Into Unscientific

"Doppler effect?"

   Hearing the word that came out of Xu Yun's mouth.

  Old Guo was taken aback for a moment.

   As a physicist who has studied abroad for many years, Lao Guo is naturally no stranger to the Doppler effect.

   This is a physical phenomenon discovered by Christian Doppler in 1842. To put it bluntly, in one sentence:

  The wavelength radiated by an object will change due to the relative motion of the wave source and the observer.

  For example, when standing still and an ambulance is coming, the sound heard is higher than before.

   And when the car leaves, the sound is lower than before, which is the Doppler effect.

  The essence of this phenomenon is that when the ambulance drives towards a person, it emits sound waves continuously, and the sound wave emission position is getting closer and closer to the person.

  So the arrival time of each sound wave is shorter than the last sound wave, and the distance between the peaks, that is, the wavelength, will be shortened accordingly.

  So the frequency of the sound waves perceived by the human body increases and the pitch rises.

Similarly.

   When the ambulance leaves.

  The sound source of the sound waves emitted is getting farther and farther away, causing the wavelength to increase, the frequency to decrease, and the pitch to decrease.

  This is a physical phenomenon that was proposed and concluded very early, and there is no mystery or application value in itself.

It can be said like this.

Up to now.

  This effect has almost no supporting application technology.

  So after Xu Yun said the word.

  The expression on Lao Guo's face was not relieved, but became more and more confused:

   "Comrade Han Li, I have a little understanding of the Doppler effect, but what does it have to do with increasing data sampling?"

   "What we need is more sample data, and there seems to be no intersection with acoustic Doppler?"

  Xu Yun nodded when he heard the words, but he was not in a hurry, but said patiently:

   "Yes, the Doppler effect of existing physics mainly occurs in the macroscopic field, such as ambulances and the like."

   "But don't forget that the real core of the Doppler effect is not macro, but relative motion."

  Old Guo was taken aback for a moment.

  Xu Yun didn't pay much attention to Lao Guo's expression, and continued:

  “In the macroscopic world, the relative movement of people and cars is reflected in the fact that the car moves and people don’t move—this is also everyone’s subconscious cognition, because this example is so easy to understand.”

   "But the essence of the Doppler effect is to accept changes in frequency, that is, the macro situation can be that the car whistles but does not move, and people slowly walk towards the car."

   This time.

  Old Guo nodded slightly.

  Just like the author who thinks of the novice fisherman when talking about tentacle monsters, in life, people often use some of the most classic examples to replace a certain concept for interpretation.

But in fact.

  Cases and concepts are not completely equivalent, just like in addition to novice fishermen, there are tentacle monsters such as eagles and so on at the starting point.

  Doppler effect is the same.

  The example of an ambulance can clearly explain the Doppler effect, but it is not the actual cause of the effect itself after all.

Do not know why.

  When he heard Xu Yun's words, the outline of a huge monster appeared in his heart

   Then Xu Yun tried his best to pull out his hand from the quilt, drew a circle in the air with his index finger, and signaled:

   "Guo Gong, you should know that according to the principle analysis of the Doppler effect, this phenomenon is also established in the microscopic field."

   "That is, those who move towards the stationary ambulance can actually be replaced by various particles, such as precipitation particles and rain particles."

   "In addition, the dielectric constant of each particle is different, for example, water is 0.93, ice is 0.18, etc."

   Say it.

  Xu Yun clenched his left hand on a high place, raised a finger on the bottom of his right hand, and said:

   "Then Guo Gong, suppose I mean hypothesis."

   "If there is such an instrument, when it is in operation, it can be biued from time to time, and emit some electromagnetic waves of special bands into the sky."

   "At the same time as it emits the waveband, particles with different dielectric constants are also moving on the cloud layer."

   "These movements are irregular. Some may go up and down, some may move to the left and some may drift to the right. Some draw an S and some draw a B, but in short, they will move relative to the instrument."

   "In this way, what do you say will happen after the electromagnetic waves come into contact with them?"

  Boom—

  Xu Yun's words were like thunder from the sky, and they exploded in Lao Guo's heart instantly.

  For Lao Guo, who majored in physics, this question is simply a free question. It is so simple that it cannot be simpler.

   But also because of this.

  Old Guo Cai became more and more afraid to make a judgment.

  “.”

after awhile.

  Lao Guo just adjusted his glasses with his trembling left hand, and slowly gave an answer:

   "If a target particle is moving closer to the instrument, the reflected wave will have a higher frequency than the emitted wave."

   "If the target particle is moving away from the instrument, the frequency of the reflected wave will be lower than the frequency of the emitted wave."

  “At the same time, due to the difference in dielectric constant, different particles will scatter to different degrees, and what is fed back to the instrument is a different degree of frequency shift.”

   "Through this frequency shift, the real-time atmospheric turbulence can be reversed."

   Said the last.

  Old Guo suddenly leaned back on the chair, let out a deep breath, and remained silent.

   It's been a long time.

  Lao Guocai raised his head again, looked at Xu Yun slowly, and asked with a delicate expression:

   "Comrade Han Li, does this instrument have a name?"

  Xu Yun didn't hold back this time, and replied directly:

   "Yes, it's called Weather Doppler Radar."

   That's right.

   Meteorological Doppler Radar.

   This is the big killer that Xu Yun thought of when he took out the damper!

Doppler effect.

   This is a classic physical phenomenon that has been proposed for nearly a hundred years in this era.

  When Xu Yun finished the 1850 copy, he met its proposer Christian Doppler in Cambridge University.

  This effect is also widely used in later generations, involving a large number of military and civilian fields.

   Such as meteorological Doppler radar, color Doppler ultrasound, Doppler imager, etc.

   There are also students who are often ticketed for speeding. The speed radar that detects your speeding records also relies on the Doppler effect.

But on the other hand.

   These Doppler technologies, which were popularized by later generations and could no longer be popularized, were almost not developed until the 1970s.

  That is to say, during the 130 years from 1842 to 1970, there was almost no physical technology to benchmark the Doppler effect.

  The main reason why ‘almost’ is used here is that sonar detection is related to the Doppler effect.

   But it does not appear by virtue of the Doppler effect, it can only be regarded as barely related.

  The earliest Doppler effect instrument in human history is

   Meteorological Doppler Radar.

  The principle of meteorological Doppler radar has been introduced once above, so I won't repeat it here.

  Its concept was proposed in the early 1960s, and its actual application will be in a certain period of time close to the 1970s. The specific time is too sensitive and will not be described in detail.

  In short, in the current period of time, the meteorological Doppler radar does not even have a physical object across the sea, and even the design process has only reached about 40%.

   As for the first weather Doppler radar in China, it was even later.

  In China, it was not until the end of the 1980s that the National Meteorological Administration and the 784 factory in Chengdu successfully developed the first S-band 714SD and the first C-band 714CD Doppler weather radar prototypes.

   Yes, this is just a prototype.

   As for the first meteorological Doppler radar that was actually put into use, it was not until 1992.

   Before meteorological Doppler radar radar.

  Meteorological radar in the field of meteorology can only make qualitative analysis through echoes, otherwise the first numerical weather prediction in human history would not have appeared until 1954.

  The line of sight returns to reality.

   Right now.

  Lao Guo leaned back on the wooden chair provided by the hospital, muttering the name repeatedly:

   "Weather Doppler Radar"

  While speaking, his heart was full of emotions.

  As a professional physics practitioner.

  Although Lao Guo has not seen the real thing Xu Yun said.

  However, based on the principles described by Xu Yun alone, it can be confirmed that the instrument he mentioned has a high probability of being operable and effective.

  And the data that this radar can collect is more than 100,000 times as simple?

   After all, there are too many particles in the atmosphere

  As long as the conditions are right, a million times or even tens of millions of times more data can be collected - then calculations will become a big problem instead.

more importantly.

   It's a weather radar!

To know.

  In the current scientific research field.

  Whether it is domestic or foreign, even Mao Xiong and the opposite side of the sea, their development level of weather radar is just like that.

  The first human weather radar appeared in 1943, which is less than 20 years away.

  At that time, the Massachusetts Institute of Technology designed a storm radar, which was mainly used for the location of storms. The principle was extremely primitive, and it is still in operation.

   Another example is the current domestic weather radar.

  The first domestic conventional weather radar landed three years ago. It was remanufactured by Lao Guo’s friend Baozheng through the military 843 altimetry radar. The full name is 703 radar.

  Its main purpose is only one:

   is used to predict typhoons.

It can be said like this.

   Today's weather radars around the world are basically used to observe large-scale meteorological disasters, such as typhoons, hurricanes, and so on.

   Other than that.

  Ordinary rainfall, snowfall, sandstorms, etc. They can't be predicted at all. In a sense, they are equivalent to a large telescope.

  But the meteorological Doppler radar that Xu Yun mentioned now seems to have opened up a new road to the sky in front of Lao Guo.

   Many, many years later.

  The day when Lao Guo and Xu Yun met was endowed with many special colors, and the communication between the two was also crowned with many inexplicable auras.

   For example, there is [a conversation that changed the history of mankind] that is stable.

   The ones who do the work are [Comrade, this is the password of your accelerator] and so on.

  Some people joked that this is [chicken and rabbit in the same cage], so it is called [pair in the cage].

   After a while.

  Old Guo completely 'digested' the shock in his heart, and then turned his attention to Xu Yun again:

   "Comrade Han Li, what processes and parts do you need to assemble this weather Doppler radar?"

  Old Guo didn’t ask Xu Yun if he could give an assembly plan. After all, Xu Yun once said one thing before:

  The investment of the entire equipment is about tens of thousands of dollars, and the time is as fast as three or four days, and as slow as seven or eight days.

   That is to say, Xu Yun must be clear about the specific steps, and even know some more detailed inside stories.

   "Parts"

as expected.

  Xu Yun touched his chin quickly, and said slowly:

   "Structurally speaking, a weather Doppler radar can basically be divided into eight links."

   "that is, antennas, radomes, signal processors, servos, transmitters, receivers, waveguides, and displays"

   "Comrade Han Li, wait a minute."

   Before Xu Yun could finish speaking, Lao Guo interrupted him.

   Lao Guo took out the paper and pen from his briefcase, put them on the table, and then signaled:

   "Please continue, Comrade Han Li."

  Xu Yun didn't care about it, nodded and continued:

   "The simplest ones are the radome and the display, not to mention the radome, as long as the display can show the echo and the vertical profile."

   "As for both the transmitter and the receiver, they can be temporarily improved with the hospital's X-ray machine—provided that the leaders can convince Dr. Lin Yu."

   "For the antenna, use a parabolic antenna for the positive feeder. The diameter is about 1 meter, and the feeder only needs to be horizontally polarized."

   Same as the engine.

   Small Doppler detection radar is also a very common device in the DIY circle of later generations.

  When Xu Yun was in Chengfei, he worked on this thing many times—although it was a small, low-power wind Doppler radar with a sensitivity of only -60dbm, the principle is still the same.

  Considering that the industrial level of the rabbits in this era is relatively low, and the time is more urgent at this time.

   Therefore, Xu Yun also used an old idea as always:

  Do not engage in the official version of equipment, only engage in the most cost-effective beggar cough cough, youth version weather Doppler radar.

  After all, Lao Guo and the others only need 50 million sets of data.

  The data collected by an ordinary weather Doppler radar in later generations is very exaggerated, often reaching tens of billions or even hundreds of billions of sets.

  For example, the very characteristic 'dolphin-style' radar tower in Jiuquan can even collect 300 billion sets of data at a time.

no way.

  There are too many particles in the atmosphere.

   Therefore, no matter the demand or the actual situation, Xu Yun does not need to produce the official version of the weather Doppler radar.

  In Xu Yun's design.

  The display can only consider the echo and vertical profile. For the Daniel of the 221 factory, it is only necessary to improve the TV screen.

  Transmitters, receivers, and waveguides can all be obtained locally from hospitals:

  The X-ray machine in the hospital has its own X-wave frequency, which can provide the X-band dual polarization effect required by the transmitter and receiver.

  The waveguide comes from the ECG monitor beside him—the string galvanometer and waveguide of this thing are almost the same principle.

   As for the servo system, it is not difficult.

  The servo system of later generations mainly uses servo amplifiers and pulse width modulators, such as SMPR-v1 or something.

  But students who have been Doppler radar in this life should know it.

  The essence of the servo amplifier in the weather radar is actually to drive the extension + pitch switch.

   As for the pulse width modulator, it is simpler, just apply force in two directions to achieve dynamic lubrication.

  So the latter only needs to ask the boss of the third branch factory to design an IGBT module, while the former needs a ready-made RC snubber circuit.

  Yes, RC snubber circuit.

   See here.

   Presumably some smart classmates have already realized it.

   That's right!

  The thermocouple hygrometer that is now placed on the watchtower just happens to provide a complete RC snubber circuit.

  “.”

A few minutes later.

  Looking at the words written all over the paper, Lao Guo couldn't help blinking, and asked Xu Yun:

   "Comrade Han Li, I have a question I want to confirm."

   "According to what you said before, the cost of a weather Doppler radar starts at around 20,000 to 30,000 yuan, right?"

   "However, from the perspective of these parts, the cost should not even cost 5,000 yuan. Where does the difference in this part go?"

  As an expert who has been engaged in aerospace engineering research for a long time, Lao Guo is very sensitive to information on equipment costs.

  He did a simple mental calculation just now, and when all the parts Xu Yun mentioned were added together, the cost would be at most four to five thousand yuan.

   Not to mention components like RC snubber circuits, which can be put back on the original device after use.

  So the actual cost is even a little smaller than the value he calculated.

   Four to five thousand versus twenty to thirty thousand.

   This is obviously not in line with what Xu Yun said before, and it is difficult to explain the past with reasons that do not understand the market.

  Looking at the bewildered Lao Guo.

  Xu Yun on the bed couldn't help but smiled, pointed to Lao Guo's notebook, and said:

   "Guo Gong, I'm afraid you haven't noticed that among the eight links I mentioned just now, there is one more that I haven't finished."

"There is still one?"

  Old Guo was taken aback for a moment.

  He was patronizing to record before, and only wrote down a rough outline of the project. Hearing this, he couldn't help but glanced at the notes again:

   "Antenna. Radome. Transmitter. Waveguide."

   After a while.

  Old Guo slowly raised his head and confirmed:

   "A total of seven parts, indeed one is missing. The signal processor."

  After speaking, Lao Guo realized something, and asked:

   "Comrade Han Li, is it possible that the cost of this part is very high?"

  Xu Yun glanced at him, with a hint of amusement in his eyes:

   "Guo Gong, let me tell you the truth."

   "This part is not a question of whether the cost is high or not, but"

   "The question of whether you dare to use it."

Note:

Tomorrow, I will ask for a day off at my hometown to worship the ancestors. I have to go after I haven’t worshiped the ancestors in three years, and there is a high probability that I will be torn apart (my ancestral hall is that kind of ancient dwelling, the land is very valuable, and my uncle’s house has been wanted since ten years ago. We sold part of the ancestral hall and shared the money. The rest of us disagreed. My dad said that there would be another quarrel this year)