Image Credits: Wikipedia China has created a database of underwater sound data from warships that its submarine crews can use when trying to identify or find a surface vessel again after losing contact, the country’s Ministry of National Defense said. The system was recently used in a simulated fight between a Chinese submarine and a surface warship. The opposing ship changed its speed and direction several times to make tracking harder. Chinese sonar operators checked the contact against information in the database, including its frequency and speed, and managed to pick it up again. This could help the People’s Liberation Army Navy (PLAN) keep track of surface ships in difficult underwater conditions. It could also add to the work facing U.S. anti-submarine warfare forces, which use P-8A Poseidon aircraft, MH-60R Seahawk helicopters, surface ships and submarines to search for and track hostile submarines. China Builds Database From Naval Training A ship’s machinery and propulsion systems produce sounds that can be detected underwater. Those sounds can change when the ship speeds up, slows down or operates under different machinery conditions. Chinese naval personnel have been recording this type of information during training, exercises and deployments. Instead of leaving the information with individual sonar operators, the PLAN has brought it together in a central database. The project followed an earlier exercise in which Chinese submarine crews struggled to keep track of another ship. Heavy waves created enough noise to hide some of the vessel’s underwater sound, making the target harder to follow and nearly costing the Chinese side the simulated engagement. Chinese naval personnel later worked with military research institutes and equipment manufacturers to bring together acoustic data that had previously been kept in separate places. The database now includes information on different target types, along with new data collected during exercises, training and de