Bright Sword Military System

Chapter 1359 Three-Ball Positioning System
This question made Wang Xuexin very embarrassed.

It is obviously not possible to use a tube computer. This is not only because of the volume, but also because the tube is a glass-wrapped vacuum tube. If this thing is used in a missile, the speed of the missile may reach more than 800 kilometers per hour in an instant... The impulse is enough to make the inside of the missile The glass tube was shattered in a mess.

So use a transistor?

But it took 47 years for the transistor to be invented, which is still four years away.

It is not impossible for Wang Xuexin to make this thing first, but if the research starts with transistors, then computers, and then applied to missiles... the water in the distance cannot quench the thirst of the near, and the Eighth Route Army urgently needs this missile for air defense.

Apart from other things, the devils at this time have opened up the north-south line of communication under the intentional retreat of the stubborn army, and the next step is to return to the division to besiege the Eighth Route Army. Or have to pay a lot of casualties.

How can we solve the problem of identification friend or foe?

The Mark 3 radar is difficult to do. It is a medium-wave radar after all, and the enemy's missiles, aircraft, and its own missiles flying in the air are just a point for it.

It is still possible to identify it at a long distance, and the computer can track and identify it according to the continuation of the track. This is the problem of Chen Jiefeng's programming.

However, if the distance between the target and the enemy is too close, within 300 meters, the radar has already regarded the two as the same target or exchanged, that is, the data input into the computer is wrong, and Chen Jiefeng can’t do it even if the program is perfect. identify.

If you can't do it with radar, you have to...

Wang Xuexin suddenly thought of something, and said, "Perhaps, we can position in another way!"

"Another way to locate?" Su Xin asked suspiciously: "Apart from using radar, is there any other way to locate?"

After Su Xin finished speaking, he turned his attention to Su Liguo, he is an expert in this field.

Su Liguo shook his head in a daze. After all, this is something that flies in the air, and with a speed of 800 kilometers per hour, he can't imagine anything other than radar.

Wang Xuexin said: "Comrades, have you heard of the three-ball positioning system?"

"Three-ball positioning system?" Everyone was dumbfounded when they heard this term.

Wang Xuexin slapped himself on the head. I'm afraid he is stupid... The three-ball positioning system is a modern GPS positioning method. How could scientists in this era hear about it.

Looking at the curious eyes of everyone, Wang Xuexin explained while drawing on the paper: "The principle is this. If we know the distance between the base station and the target, then we can draw a spherical surface with the base station as the center and the distance as the radius. , the target must be on this sphere.”

Everyone nodded one after another. Those here are either scientists or mathematicians. If you don’t even understand this, then you’re pretending to be a fool.

Wang Xuexin continued: "One base station can determine one sphere, then two base stations can determine two spheres. That is, the target is on the circle obtained by the intersection of these two spheres!"

This is also not complicated. The target is on this sphere and that sphere. Of course, it is to find the common point where the two spheres intersect. This common point is a circle.

At this moment, Su Liguo understood something, he said "Oh", and said: "If there are three base stations, you will get three spheres, and if the three spheres intersect, you will get two points, and one of these two points must be It can be ruled out below the ground, and the other point is the location of the target we want to locate!"

"That's right!" Wang Xuexin said: "This is the theory of the three-ball positioning system. It's actually not complicated, and the accuracy is very high!"

This is what modern GPS satellite positioning does. To serve so many units at the same time at such a long distance, GPS must use a simple, practical and accurate method, which is three-ball positioning.

According to the theory of three-ball positioning, if at least three satellites are required to work at the same time for accurate positioning, the three satellites know the distance between themselves and the target through the data connection with the positioning target, and then use the method of two-by-two intersection of three balls to calculate the target. s position.

So at least 24 satellites are needed to achieve global positioning... Only in this way can we ensure that there are at least 3 satellites in the sky above any point on the earth.

(Note: Most of the actual positioning uses 4 satellites, and the 4th satellite is used for calibration)
Su Liguo looked at the crowd and said, "Commander, we understand the theory, but how can we know the distance between the target and the base station?"

Wang Xuexin asked instead: "Old Su, do you still remember the mercury delay line memory?"

"This..." Chen Jiefeng asked suspiciously: "What does this have to do with distance?"

Wang Xuexin explained: "Mercury delay line memory uses a kind of ultrasonic wave. If we install this ultrasonic device on the missile and let it launch towards the ground base station, we know its time difference when its speed is known. Isn't it possible to calculate the distance between the two?"

This is a very simple physics formula: "distance = speed * time".

It's just that this distance is calculated using the speed and time difference of ultrasonic waves.

Su Liguo understood the meaning of Wang Xuexin's words. He said, "Commander, according to what you mean, we still need a launch time on the missile and a reception time on the base station?"

"Yes!" Wang Xuexin nodded and said, "The time difference can only be calculated with the launch time and reception time."

"But the leader!" Su Liguo said again: "The speed of the ultrasonic wave can travel 340 meters per second. As long as we have a one-second error in this time, it is meaningless to exceed the error of the radar!"

"So, we need a high-precision timer!" Wang Xuexin called out the quartz electronic watch directly from the system.

The production of a quartz electronic watch is not complicated. It uses the principle that the quartz crystal will produce very stable vibrations (32768 vibrations per second) under the influence of battery power, so it can be accurate to 32768ths of a second.

(Note: This is the reason why quartz watches are accurate. A rough quartz electronic watch has a daily error of no more than 0.5 seconds, and a well-made quartz electronic watch can achieve a monthly error of 0.1 seconds.

With a quartz electronic watch, the time difference can be accurately calculated.

The distance can be calculated with the time difference, and it is an accurate distance.

After calculating the respective distances, the missile can be accurately positioned with the three-ball positioning system...

Modern satellite positioning does the same, the difference is that the satellite positioning system uses a much more accurate atomic clock... It is said that the error of this thing is only 2000 second every 1 million years.

But of course, Wang Xuexin only asked for the location of missiles that were only a dozen or tens of kilometers away, and the quartz electronic watch could fully meet the requirements.

(Note: There are more detailed explanations of the three-ball positioning system on the Internet, as well as diagrams)

(End of this chapter)