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  When Lin Hong had almost finished eating, Cook began to talk about amateur radio, which attracted Lin's attention.

  Feng Wan couldn't get a word in edgewise at this time.

  Xu Wenjing could still chat a few sentences at the beginning, but as the topic deepened, she could only sit aside and stare blankly like Feng Juan, watching these two men, big and small, chattering away.

  From specific practices and improvements of the mining machine, to common styles of Yagi antennas, to international competitions between hams...

  Lin Hong's mastery of wireless technology was far beyond Cook's expectations. He didn't think that Lin Hong, at such a young age, had already made such great achievements in the field of wireless technology. Many of Lin Hong's ingenious ideas and improvements made him exclaim "Oh, God!"

  It turns out that Cook's ham age is over ten years old, and in their ham circle, his technical level has always been among the top. But today, he encountered a teenager in China who was only in his teens, and his technical level seemed to be even more impressive than his own, which made him feel extremely shocked.

  Cook and Lin Hongyu chatted more and more happily, when they were excited, Cook even asked the waiter to bring paper and pen, and the two began to draw on the paper.

  Early on, the hams were basically people with higher IQs. With high IQ comes natural arrogance, so soon their discussions between the two gradually turned into a technical undercurrent competition.

  Showing fellow travelers the techniques you've researched and new problems you've discovered is a very delightful thing.

  However, Lin Hong's superb skills gradually made Cook call for help, so Cook threw out some difficult problems that they usually encountered in their circle and were still in the argumentation stage. The most representative one is how to better separate the effective signal mixed with noise in today's increasingly electromagnetic interference signals.

  This is not only a problem in the amateur radio community, but also a problem in the entire radio community. Major research institutions and governments around the world are investing heavily in researching this technology. Obviously, this technology has been widely used in military applications for some time, but various departments have kept it confidential, considering it highly classified, and have not opened it up to civilians.

  So hamsters can only rely on their own strength to study. Although some results have been achieved in this area, the effect is not so satisfactory.

  Cook threw out this issue, just to prop up the door, indicating that he had already studied it quite deeply, which is pretty cool.

  He looked at Lin Hong with a smug expression, implying "I've already researched this far, want to see it?"

  At this moment, Cook is no longer a high school teacher, but a pure ham, just like a competitive little kid.

  Lin Hongyu looked at him with disdain, picked up the pen on the table and quickly drew a circuit diagram on the white paper, then pushed it over, without saying a word.

  Cook looked at him in puzzlement and then glanced at the circuit diagram.

  What does it mean? A very simple signal separation circuit?

  He went up and took another look.

  It makes some sense to add a resonant circuit on the signal separation circuit.

  Cook picked up the paper and held it in front of his eyes for a careful examination.

  It's not that simple, although it's based on a separate circuit, but has made some major changes, and there is also a signal amplification circuit here.

  Cook's brow furrowed.

  Is this design okay? No way, it seems like it will be less destructive?

  His eyebrows furrowed even more tightly.

  It seems it won't burn out, and the feedback current just neutralized it.

  This design is indeed very clever, but why did you do it this way?

  He looked at Lin Hong with a hint of surprise and began to examine him carefully.

  This circuit is just composed of several most basic circuits, but when combined, the completed function is completely different.

  The overall part formed two other large circuits, Cook concentrated his mind on these two circuits, he simulated them in his mind for half a day before thinking clearly about the two circuits, both of which were used to filter signals. One is filtering strong signals, and the other is filtering weak signals.

  "This design is great, but as far as I know, the filtering effect of these two large circuits isn't very good? The strong signal and weak signal circuits will also filter out the effective signal at the same time." Cook raised his own objections.

  "No," Lin Hong replied confidently at once. "Notice that there is also a noise-generating circuit on the side."

  Cook hastily shifted his gaze back to the blueprint, and indeed found a very hidden noise circuit in one corner. Its function was simple, just generating noise, so the circuit was also very simple, equivalent to a harmonic oscillator, which could be done with two or three components.

  Seeing this circuit, Cook was even more puzzled.

  Wasn't it supposed to filter out noise? Now you've gone and designed a noise circuit into it, isn't that just going to make the background noise even louder?

  He looked at Lin Hong with a puzzled expression.

  Lin Hong seemed to have anticipated that the other party would not understand.

  He took out another white paper from the table, drew a horizontal line and a vertical line, dividing the white paper into four parts. In the upper left corner and lower right corner, he wrote a word "bck", which means black color.

  "We look at this paper like this and can clearly distinguish where it is black and where it is white, right?"

  "Right." Cook nodded.

  Lin Hong turned the paper over, drew a few more lines, dividing the white paper into 16 small squares, and then colored every other square black. After finishing, he picked up the paper and said, "How's this? Is it harder now?"

  Cook didn't understand what he meant and didn't answer.

  Lin Hong couldn't help it, mainly because the conditions didn't allow for expression, and drawing by hand was too slow. He suddenly saw Cook's suit and had an idea, pointing at his gray suit and saying: "This suit, can't it be considered as being composed of two colors, black and white?"

  "Yes." Cook nodded. Although the suit looked gray, it was actually made up of black and white colors, only because of the dense black and white alternating small grid that created this visual illusion.

  "If we use connected black and white colors to paint, the visual effect is very poor. However, if we use small dots of alternating black and white to paint, we can create a three-dimensional effect painting with a clearer picture, and some details can also be expressed, isn't it?"

  Cook nodded involuntarily as he recalled the sketch.

  Lin Hong saw him nodding and finally let out a sigh of relief. To illustrate this principle was really not easy, he continued to say:

  "I found that this phenomenon also exists in audio. After filtering the signal through two circuits, one strong and one weak, the effect doesn't seem to be very good. However, by actively adding a bit of noise and introducing a specific amount of error, the overall received signal effect is actually better..."

  After his explanation, Cook remembered a small story from World War II.

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