Is there any technical difficulty in playing underwater drones?

According to relevant media reports, on December 15, the Chinese navy captured an American UUV in the South China Sea and took it away. The US called on China to return the submersible immediately. The Ministry of National Defense of China stated that it will hand over it to the US in an appropriate manner.

However, when I saw that the motherland was so "reasonable", I was relieved by Xiaobian.

What is the "unmanned Underwater Vehicle" UUV (unmanned Underwater Vehicle)?

UUV (Unmanned underwater vehicle) is an unmanned, remotely controlled or automatically controlled underwater navigation device. It mainly refers to high-risk underwater operations such as deep sea detection, life saving, and mine removal instead of divers or manned small submarines. Intelligent system. Therefore, unmanned submersibles are also referred to as "dive robots" or "underwater robots".

Unmanned submersibles can be divided into military and civilian applications according to their application fields. In the military field, unmanned submersibles can be used as a new concept weapon in unmanned combat platform weapons. Even without weapons, this type of detector can replace humans to investigate and study various basic hydrological information related to submarine operations in the ocean. In a sense, the role of an unmanned submersible is similar to that of a drone.

How does this play in the water?

Can I use the "Heaven and Earth 9" 2.4G remote control remote control?

Does not!

In the process of electromagnetic wave conduction, the most ideal state is to propagate in vacuum. At this time, in the process of propagation, there is no obstacle of other substances, and the propagation of radio waves is not affected. In the water, it is another world.

Due to the attenuation effect of seawater on electromagnetic waves, the electromagnetic wave propagates in water with a strong attenuation, and the electromagnetic wave is not linearly attenuated in water, it is attenuated exponentially, and the attenuation is fast. The shorter the wavelength, the greater the attenuation; the higher the conductivity of water, the greater the attenuation. To the "2.4G" remote control band just mentioned, because the water molecules are more powerful for the electromagnetic wave attenuation in this frequency band, the electric wave may only be attenuated after being injected into the water for a short distance. This can be roughly analogous to the attenuation of light waves in water.

Of course, there are also ways of using radio wave communication, such as ultra-long-wave and very long-wave signals that the submarine receives the radio unilaterally under water. (The wavelength of ultra-long waves is 10,000 to 100,000 meters, and the wavelength of extremely long wavelengths is more than 100,000 meters.) However, such communication is subject to the constraints of antenna size and power equipment, and the information transmitted in unit time is small and inefficient, and cannot be Meet the needs of high transmission rates.

This picture vividly shows the communication bands used by various submarines.

Method for correctly controlling UUV of unmanned submersible

1, using fiber-optic wired communication technology: UUV with a long "tail" into the water. (No explanation)

Cast a cable controlled UUV

2, the use of underwater acoustic wireless communication technology: underwater acoustic communication is one of the most mature technology. Sound waves are the main carrier of underwater information, and have been widely used in underwater communication, sensing, detection, navigation, positioning and other fields. The typical propagation velocity of sound waves near the sea surface is 1520 m/s, which is 5 orders of magnitude lower than that of electromagnetic waves. Compared with electromagnetic waves and light waves, the attenuation of sound waves in seawater is much smaller, but the rate and communication bandwidth are still limited.

3. Underwater quantum (laser) communication technology: transmitting information using a laser carrier. Since the blue-green laser with a wavelength of 450 nm to 530 nm is much less attenuated underwater than other optical bands, the blue-green laser is used as a window band for underwater communication. The advantage of blue-green laser communication is that it has the highest transfer rate in several ways. At super close distances, the rate can reach 100 Mbps. The blue-green laser communication has good directivity and a small receiving antenna.

This technology may be related to satellite quantum communication technology.

Summary: There are three main types of underwater wireless communication: underwater electromagnetic wave communication, underwater acoustic communication and underwater quantum communication, which have different characteristics and applications.

Of course, we have always been sensible and ethical. After picking up something in the sea, I still have to return it to the owner. Just I guess, be sure to ask questions before the exchange:

"Hello, is this UUV that you lost? In order to confirm my identity, I opened it and saw that you have returned it to you!"