Beidou Satellite Breaks New Underwater Communication Technology for the First Time, Making Chinese Nuclear Submarines More Concealed

According to Wang Fan, director of the Institute of Oceanography at the Chinese Academy of Sciences and the Yantai Coastal Zone Research Institute, the major breakthrough of this voyage is the first real-time transmission of large capacity data from deep-sea submersible markers using Beidou satellites. This independently developed technological achievement overcomes the difficulties of small payload capacity, low power supply, and large data volume of deep-sea submersible markers, changes the history of relying on foreign communication satellites, and improves the safety, autonomy, and reliability of real-time transmission of deep-sea data. Wang Fan also said, "Another major breakthrough in this year's voyage is that we have integrated inductive coupling and underwater acoustic communication technology to achieve real-time transmission of deep-sea data at a depth of 6000 meters for the first time. We have achieved real-time transmission of temperature and salinity flow data every 100 meters in the upper layer of the ocean and every 500 meters in the middle and deep layers of the oceanAlthough the report did not disclose details such as data transmission volume or quality, it is believed that if these technologies are developed, they will greatly enhance the underwater communication capabilities of Chinese Navy submarines, especially strategic nuclear submarines. In the future, the whereabouts of Chinese Navy nuclear submarines will become even more elusive when diving in deep oceans.As is well known, the biggest advantage of submarines is their ability to use thick seawater to cover themselves, with extremely excellent concealment. However, while seawater has obscured the submarine's movements, it has also caused great difficulties in communication for the submarine. Due to the high conductivity of seawater, ordinary radio waves are quickly lost when they enter seawater. This is because the shorter the wavelength and higher the frequency of electromagnetic waves, the more severe the attenuation in seawater. Therefore, microwave, shortwave, and ultra shortwave communication equipment commonly used on the ground and sea cannot be used for submarine communication in underwater navigation. Similarly, submarines are unable to communicate with shore based command centers, aircraft, and ships underwater using wireless communication equipment. If the submarine floats and communicates with the shore finger through wireless communication, it will soon be intercepted and located, and thus be attacked. The current radio signal interception and positioning technology has reduced the positioning time of a sudden communication frequency signal to less than 1 second. So for safety reasons, the communication principle of submarines has long been to only receive and not send.

In this way, submarines are actually isolated from the outside world when diving underwater, which is very unfavorable for modern joint operations. Moreover, submarines do not transmit signals underwater, but they must still receive information or instructions. So, in order to enable submarines to communicate effectively with the outside world underwater, people have been searching for communication technologies that can penetrate seawater.Through careful analysis of radio waves, it has been found that low-frequency waves have a certain degree of penetration into seawater. The lower the frequency and the longer the wavelength, the deeper the penetration of seawater. So, low-frequency radio was used for underwater communication. The earliest low-frequency communication used for shore to submarine communication was very low frequency (VLF) communication, also known as very long wave communication. The transmission attenuation of very low frequency in seawater is relatively small, with a depth of 10-30 meters. Very low frequency radio signals propagate between the Earth's surface and ionosphere, with distances ranging from thousands to tens of thousands of kilometers, enabling global communication for submarines. Moreover, very low frequencies propagate stably in the atmosphere, are less affected by nuclear explosions, ionospheric disturbances, magnetic storms, and have strong anti-interference and high reliability. So far, very low frequency communication remains the main means of submarine communication for navies of various countries. Submarines use buoyancy to tow antennas, which can receive signals at a depth of about 50 meters underwater.However, the depth of entry for very low frequency communication is not large, and submarines can only navigate at a low speed of 4-6 knots during communication, which greatly limits underwater maneuverability. In view of this, people have developed ultra-low frequency (SLF) communication, also known as ultra long wave communication. The signal attenuation of ultra-low frequency in seawater is only a fraction of that of very long waves, and it can reach depths of up to 100 meters. It is currently the only practical technical means for remote and deep underwater communication of submarines.

When conducting ultra-low frequency communication, submarines usually use buoyancy towed antennas with a length of 600 meters, which can receive signals underwater at 120-180 meters and a speed of 30 knots, greatly improving the submarine's concealment and underwater maneuverability.In order to enable submarines to receive signals at greater depths, the United States and Russia are also researching extremely low frequency (ELF) communication, also known as extremely long wave communication. This type of communication can enter water depths of over 200 meters (250-270 meters at a frequency of 10 hertz), indicating strong underwater communication capabilities. However, the difficulty of extremely low frequency communication is too great, and a very long antenna is a very tricky technical problem. Therefore, extremely low frequency communication has not yet been put into practical use.Although very low frequency and ultra-low frequency have largely solved the problem of underwater communication, the transmitters and antennas of these two communication methods are very large (such as ultra long wave antennas, even if they take one eighth of the wavelength, the shortest length is over 100 kilometers, and the required transmitter power is in the megawatt level), with long construction time, high investment, high operating costs, poor survival ability, and can only send information instructions to submarines but cannot receive submarine information. The transmission rate is also very low (for example, the US Navy's ultra-low frequency transmitter can complete a 3-character code set in 15 minutes, far from meeting the needs of sending complex combat instructions, usually only used to send short command codes or as a "ringing" to notify submarines to receive messages). Therefore, It cannot satisfy the navies of various countries, Finding new underwater communication technologies is also something that countries have been doing.According to Xu Ruilin, a maritime safety expert at Nanyang Technological University in Singapore, submarines are usually unable to transmit data on their own unless they raise communication buoy antennas or float to the surface. However, once the submarine does so, it will significantly increase the risk of being detected. By transmitting data through satellites, not only can the whereabouts of submarines become more elusive, but the transmission efficiency is also higher.

The underwater communication technology developed by China involves placing a floating object on the water surface for real-time data transmission, which is connected to underwater communication buoys through both wireless and wired methods. The submersible transmits data to the floating object, which launches it onto the satellite, which then feeds back to the ground. Adam Ni, a China expert at Macquarie University in Australia, said that this underwater communication technology will play a significant role in enhancing the combat capabilities of the Chinese Navy's submarine fleet. He pointed out that in addition to advances in submarine stealth technology and complementarity with a powerful surface fleet, this latest technological breakthrough is an important symbol of the modernization of China's navy submarines, especially nuclear submarines.However, some analysts believe that there are still shortcomings in this underwater communication technology, namely that the positions of the deployed underwater communication beacons are relatively fixed and easily destroyed by the enemy during wartime. So, it can only serve as an auxiliary underwater communication means for submarines.(Taken from Today's Beidou)

According to Xu Ruilin, a maritime safety expert at Nanyang Technological University in Singapore, submarines are usually unable to transmit data on their own unless they raise communication buoy antennas or float to the surface. However, once the submarine does so, it will significantly increase the risk of being detected. By transmitting data through satellites, not only can the whereabouts of submarines become more elusive, but the transmission efficiency is also higher. The underwater communication technology developed by China involves placing a floating object on the water surface for real-time data transmission, which is connected to underwater communication buoys through both wireless and wired methods. The submersible transmits data to the floating object, which launches it onto the satellite, which then feeds back to the ground. Adam Ni, a China expert at Macquarie University in Australia, said that this underwater communication technology will play a significant role in enhancing the combat capabilities of the Chinese Navy's submarine fleet. He pointed out that in addition to advances in submarine stealth technology and complementarity with a powerful surface fleet, this latest technological breakthrough is an important symbol of the modernization of China's navy submarines, especially nuclear submarines. However, some analysts believe that there are still shortcomings in this underwater communication technology, namely that the positions of the deployed underwater communication beacons are relatively fixed and easily destroyed by the enemy during wartime. So, it can only serve as an auxiliary underwater communication means for submarines.