How to make a submersible make sound from the deep sea?

The deep sea has always been beautiful and mysterious, attracting us to go deep into the seabed and explore more secrets. Therefore, many countries have begun to study manned deep-sea diving technology.

Many people are curious about how submersibles communicate with the ground in the deep sea. Liu Yeyao, a pilot of the "Struggler" manned submersible and a senior engineer at the Institute of Acoustics, Chinese Academy of Sciences, explains this question in detail.

When studying manned deep-sea diving technology, the scientific research team encountered many problems. Many key components were developed in cooperation with foreign countries, but some equipment was controlled by foreign technology, such as underwater acoustic communications.

Hydroacoustic communication is the only bridge of communication between the submersible and the mother ship, and it is an indispensable device for manned submersibles. Without hydroacoustic communication, when the submersible is diving, it cannot receive the signal from the mother ship or loses contact, and it is impossible to determine how long it will take for the submersible to surface and stop operations.

Before the Jiaolong, foreign manned submersibles all used analog communication technology, just like a walkie-talkie, where two people on the surface and underwater had to shout to each other to establish a connection between the submersible and the mother ship. my country's independently developed high-speed digital underwater acoustic communication is much simpler than analog communication technology. The underwater acoustic communication technology can autonomously exchange data between the submersible and the mother ship, saving a lot of time and operating steps, allowing scientists to focus more on checking the operation of the submersible, underwater sampling and other tasks, which improves the work efficiency of the submersible. In addition, the underwater acoustic communication technology can also exchange data with the mother ship for many key information in the submersible at regular intervals, avoiding problems such as slips of the tongue or failure to observe when reporting.

What are the difficulties in deep-sea acoustic communication technology? Liu Yeyao said that the first difficulty is distance. The key word of underwater acoustic communication is communication. For example, when two people are talking, the farther the distance, the louder their voices need to be, but this is limited. Corresponding to the human body, the "voice" of underwater communication is the sound source level mentioned in aquatic science. Because of the limitations of energy, lines, equipment structure size, etc., the sound source level cannot be increased infinitely.

The second difficulty is to enhance the received signal. For example, when someone hears you speaking, even if the voice is very low, they may be able to hear what you are saying. For underwater acoustic communication technology, it needs to have strong anti-noise and signal detection capabilities. To achieve these, it is necessary to study a very good communication algorithm.

In addition to conducting in-depth research on underwater acoustic communication technology, Liu Yeyao and his research team have also made many improvements to the submersible's positioning system. For example, they have improved the algorithms and some engineering application-level equipment and hardware, making the submersible's positioning system increasingly stable.

Science and technology are the strong foundation for a country to gain a foothold in the world. The unremitting efforts of scientific researchers are to make the equipment localized in my country and enable my country to have more independent intellectual property rights. Liu Yeyao hopes that more young and middle-aged people can participate in national scientific research and hope that everyone can do something meaningful at the best and most suitable age to contribute to our country.

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