The military-industrial scientific research system of the academic master.

Chapter 1195 Deployment location at sea?

Li Jianqiang's third request was finally met.

However, given Chang Haonan's current status, he certainly can't just make a phone call and call someone over.

So I still have to go back and wait for news.

Of course, Li Jianqiang had anticipated this long ago, so his plan was to first solve basic problems such as radar signal form, waveform function, and deployment location.

After obtaining external assistance, we will consider how to upgrade the software and algorithms based on the existing radar.

Therefore, as soon as he returned to the institute, he immediately gathered all his subordinates who had no urgent work to hold a meeting, explained the current basic situation, and assigned specific tasks to each of them.

However, things did not go as smoothly as expected.

Although they have conducted research in this area for several years and have obtained many meaningful results.

But when it came time to put the theory into practice, we discovered many problems that had not been considered before.

The most difficult one is that the anti-stealth principle of dual/multi-base radar is to use the scattering of electromagnetic waves, which largely exhibits irregular characteristics, and the transmitter and receiver belong to different radar terminals, so it is difficult to use traditional technologies such as cluster analysis, matched filter sampling, and narrowband automatic gain control to perform dense multi-target resolution.

In other words, within a relatively small range (tens of kilometers to hundreds of kilometers), no matter how many targets actually exist, the radar echo will treat them as the same reflected signal.

If facing a normal target, the radar operator can also make inferences based on the target signal strength.

But the F22 is a completely new opponent.

No one knows what its specific target characteristics are.

And even if we know it, the signal may be distorted after scattering, leading to errors in judgment based on experience.

This is quite fatal in a confrontation.

For four or five days, Li Jianqiang was troubled by this.

Because the problem of multi-target resolution cannot be solved, there is no way to determine the deployment location of the radar, let alone optimize the echo signal model based on the geometric relationship between the transmitting station and the receiving station...

"How about...we settle for the next best thing?"

In the smoke-filled office, Li Jianqiang's deputy Zhu Yongshun suddenly proposed.

"Tell me what you think."

The former really had no idea at the moment, so he had to answer with the mentality of trying everything possible.

"It is possible to add a second (bistatic) receiver to a monostatic radar system (a transmitter and receiver in a coordinated configuration), so that the monostatic radar system serves as the primary detection sensor and the bistatic receiver assists in the detection of targets."

Zhu Yongshun pulled out a piece of paper from the side and continued to introduce while drawing a diagram on it:

"The monostatic radar system can be used as the primary detection sensor, while the bistatic receiver assists in the detection of targets. The transmitter area of ​​interest is divided into a grid using circular range cells for the monostatic radar receiver and elliptical range cells for the bistatic radar receiver."

"Then, the signals of the two receivers are fused to establish a likelihood function. After the amplitude of the target corresponding to a certain grid that maximizes the likelihood ratio of the signals received by the two receivers is determined, this optimal value is compared with the threshold..."

This proposal was not difficult to understand, so Li Jianqiang interrupted him halfway through his speech:

"and many more……"

"According to the composite configuration method you mentioned, the entire plan will change from a complex multi-base radar network with multiple transmissions and multiple receptions to a simple dual-base radar network with multiple single transmissions and multiple receptions... This is equivalent to adding several additional restrictions to the radar deployment location out of thin air, and the calculation difficulty will increase exponentially."

Zhu Yongshun, who was pointed out the key point, showed a helpless expression and rubbed his swollen scalp:

"You are right, but other technical solutions, whether it is the use of spatial diversity characteristics or the signal level fusion of echo information... let's not talk about whether our current technical capabilities support this. Even if Academician Chang brings the solution to us, it still requires the support of the radar's own underlying architecture. It is definitely not something that can be solved by making minor repairs to the current model."

Li Jianqiang tapped his head lightly with a pen, closed his eyes and showed a tangled expression——

If we skip the current problem and only use the most basic Doppler beat frequency principle to detect the existence of the target, it will not be too difficult to implement.

But since others are doing things in the name of joint exercises, it is impossible that the only aircraft dispatched are stealth aircraft.

If a non-stealth F15 or F16 is used as bait and the F22 is placed at a certain distance for ambush, the simple multi-base radar will only detect a single and obvious echo signal, but will not be able to distinguish the details at all.

Our own aircraft that move forward to deal with the situation are likely to suffer heavy losses as a result.

However, if Zhu Yongshun's method is adopted, there may not be enough time to determine the deployment plan, resulting in it being completely ineffective...

……

Perhaps because of the high-intensity work in recent days, after thinking for a while, Li Jianqiang suddenly felt an unbearable fatigue.

Although he didn't fall asleep on the spot, he was a little reluctant to open his eyes again.

Zhu Yongshun thought that his boss was in deep thought, so he naturally would not interrupt him.

So, the whole office fell into silence again.

Until a confidential staff member hurriedly appeared outside and knocked on the door:

"report!"

The loud voice woke Li Jianqiang, who was half asleep and half awake.

People who often take naps will know that the key to a nap is not the length of time, but a short nap of more than ten minutes is the best.

And Li Jianqiang is in this state at this time.

The sleepiness I felt just now was almost gone.

"Director Li, there is an urgent letter from Gaojing!"

The man at the door was holding an envelope with a seal on the opening. "From Gaojing?"

Li Jianqiang was stunned for a moment, then realized that this was most likely sent from Chang Haonan.

He stood up suddenly, walked around the desk and came forward.

He almost knocked over the teacup on the table.

After taking the envelope, he quickly confirmed that he was the recipient, and then opened it as quickly as possible.

Inside was a document that was half typed and half handwritten.

It's not very thick, maybe twenty pages.

《Temporal and spatial synchronization and phase calibration technology of bistatic radar》

The title at the top of the first page made Li Jianqiang's eyes light up.

Chang Haonan had not contacted him before, but he directly guessed what technology they needed.

But soon, a trace of shame appeared on his face again——

Mr. Chang has already delivered the latter part of the work, but I'm still stuck on the first half of the work. It's really embarrassing.

Thinking of this, Li Jianqiang sighed lightly, then went back to his desk and began to read the main text carefully.

Zhu Yongshun, who was sitting on the sofa next to him, was also itching to read it, but there was only one copy of the document, so he had to hold it in for the time being and wait for the other party to finish reading it first.

However, as soon as he turned the first page, he noticed that Li Jianqiang's expression and movements were obviously stagnant.

Then it instantly turned into ecstasy.

The latter placed the document on the table and rapped the table several times with his right knuckles:

"Old Zhu, the problem is solved!"

Zhu Yongshun was totally unprepared for this sentence:

"what?"

After a few seconds, I gradually realized:

"What does that mean? ... What new technology did Academician Chang propose to optimize radar resolution?"

"That's not it."

Li Jianqiang waved his hands, unable to hide his excitement:

"What Academician Chang proposed is a set of spatial correlation ambiguity functions for a single-transmitter, multiple-receiver radar!"

"Single send, multiple receive... Space related..."

Zhu Yongshun muttered a few words, and his thoughts became clear:

"This is an algorithm related to the radar deployment method. In other words... the solution I just proposed... can be used?"

"That's right!"

Li Jianqiang's voice trembled a little:

"Academician Chang also provided an example..."

He flipped through the documents to a page at the back:

"found it!"

Zhu Yongshun no longer cared about maintaining his decency. He stood up and walked to Li Jianqiang's desk, ready to study the example with him.

Although it is called an example, the actual situation cited is almost exactly the same as this time.

They just need some fine-tuning afterwards.

"System A, point 1, deployment coordinates... located in Jingnan City, Min Province."

"System A, point 2, deployment coordinates... located in Cangnan County, Zhejiang Province."

"System A 3 o'clock..."

"System B..."

Chang Haonan’s plan includes three sets of single-transmit, dual-receive dual-base radars.

However, because several of the points can be shared, a total of six points are physically required.

Two transmit, four receive.

The most important one is point 3 of the C system, which is the last launch point.

Coincidentally, due to space constraints, the previous page only wrote about point 2 of the C system located in Hecheng, Zhejiang Province.

Therefore, Li Jianqiang couldn't wait to turn to the next page:

"Deployment coordinates..."

Before he could finish turning the pages, his eyes widened slightly:

"and many more……"

"This is... at sea?"