Chirp chirp - "A series of bird like sounds came, proving that the underwater communication machine had received the signal from the mother ship. The experiment was successful Eight master's and doctoral students who have been fighting at sea for half a month shouted together. These "00s" who have already taken the lead in experiments come from the Harbin Engineering University Underwater Communication and Positioning Technology Innovation Team (hereinafter referred to as the "Team"). For many years, the team has harbored the dream of building a strong maritime nation and has developed a deep-sea acoustic positioning system known as the "thousand mile eye" and "windward ear", providing reliable underwater communication and positioning technology support for major ships such as the "Striver" and "Jiaolong". This year, the team was awarded the 28th China Youth May Fourth Medal. Upgrading underwater acoustic communication technology "To develop and utilize the ocean effectively, convenient underwater communication and positioning equipment is necessary. Our team aims to design a deep-sea acoustic positioning system for underwater equipment," said Sun Dajun, a team member and professor at Harbin Engineering University. Over 20 years ago, China's deep-sea acoustic positioning system relied on imports. In order to change this situation of being controlled by others, Sun Dajun and other young teachers started with basic theoretical research and embarked on the path of tackling problems. At first, foreign colleagues believed that we could not successfully develop it. But we firmly believe that as long as we work hard, nothing is impossible Team member and professor at Harbin Engineering University, Zheng Cui'e, recalled that she studied under Sun Dajun for her master's degree in 2004 and has been involved in the development of deep-sea acoustic positioning systems since then. Afterwards, after more than 10 years of hard work, the team continuously overcame difficulties, starting from building the basic theoretical "foundation" and gradually building an innovative "building" for underwater acoustic positioning in China. Nowadays, the deep-sea acoustic positioning system developed by the team is assembled on multiple scientific research ships in China. The underwater environment can cause serious interference to the propagation of sound signals. At first, underwater communication equipment was like walkie talkies, and the transmission and reception could not be synchronized. We want to improve the efficiency of underwater acoustic communication, making it as convenient as making a phone call on land Team member and professor at Harbin Engineering University, Qiao Gang, said. Since 2009, Qiao Gang has led young researchers to conduct research on full duplex underwater acoustic communication technology. However, the complex underwater environment and many other unfavorable factors have led to slow research progress. But the team members did not give up and overcame the difficulties step by step. They innovatively developed an underwater communication machine with full duplex communication and networking capabilities, ushering underwater communication from the era of "walkie talkies" to the era of "telephones". What are the mysteries of detecting Arctic sea ice and ice formation beneath Arctic glaciers? What are the impacts of greenhouse effect on glacier melting? This is a problem that has long plagued scientists worldwide. Due to global climate change, the thickness and coverage of Arctic sea ice have decreased, which has a huge impact on the acoustic environment and sound field patterns under polar ice. New acoustic theories and information processing technologies are urgently needed, "said Yin Jingwei, a team member and professor at Harbin Engineering University. Since 2014, under the leadership of Yin Jingwei, the team has taken the lead in conducting research on the characteristics of underwater acoustic fields and underwater detection and communication technology in China, and has developed integrated technology for underwater communication, detection, and positioning across ice layers. The Arctic waters are covered with thick ice caps, making it extremely difficult to conduct underwater acoustic research. In order to obtain first-hand data, the team selected Professor Han Xiao from Harbin Engineering University to conduct scientific research in the polar regions in 2018. He used experimental instruments and equipment independently developed by the team to conduct research on the noise field, sound propagation characteristics, and underwater acoustic communication under polar ice. After several months, Han Xiao successfully completed the relevant experiments and obtained a large amount of valuable underwater acoustic data, solving the problems of stable underwater acoustic communication and cross ice medium communication under polar ice. China has effectively observed the ice morphology of Arctic sea ice using satellites and other means, but there has been a lack of effective methods for detecting the ice shape and morphology beneath the ice sheet. In order to meet the detection needs, the team began developing equipment for detecting the shape of Arctic sea ice in 2010. In 2023, the Harbin Engineering "Xinghai 1000" polar exploration unmanned submersible, equipped with a multi beam ice detection sonar independently developed by the team, will deeply dive under the Arctic ice sheet, allowing Chinese researchers to clearly observe the ice bottom morphology of Arctic sea ice for the first time and obtain a large amount of key ocean parameter information. Facing challenges and bravely overcoming difficulties. On the eve of this year's Spring Festival, a team of more than ten people tested the performance of the prototype on a snowy ice lake. The low temperature of minus 30 degrees Celsius caused the prototype battery to instantly "power down", and they took off their military coats to "warm" the battery. During that time, the mountains were blocked by heavy snow, and vegetables could not be transported to the site. The water transported to the experimental site froze into ice. The team members completed the experiment under the condition of "lacking vegetables and water". The team's testing ground is often located in deep-sea areas and remote islands, with an average annual testing time of over 200 days. During the Chinese New Year holiday, they often have to send their longing to their families from afar on the ship at sea. In October 2020, the "Striver" successfully dived over 10000 meters in the Mariana Trench in the western Pacific Ocean. Team members Zhang Wenbo and Ji Xiaofeng, PhD students from Harbin Engineering University, experienced discomfort due to seasickness and even vomited while ensuring the deep-sea positioning of the submersible. At the end of the nearly 30 day scientific expedition, both of them lost 10 pounds. The deep-sea experiment has a long cycle, which poses challenges to both our psychology and physiology Wang Yuncong, a team member who recently participated in the sea trial and a doctoral student at Harbin Engineering University, said, "We float on the sea for one or two months, and when we encounter strong winds and waves, we can't even stand up. We often spit out a mouthful and record a data." "Technology from research and development to practical application is a long road. We will experience 81 difficulties on the road and gradually mature through passing the test." Sun Dajun's words were almost well-known to the team. This tenacious spirit has guided the team step by step to where they are today Team member and Harbin Engineering University teacher Han Yunfeng recalled, "More than 10 years ago, the team undertook a national key project to develop a positioning system for scientific research ships. We had already conducted a large number of experiments in the laboratory without any problems, but as soon as we went into the sea, we couldn't find the signal. After adjusting the parameters for several days in a row, everyone was almost unable to hold on, but Sun Dajun didn't complain and led us to repeatedly investigate and withstand it." Guan Guan passed with difficulty. In recent years, the team has repeatedly entered the "no man's land" in the field of underwater acoustics in China and even the world, achieving full chain innovation from original theory to technology research and development, and then to practical applications. In the future, they will continue to forge ahead, braving the wind and waves. (New Society)