Scientists in China have developed a new tech that can reportedly help detect a low-frequency sound source originating from the extreme depths in waters. Developed by scientists at Harbin Engineering University (HEU), the acoustic technology could help detect underwater vessels with near-perfect accuracy in the Arctic’s Beaufort Sea.
The area is of strategic importance for the naval operations of the United States as it’s a critical gateway to Alaska.
Chinese scientists have claimed that with the help of new tech, they can pinpoint the depth of a low-frequency sound source. However, they admitted the fact that submarine hunts in Arctic-like conditions could be affected by rapid ice melt, a sudden Pacific water influx or any other type of sudden environmental changes.
Passive depth-discrimination method
Published in Acta Acustica journal last month, the peer-reviewed paper revealed that HEU scientists could develop a passive depth-discrimination method using challenging Arctic oceanographic conditions. Reports have claimed that the method could be 93% accurate in detecting underwater targets and 100% effective in identifying surface vessels.
Researchers have claimed that their tech is a significant achievement in boosting China’s underwater warfare capabilities. Reports highlighted that the latest achievement has been verified through a computer simulation that was developed using data from China’s Arctic expedition conducted in 2020.
Sonar systems face challenges in Beaufort Sea
Sonar systems, which use sound waves to detect and analyze objects underwater, have faced challenges in Beaufort Sea’s (a marginal sea of the Arctic Ocean) “double duct” acoustic environment. In such places, a layering of water masses with contrasting temperatures and salinities creates hurdles for the sonar system to detect vessels.
Previous studies have highlighted that the lower duct impacts the propagation of various active signals used commonly for acoustic communications or active sonar.
In the latest study, Chinese researchers highlighted that the upper surface duct (0-80 metres, or 0-263 feet) exhibits increasing sound velocity with depth while the Beaufort duct (80–300 metres) forms a distinct sound channel” due to warm water coming from the Pacific.
The team led by Professor Han Xiao from HEU’s National Key Laboratory of Underwater Acoustic Technology stressed that when a sound source is located within the Beaufort duct, a portion of horizontally propagating acoustic energy becomes trapped in the sound channel, avoiding energy losses caused by sea ice reflection and scattering, reported SCMP.
“This acoustic trapping capability provides new opportunities for long-range under-ice communication, navigation and both active/passive detection systems,” said researchers.
Passive sonars could play key role in submarine detection
There has been a growing need for enhanced sonar to operate more effectively in icy environments, similar to the environment of the Arctic and sub-Arctic regions.
Environmental sensing technologies were also touted to play major role in overcoming these challenges.
Although, passive sonars — which use use hydrophones for listening — have been a preferred choice when it comes to submarine sonars. These sonars depend on detecting and analyzing acoustic signatures from the environment.
However, high frequency active sonar — which use acoustic transducers and power for sound output — are still much effective in tackling mines and dealing with obstacle avoidance.
In the latest study, Chinese researchers have also highlighted that using existing sound detection methods in such scenarios could give an incorrect estimation of the depth of the target, which may lead to weak decision-making during naval combat.
The team also examined the data from China’s recent Arctic explorations and revealed that ocean layers could play a challenging role in underwater combat. They believe that lower-pitched sound waves in Arctic could jump between ocean layers. However, this is expected to be impacted by the frequency of the sound waves.
By tracking where these sound waves cluster and measuring their strength at different depths, the team said they could now pinpoint the depth of a 600Hz underwater target with unprecedented precision – and with simple listening devices. The method can also filter out noise from the environment, enabling accurate tracking using as few as six sensor arrays – a critical advantage in icy, turbulent waters, according to SCMP.
