Chapter 303: Can the distance measurement be accurate?

Although Mr. He looks like a rough guy, he is actually smart. When he heard what Gao Zhendong said, he immediately reacted and thought, hey, there is a way.

"Director Gao! Vice President Gao! Don't keep us in suspense. I will do whatever you say. I will hit wherever you point me. What good things do you have to take care of us?"

It's true, although the person who got to know Gao Zhendong first was General Guan, who was in charge of armor, but if we compare the number of good things that were obtained from Gao Zhendong, it was undoubtedly Comrade Lao He, who was in charge of firepower.

Fin-stabilized armor-piercing discarding sabot projectile, ESR gun steel, self-tightening barrel, and stable weapon. There is no way, Gao Zhendong's fear of insufficient firepower is also in the late stage, because he has personally been suppressed by the enemy's firepower on the battlefield.

So this disease, in its late stages, cannot be cured and can only be treated conservatively.

Among conservative treatment prescriptions, the most effective one is undoubtedly to fight poison with poison.

As the saying goes, "When you are poor, you should use tactics to infiltrate; when you are rich, you should bomb me."

Therefore, it is no surprise that Lao He got more good stuff from Gao Zhendong. He said that he was from the "direct line of troops", which was a joke, but it was not entirely unreasonable.

Gao Zhendong first asked a question: "What is the biggest problem you encountered in the process of fire control?"

Lao He did not hesitate at all. This problem had been turning over in his mind countless times, and he had thought of countless ways to solve it.

"Distance! It must be distance!"

If you don't know the distance, no matter how good the ballistic performance of the artillery shell is, the fire control will be useless.

The difference between tanks and infantry is that the effective engagement distance of infantry is about 400 meters, and within this range it can be estimated roughly by visual observation, which can be used to set the scale of the sight, but the engagement distance of a tank over a thousand meters is impossible to estimate accurately.

Most scopes at this time used optical ranging, which has a nice name, but is actually just an estimate. It just uses technical means to make the estimate more accurate, but it is not actually that precise.

A typical optical ranging technique is scaled ranging, which uses the ranging curve in the sight to cover the target. Since the height or length of the target is relatively typical, such as people are all 1.7 meters long and tanks are all 8 meters long, when the target is exactly the same height or width as the curve, the corresponding distance value on the curve is the target distance.

Needless to say, the accuracy of this method is limited. The inconsistency of the targets, the inaccuracy of the human eye's readings, the coarseness of the distance measurement scale, etc., all mean that this method can only provide an approximate measurement.

After hearing Mr. He's answer, Gao Zhendong, who had expected this, asked with a smile, "Optical distance measurement, right? Is it accurate?"

This silenced Mr. He. He shook his head and said, "To be honest, it is not accurate. It is greatly affected by the proficiency of the personnel. In actual use, an error of more than 10% is not uncommon. Vice President Gao, are you going to improve the distance measuring equipment? Use this DJS-60D?"

Gao Zhendong shook his head: "We'll talk about the DJS-60D later. You're right, I am indeed planning to improve the distance measurement method."

General He was delighted when he heard this: "Great! This thing has been bothering us for a long time. Now it is not unusable, and the troops have not raised too many objections. But we know that this thing is not very accurate, especially at long distances and in complex weather conditions."

The reason why the troops don't raise too many opinions is that they haven't seen anything better.

An inch longer, an inch stronger. Even if you have a good cannon, it is useless if you can't hit the enemy at a long distance. You still have to get close to the enemy and fight with bayonets. Then the meaning of a good cannon is reduced by half. After all, the distance is close, so even if the enemy's cannon is of average power, the threat is greatly increased.

Gao Zhendong asked: "Have you done any preliminary work? Tell me about it."

When it comes to business, Mr. He becomes serious.

"We first considered radar, but after talking to the radar guys, we found that radar is fine in the sky, but it can't handle clutter on the ground, and the beam is too wide, so we have no idea what we are measuring in front of us."

The radar technology at that time was probably like this, and it could not support this demand at all.

"We also thought about infrared, ultrasonic and so on, but we couldn't solve the problems of poor directivity, insufficient power, short distance, susceptibility to interference, etc. In short, it still didn't work."

Gao Zhendong smiled and said, "Have you ever considered a new technology, laser?"

Mr. He's eyes lit up, but soon dimmed again: "I have considered it. I considered it when lasers first came out, but there are still many problems."

Gao Zhendong said: "Tell me about it, we'll see if we can solve it."

Mr. He was not too hopeful about this, after all, lasers were too new. But after all, Mr. Gao's brain was better than his own, so maybe there was hope if he talked about it.

"Putting aside all the theoretical and practical engineering application problems, the first problem is that light travels too fast. We haven't found a fast enough timing method to calculate how long it travels. We calculated that if we want to achieve a measurement accuracy of 1 meter, we need a circuit that works at a frequency of at least 150MHz. We don't have an oscillator that fast, and the reliable ones we have are only about 10MHz."

Laser rangefinders do not need computers as controllers and converters, but they need at least a short enough time as a benchmark to measure the time of light flight. Of course, there are ways to not count time, but that method is not suitable for tank laser rangefinders.

Oscillators, though not very impressive, provide the most basic working rhythm for almost all digital circuits: pulses. In the future, when people often say that the CPU main frequency is XG, they are actually referring to this thing, which determines the working speed of digital circuits. Although GHz and THz are often mentioned in the future, the most basic oscillations, such as crystal oscillators, are generally below 100MHz. As for such high working frequencies, they are all made on this oscillation using other technical means.

In 1960, oscillators above 100MHz were relatively elusive in China.

Seeing that Gao Zhendong did not interrupt or raise any questions, knowing that Gao Zhendong could understand these things, he continued speaking.

"It's not impossible to achieve this frequency using other methods, but we have discussed with comrades in electronics, such as multi-stage series second harmonic circuits, third harmonic circuits, etc. However, the pulses produced by that method are uneven, which is not very useful for measurement."

After listening to this, Gao Zhendong didn't say much, but said something that made Mr. He overjoyed: "I will solve this problem for you, you can continue to talk about other things."

The reason Gao Zhendong said this is that he knows how to solve this problem, and the answer is ready.

——Phase-locked loop circuit, PLL.

The typical characteristics of the multi-frequency circuit composed of a phase-locked loop are high precision and very stable output, and it is widely used in communication, measurement and other circuits.

Although the most common phase-locked loop circuit in the future is the digital phase-locked loop integrated circuit chip, Gao Zhendong happened to have built a phase-locked loop circuit directly with discrete components when he was working on a project with his supervisor in his junior year.

Thanks to his smart brain, he remembered it very clearly. Although the working conditions, parameters and components are different, the circuit can be modified.

Mr. He never expected that Vice President Gao would solve the first problem so clearly. He rubbed his hands excitedly and said, "Thank you, Vice President Gao, thank you, thank you."

It feels like happiness comes too suddenly and I can't wrap my head around it.

The other comrades who came with him looked at Gao Zhendong's calm expression, and then thought about the difficulty of the problem he solved. They could only lament in their hearts that the gap between people was too big.

Gao Zhendong wrote this down on a piece of paper and said, "If you have any other questions, continue."

Mr. He thought for a moment and said, "The second reason is that this laser technology is so new that we know nothing about its technical principles, application methods, and test methods. We did buy the first issue of Laser, but I couldn't quite understand it."

Gao Zhendong smiled: "This is why I asked you to stay for a while. I will teach you about lasers."

The comrades at the Grassland Tractor Factory felt like they had found their organization, and they all felt that they had found their organization. Although Vice President Gao was young, he was really willing to step up when something happened.

Mr. He was a little hesitant. It wasn't that he didn't believe in Gao Zhendong's ability, but he was worried about something else: "Vice President Gao, isn't it a waste of your time for you to take time out to learn about lasers and then teach us?"

He knew that Vice President Gao had a lot of work to do. For their project, he had to learn everything about lasers and then teach them. This would be a huge waste of time, and he couldn't afford it.

Gao Zhendong looked bewildered: "Learn? I don't need to learn."

"Ah, Vice President Gao has already learned it?"

Gao Zhendong looked at Mr. He with an expression that said, "Don't you know?" and said, "Laser was invented by me. If nothing else, it's no problem for me to teach you."

This was said quite "modestly", but he forgot that others really didn't know.

Mr. He:? ~~~! ! ! !
other people:!!!!!!!

Old He suddenly had the urge to open Gao Zhendong's brain to see what it looked like.

"Vice President Gao, this is really beyond our expectations. Hey, I didn't expect that there is such a big Buddha among the people I know, hehe."

Although they don't understand lasers, they can still understand the various praises in the reports. Apart from anything else, the words "first in the world" can explain everything.

Gao Zhendong waved his hand: "It's not that exaggerated, haha, I'm just lucky and it happened smoothly."

Vice President Gao, if you don't know how to be humble, you don't have to be humble.

"Any other questions?"

"Gone? No, it's not gone. It's just that I haven't found it yet. After all, I haven't learned the principle and I don't have the ability to find the problem." Mr. He is very single. I can't do it. I don't have it.

(End of this chapter)