Chapter 1195: The 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 bi/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.
"Say 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 configuration of 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 circular 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 is not difficult to understand, so he was interrupted by Li Jianqiang halfway through his words:
"Wait..."
"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 sentence, 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 In front of us, 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 tangled 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 a certain distance away to ambush, then a simple multi-base radar will only detect a single and obvious echo signal, but cannot 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 personnel hurriedly appeared outside and knocked on the door:
"Report!"
A loud voice directly woke up Li Jianqiang, who was half asleep.
People who often take naps will know that the key to a nap is not its length, but a nap of more than ten minutes is the most effective.
And Li Jianqiang was in this state at this time.
The sleepiness just now was almost gone.
"Director Li, there is an urgent message from Haojing!"
The person at the door was holding an envelope in his hand, with a seal attached to the opening. "From Hao Jing?"
Li Jianqiang was stunned for a moment, and then realized that this was probably sent from Chang Haonan.
He stood up suddenly, walked around the desk and came forward.
He even almost knocked over the tea cup on the table.
After taking the envelope, he quickly confirmed that the recipient was him, and then opened it as quickly as possible.
Inside was a half-printed, half-handwritten document.
It's not too thick, about twenty pages.
"Spatial-temporal 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 the technology they needed.
But soon, a look of shame appeared on his face——
Chang has already delivered the rest of the things, but he is still stuck on the first half of the work, which is really a bit embarrassing.
Thinking of this, Li Jianqiang sighed softly, then returned to his desk and began to read the text carefully.
Zhu Yongshun, who was sitting on the sofa next to him, was also itchy, but there was only one copy of the document, so he had to endure it for the time being and wait for the other party to read it first.
However, just after turning the first page, he noticed that Li Jianqiang's expression and movements were obviously stagnant.
Then it turned into ecstasy in an instant.
The latter put the document on the table and banged the table with his right knuckle several times:
"Lao Zhu, the problem is solved!"
For this sentence, Zhu Yongshun can be said to be unprepared:
"Huh?"
After a few seconds, I gradually realized:
"Meaning... What new technology has Academician Chang proposed to optimize radar resolution?"
"That's not true."
Li Jianqiang waved his hand, his excitement couldn't be hidden at all:
"What Academician Chang proposed is a set of spatially correlated fuzzy functions for single-emitter and multi-receiver radar!"
"Single sending, multiple receiving...space related..."
Zhu Yongshun muttered two sentences, and his thoughts became clear:
"This is an algorithm related to the radar deployment method. In other words...the plan I just proposed...can it be used?"
"That's right!"
Li Jianqiang’s voice even trembled:
"Academician Chang also attached a calculation example..."
He flipped the document to a certain page at the back:
"Found it!"
Zhu Yongshun didn't care about maintaining his dignity at all. He got up directly and came to Li Jianqiang's desk, preparing to study the calculation example with the latter.
It is said to be an example, but in fact the actual situation cited is almost exactly the same as this time.
They just need some fine-tuning later.
"A system point 1, the deployment coordinates...are located in Jingnan City, Min Province."
"A system point 2, the deployment coordinates... are located in Cangnan County, Zhejiang Province."
"System A 3 points..."
"System B..."
Chang Haonan's plan includes three sets of dual-base radars with single transmitter and dual receiver.
However, because several of the points can be shared, a total of six points are physically required.
Two to launch, four to receive.
The most important one is point 3 of system C, which is the last launch point.
Coincidentally, due to space reasons, the page just mentioned only points 2 of System C located in Hecheng, Zhejiang Province.
Therefore, Li Jianqiang couldn't wait to turn to the next page:
"Deployment coordinates..."
Before the turning of pages was completely finished, his eyes widened slightly:
"Wait..."
"This is... at sea?"
(End of chapter)