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

The expressions of the other people standing behind Guo Lin were also very exciting.

Intuitively, they don't believe that someone can directly determine the design principle of the circuit in such a short time.

Mainly because it's too fast.

People who can enter the 14th Institute of Electrical Engineering are somewhat capable in circuit design.

But when you actually get a circuit board that has never been touched, is inherently damaged, and has a lot of new components, it will still take a few days to analyze it no matter what.

If you are facing this kind of military circuit board with many non-standard parts and electromagnetic shielding packages, you may have to collect some materials specifically.

After all, in this era, the transmission of information is really not smooth.

As for Chang Haonan's performance, their first impression seemed to be...

Looking at a circuit board that is already very familiar to me.

In this way, many intermediate processes can be omitted, and judgments can be made directly as long as some typical characteristics are found.

But how is this possible?

This pod was probably secretly produced by Raytheon Company. From the time it was captured to the time it was secretly transported back to Jinling, the number of people with knowledge of it was also controlled within a very limited range.

Chang Haonan, who had just arrived at Institute 14 today, had never had the chance to see the real thing even though he had heard some brief remarks from Guo Lin before.

But on the other hand, the person who said this was Chang Haonan after all.

And Xu Yang next to him did not express any objection.

If someone else made such a judgment, it would definitely be considered as lying.

But the situation of these two is different.

Although algorithm theory, software programs and circuit hardware can be regarded as three different fields, they are all under the category of control engineering after all.

After all, he wrote a paper that was on the cover of IEEE Transactions on Automatic Control.

All in all...it's quite confusing.

It should be said that these people's guesses were not wrong.

Chang Haonan was able to use a microscope to see the working principle of the jamming device, naturally not because he had the Sharingan, but because he had already made a guess before, and now he was just verifying it.

Or to be more precise, it is just to add some rationality to one's own judgment. Otherwise, it would be difficult for others to believe it if one just glances at it and tells the result directly.

In fact, he took advantage of the times.

In later generations, this kind of DDS can be integrated into an integrated circuit with a side length of no more than two centimeters, instead of a palm-sized circuit board like this, which is definitely not something that can be seen with an ordinary optical microscope.

Of course, it seems that it is still a bit beyond Guo Lin's ability to accept.

But it doesn't matter, it can be explained.

He just described it in words, which was indeed not intuitive enough. Moreover, everyone else was not mentally prepared. I am afraid they did not hear the whole story. It is normal to be dubious.

"Actually, although this board looks very complicated, the core principle is not difficult to understand. You are just scared by the origin and packaging specifications of this thing."

Chang Haonan took the circuit board off the microscope stage and gently put it back in place:

"Is there a blackboard? I can draw a picture of the principle and it will be easy to understand."

Guo Lin is the one who believes in Chang Haonan the most among everyone except Xu Yang. He just listened to the judgment given by the latter completely, but because he spoke too fast, he still didn't fully understand it. Now he naturally wants to catch him. Live this opportunity.

"There are some, right next door."

More than a dozen people came to a small conference room nearby.

Only Xu Yang didn't follow immediately.

After she explained in a low voice to Chang Haonan, she picked up several other circuit board fragments and observed them alone.

……

Sometimes Chang Haonan wonders whether the blackboards used by enterprises affiliated to the Science and Technology Commission system are purchased centrally.

In short, this room, this blackboard, and this chalk made him dream back to House 601.

"Although this direct digital frequency synthesis sounds like a scary new concept, we should all be able to understand the workflow."

Chang Haonan said and drew a simple schematic diagram on the blackboard:

"This is what it looked like after I deleted all the non-core components on that circuit board."

He didn't even need to repeat his previous explanation. The engineers from the 14 institutes surrounding the blackboard showed a look of understanding.

This is the role of peeling off the cocoon.

Just like some math problems, you can't find the idea at all when you do it for the first time, but after reading the answer or listening to the teacher explain it once, you will find it very simple.

“So the purpose of this thing is to perform carrier frequency shifting with higher efficiency?”

Soon someone figured out some important links.

"Yes, the DDS (Direct Digital Synthesizer) itself is just part of the Field Programmable Gate Array (FPGA)."

"Perhaps taking into account electromagnetic compatibility and stability issues, this FPGA was designed to be very large, and even three layers of circuit boards were stacked to achieve all functions."

Chang Haonan picked up the chalk again, added a dotted box around the picture he had just drawn, and wrote the three letters DDS inside. Then he drew several other components on the blackboard and connected them into a larger area. circuit.

"I understand!"

Guo Lin, who was standing closest to the blackboard, was particularly excited:

"The input radar radio frequency signal is mixed with the system local oscillator, and down-converted to an intermediate frequency signal through band-pass filtering (BPF); after the intermediate-frequency analog signal is mixed with the precise local oscillator and low-pass filtered (LPF), a baseband analog signal is obtained; ADC Under the control of the sampling clock, analog-to-digital conversion is implemented, and the output digital signal is stored in RAM; during the forwarding process, the read data is reconstructed into a baseband analog signal after being filtered by DAC and low-pass filtering; this reconstructed signal is consistent with the system local oscillator After mixing, the frequency is upconverted into a radio frequency interference signal..."

"..."

At the beginning, Guo Lin's analysis was very smooth, but later on, he realized that something was wrong:

"It feels like...it feels like there's a module that's not being used?"

Chang Haonan nodded:

"Well... this should be a transformation module used for orthogonal down-conversion processing, used to convert one intermediate frequency signal into two orthogonal components. As for the specific algorithm and the ultimate purpose of doing so, we still have to wait until Dr. Xu It was analyzed there, but if I had to guess, it might be to increase the bandwidth at a low sampling rate to ensure the interference effect on low-frequency radar..."

As soon as he finished speaking, Xu Yang, wearing a lab coat and without even taking off his goggles, pushed the door in from the outside and came to Chang Haonan:

"This should be an orthogonal dual-channel DRFM that can process two orthogonal components at the same time. Under the same sampling rate, the bandwidth can be doubled..."

As soon as she finished speaking, she found that everyone in the room was looking at her with strange eyes.

Or to be more precise, he looked at the small blackboard behind him.

So Xu Yang turned around subconsciously:

"Hey, so you've noticed it too?"

"That's not true."

Chang Haonan waved his hand and put the chalk on the table next to him:

"I reasoned it out."

The understatement made the whole room quiet for a moment.

"Ok."

A few seconds later, Xu Yang nodded with a complicated attitude:

"No matter what, there's still one thing I don't understand."

"According to this schematic diagram, there is no need to design the pod to be so bulky. It can be about 6 meters in length, so that some ordinary tactical aircraft can also be mounted normally."