here cannot continue to use simple direct forwarding methods, which will only generate a main and false target that is exactly the same as the real target and 2-3 realistic fake targets that have the value of confusing. The rest is It has no practical value."

"But if we use repeated forwarding or circular forwarding on the interference algorithm..."

"..." (You will not be interested in these two algorithms. Interested)

"In this way, a large number of realistic false targets with strong amplitude can be generated within 2-10 microseconds before and after the real target. This form is very suitable for accompanying electronic warfare aircraft to accompany the team. Jamming or self-defense jamming by tactical aircraft, the specific false target generation characteristics can also be adjusted by changing the processing parameters in the pod control software to adapt to different combat environments.”

Chang Haonan already has a little bit in his hands. He put down his dull pencil and looked up at everyone.

"Well... in this case, we need to replace it with a new FPGA, but other than that... it seems that everything can be done based on the original circuit."

After hearing this "intermittent sampling successive loop forwarding" After thinking about "interference", Xu Yang almost immediately thought of the key points for improvement.

“In addition, it is best to modify the antenna structure and replace it with an Archimedean spiral antenna. The two arms are fed with equal amplitude and anti-phase. This way, bidirectional circularly polarized radiation can be obtained in a wide frequency band, and the broadband The input impedance of the antenna remains unchanged within the band range."

Chang Haonan continued to add.

“I understand.”

Guo Lin next to him had already written down several pages of notebooks. Although his reaction was slower than that of Xu Yang, he was still an engineer with formal training and had already begun to think about how to minimize the impact on the engineering design of the pod. Modifications were made to complete this prototype upgrade:

“The replacement of the antenna and FPGA is not complicated in operation. I can even do it manually. I can send these requirements back to Jinling and let them send the corresponding The components are built and delivered, and we replace them on site. As for the intervening days, we can focus on testing the No. 1 pod.”

What Guo Lin proposed is basically the most compact plan in terms of time.

There is no way, time waits for no one, and machine No. 713 was borrowed from the 38th Institute after all, so it is not easy to keep it and not return it to others, so every day is faster.

Everyone quickly reached a consensus and continued the experiment according to the above plan.

The No. 1 pod is not without value. Although the algorithm proposed by Chang Haonan is very clever, in the end it is still a compromise. If we really want to talk about actual performance, it cannot be achieved when the component specifications are consistent. It is comparable to the former which achieves transmission and reception isolation by increasing the spatial distance and can work in all-receiver and all-transmit mode.

Sometimes, big is really good.

So on the integrated electronic warfare aircraft of the Y-8 platform where space is not tight, there is no need to use the intermittent sampling scheme.

"In addition, I went to the 172 Factory last night to take a look. They happened to have a JH-7 that was about to complete its mid-life upgrade. After our No. 2 pod was tested on the No. 713 aircraft, It can be directly installed on the Feibao platform to see the actual effects of the team interference mode and the self-defense interference mode respectively. "

After all, it is really outrageous to rely on a Y-7 simulated attack aircraft.

After the solution was come up, the atmosphere in the entire conference room was no longer as heavy as it was at the beginning.

“If I want to use the JH-7 for testing again, I feel like I have to find another brother unit to cooperate.”

An engineer said in a joking tone:

“I just said I heard from people at the Flight Test Institute who went to the 139th Division Anti-aircraft Artillery Regiment for testing that their regimental commander was hit hard after the first two rounds of tests. It wasn’t until the second half of the test that our No. 2 pod was not effective enough that it eased a little. Come here."

There was a burst of cheerful laughter.

"You really can't take advantage of the big brother of the army."

Chang Haonan also smiled and waved his hand:

"And this time we are in a hurry for testing and can't contact other troops. Artillery Aiming at the radar is not a particularly good imaginary target. Next time we try to find an air defense missile regiment of the Air Force to try the effect!” Counting 1 character, there is actually no way to count the number of characters). The main reason is that after the revision, Qidian cannot recognize some special symbols and Greek letters, resulting in all the garbled codes and question marks being sent out...

 

(End of this chapter)

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