Back in 1978, I was admitted to Northwestern Polytechnical University.

Chapter 186 KJ-2000 Project
The middle-aged man on the ground jumped to his feet: "What did you say?"

He gripped Qin Liang's shoulders tightly, so hard that it hurt Qin Liang. His eyes were almost right in front of Qin Liang's face, and Qin Liang could see the excitement and agitation in them.

"Old Wang, don't get excited, don't scare Qin Liang," Old Lin said.

Lao Wang?

The man was of medium build with a thin face and wore a Zhongshan suit. Qin Liang searched his memory repeatedly, feeling that he had seen this person somewhere before. Could he be... the chief designer of the KJ-2000 early warning aircraft?

No, no, Mr. Wang should be at the 38th Research Institute right now, developing the 383 radar. How could he be in the KJ-1 development team?
"Mr. Lin, who is this gentleman?"

"The development of the KJ-1 airborne early warning and control system encountered difficulties, so after the Chinese New Year, some engineers from the 38th Research Institute came to help. This is Chief Engineer Wang from the 38th Research Institute."

It really is Old Wang! The father of the Eastern early warning aircraft!
Qin Liang warmly extended his hand: "Old Wang, it's a pleasure to meet you!"

Wang Gong scratched his head. He was only forty years old, and he was already considered old? He wasn't old at all, but... looking at Qin Liang's outstretched hand and thinking about the advanced technology that Northwestern Polytechnical University, which Qin Liang represented, possessed, he still reached out his hand.

"Comrade Qin Liang, Northwestern Polytechnical University has very advanced technology! We are looking to use computers for post-processing of data for our 383 radar, but we haven't been able to find suitable equipment... We hope that Northwestern Polytechnical University can lend a helping hand."

Previous homeland air defense radars were all two-coordinate systems, which could only know where the target was, but not its altitude. Only when the target got close would they be used in conjunction with a specialized altimeter radar to detect three-dimensional data.

The 383 radar was China's first domestically produced three-coordinate radar. More than a thousand people worked in remote mountain villages for seven or eight years. Just as the project was about to be finalized, the country opened its doors to the world!
The military is already examining various foreign radars, especially the American AN/TPS-43 radar, which is readily available and has a long detection range. Therefore, some people support direct foreign purchase to meet the military's needs. As for self-development... in recent years, everyone has been disappointed by self-developed products, and the gap with foreign products has been widening. Foreign purchases are needed to solve the pressing problem!
Engineer Wang came to help find the flaws in the KJ-1 airborne early warning and control system, hoping that if the 383 radar failed, he could still join the development of the KJ-1 and find a project for the 38th Research Institute. Otherwise, the remote, third-line base might...

Now, unexpectedly, we happened to run into people from Northwestern Polytechnical University, and what's more, Northwestern Polytechnical University has developed advanced radar technology!
Qin Liang felt the force coming from his hand and nodded vigorously: "Professor Wang, don't worry, Northwestern Polytechnical University will do its best to help! Whether it's ground radar or early warning radar, Northwestern Polytechnical University hopes that with our help, our equipment can reach the world's first-class level!"

"Sigh!" Old Zhou sighed from the side, "I didn't expect that our brother units already have advanced technology, such as flat panel slotted radar and fully digital processing technology... Compared to these technologies, our KJ-1 is really too backward! However, we have been working on the KJ-1 for so many years, and it was just about to reach the finalization stage. If we were to start all over again now..."

"I'm a little reluctant to part with it!" Old Zhou's gaze was complicated.

Xiang Zhongkai nodded: "That's right. We're all in the analog circuit business. If we're talking about building a brand new early warning aircraft, we probably won't be able to help much. Qin Liang, didn't you just mention a lot of noise filtering solutions? Tell us about them!"

Qin Liang nodded: "Okay, let me first introduce the single delay line technology. This technology requires two different input pulses before output, so it is called a dual-pulse canceller. The delay T is equivalent to the radar's PRI, and the output signal y(t) is y(t) = x(t) - X(tT). The pulse response of the canceller is h(t) = (t) - (tT), and the Fourier transform of h(t) is..."

As Qin Liang spoke, he picked up the drawing next to him, flipped it over, and began to draw waveforms.

"So, using delay line canceller technology can indeed eliminate noise, but... the response time is probably a bit slow, isn't it?" Engineer Wang said.

Qin Liang couldn't help but want to give Wang Lao a thumbs up. The father of the KJ-2000 is truly amazing; he discovered the problem so quickly.

“The response speed of a single canceller is unacceptable. The most critical problem is the lack of a wide stopband. To solve this, we need to upgrade to a dual-delay-line canceller, which will produce three different input pulses, also known as a three-pulse canceller… To further enhance the response, we also need to add a feedback loop to the circuit…” After listening to Qin Liang’s explanation, Old Zhou’s expression was complicated: “This technology can indeed eliminate echoes, but… to achieve such an effect, it would require soldering thousands of delay lines…”

"That's right. In vacuum tube circuits, this is the only way to remove noise. Only through digital transformation can we use the MTD algorithm to filter noise, and the performance will be better..."

MTD, Moving Target Detection, is a method that uses specialized algorithms, such as Doppler frequency shift, to detect the movement of a target. Vacuum tubes and transistors cannot compare to it; only digital circuits can do it!

If this is changed, wouldn't the entire project need to be scrapped and started from scratch? What would be the point of the entire R&D team then!
"Sigh, Professor Lin, we've really fallen behind. Northwestern Polytechnical University and Institute 607 can develop top-notch fighter jet airborne radar, so they should be able to develop advanced early warning aircraft. Our... our KJ-1 project, well..."

"President Zhou, please don't!" The others seemed to understand what Old Master Zhou was going to say, and they all spoke up, their eyes already filled with tears. They had worked hard for this Airborne Early Warning and Control System No. 1 for ten years, knowing the danger, they still rushed to get on the plane every time!
Is this project just going to be cancelled like this? They're not willing to accept it!

"You're reluctant, and so am I, but... we're already outdated. We can't deliver an outdated early warning aircraft to the military; that would be irresponsible to the military and the country! Leader Lin, on behalf of the KJ-1 development team, I formally request that the project be... cancelled."

As he said the words "dismount," tears streamed down Old Zhou's face; he couldn't control his emotions.

"It's good that the project was canceled." A relaxed voice rang out, and many people instantly clenched their fists, wishing they could rush up and punch someone!
"Mr. Lin, these comrades have extensive experience in the development of early warning aircraft. With them joining the research and development team, our Northwestern Polytechnical University and Institute 607, along with these comrades, will strive to develop an advanced early warning aircraft for the Air Force within two to three years. The project's specifications will be no less than those of the E-3. What do you think?"

Join the new early warning aircraft development team? Everyone's eyes widened. They hadn't been eliminated; they were still...

"Qin Liang, I know you mean well, but... we only know how to use vacuum tubes and analog circuits. These are completely new concepts..."

"Learn! You're never too old to learn!" Qin Liang said. "Do you guys know Old Tu? That old technical expert from Factory 132, after a year of learning, is now a master in digital circuits!"

“That’s right, we really should update our knowledge system, put aside this immature project, acquire new knowledge, and continue to serve the country and the army!” Old Zhou said with tears in his eyes.

"Hmm!" Everyone looked up at Elder Lin, their eyes filled with anticipation.

"On behalf of the Air Force, I express my strong support for this project. This new project is called..."

"How about the KJ-2000? This brand-new early warning aircraft can be used until after the new millennium!" Qin Liang said.

"Okay, let's go with the KJ-2000. It will replace the KJ-1 and become the new Air Force's top priority project!"

Sigh, shouldn't the Air Force's top priority project be the J-10 or a modified version of the J-9?

(End of this chapter)