Chapter 1195 Deployment Location Is at Sea?

Li Jianqiang's third request was finally met.

However, with Chang Haonan's current status, he certainly couldn't just call people over.

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

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

After receiving foreign aid, we will consider how to upgrade the software and algorithms based on the existing radar.

Therefore, as soon as he returned to the research institute, he immediately gathered all his subordinates who had no urgent work at hand for a meeting, explained the current basic situation, and assigned specific tasks respectively.

However, things did not go as smoothly as expected.

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

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

The most troublesome one is that the anti-stealth principle of dual/multi-base radars uses the scattering of electromagnetic waves, and this scattering shows irregular characteristics to a large extent, and the transmitter and receiver belong to different radars. terminal, so it is difficult to use traditional technologies such as cluster analysis, matched filter sampling, and narrow-band automatic gain control for dense multi-target resolution.

In other words, within a relatively small range (more than ten kilometers to tens 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 properties are.

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

This is quite fatal in a confrontation.

For four or five days in a row, Li Jianqiang had a headache from this.

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

"Otherwise... we settle for the next best thing?"

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

"Tell me what you think."

The former really had no idea at this time, so he could only answer with the mentality of treating a dead horse as a living horse doctor.

“It is possible to add a second (bistatic) receiver to a monostatic radar system (coordinated transmitter and receiver), so that the monostatic radar system acts as the primary detection sensor, and the bistatic receiver assists it. Detect the target.”

Zhu Yongshun said, pulling out a piece of paper from the side and drawing a schematic diagram on it while continuing to introduce:

"The monostatic radar system can be used as the primary detection sensor, and the bistatic receiver assists it in detecting the target. The area of ​​concern of the transmitter is divided into the annular range unit of the monostatic radar receiver and the elliptical annular range unit of the bistatic radar receiver. divided into grids.”

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

This proposal was not difficult to understand, so he was interrupted by Li Jianqiang halfway through his words:

"etc……"

"According to the composite configuration method you mentioned, the entire solution will change from a complex multi-base radar network with multiple transmitters and multiple receivers to a simple bi-base radar network with multiple single transmitters and multiple receivers... In this way, it is equivalent to deploying radar Several additional constraints are added to the position out of thin air, and the calculation difficulty increases exponentially. "

Zhu Yongshun, who had the key point revealed by this word, 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 signal-level fusion of echo information... Let alone whether our current technical capabilities can support this, even if Academician Chang brings the solution to We also need the underlying architecture support of the radar itself, which cannot be solved by making minor repairs to the current model. "

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

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

But since others are causing trouble in the name of joint exercises, it is impossible for the aircraft dispatched to be only stealth aircraft.

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

The own aircraft that goes forward for disposal is likely to suffer heavy losses as a result.

But if Zhu Yongshun's method is adopted, it may be too late to determine the deployment plan, resulting in it being completely ineffective...

…

Perhaps it was because of the high-intensity work in recent days. After thinking about it for a while, Li Jianqiang suddenly felt an unbearable tiredness.

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

Zhu Yongshun thought that his boss was deep in thought, so he couldn't interrupt.

Therefore, the entire office fell into silence again.

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

"Report!"

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

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

And Li Jianqiang was in this state at this time.

The sleepiness just now was almost swept away.

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

The man at the door held an envelope in his hand, and there was a seal on the opening. "From Gaojing?"

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

He stood up suddenly and walked around the desk to meet him.

He even almost knocked over the teacup on the table.

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

Inside was a half-printed and half-handwritten document.

It was not thick, about twenty pages.

"Time-space synchronization and phase calibration technology of dual-base 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 the technology they needed.

But soon, a trace of guilt appeared on his face again--

Mr. Chang had already sent the latter part of the work, but he was still stuck on the first half of the work, which was really embarrassing.

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

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

However, just after turning over the first page, he noticed that Li Jianqiang's expression and movements were obviously stagnant.

Then he instantly turned into ecstasy.

The latter put the document on the table and slammed the table with his right knuckles:

"Old Zhu, the problem is solved!"

Zhu Yongshun was totally unprepared for this sentence:

"Ah?"

After a few seconds, he gradually reacted:

"It means... Academician Chang proposed a new technology to optimize radar resolution?"

"That's not the case."

Li Jianqiang waved his hands, and his excitement could not be hidden at all:

"Academician Chang proposed a set of spatial correlation fuzzy functions for single-transmitter, multiple-receiver radars!"

"Single-transmitter, multiple-receiver...spatial correlation..."

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

"This is an algorithm related to the radar deployment method, which means...the solution I just proposed...can it be used?"

"That's right!"

Li Jianqiang's voice trembled a little:

"Academician Chang also attached an example..."

He flipped the document to a page at the back:

"Found it!"

Zhu Yongshun didn't care about maintaining his dignity at all, and got up and came to Li Jianqiang's desk, ready to study the example with the latter.

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

They only need to make some fine-tuning later.

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

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

"A system 3 point..."

"B system..."

Chang Haonan's plan includes three sets of dual-base radars with single transmission and dual reception.

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

Two transmissions, four receptions.

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

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

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

"Deployment coordinates..."

Before the page turning action was completely completed, his eyes widened slightly:

"Wait..."

"This is... on the sea?"