China Uses Warship Sounds To Improve Submarine Target Tracking

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 deployments.

It also contains performance information from individual sonar operators.

Database Tested Against Maneuvering Warship

The database was later used during another exercise involving a blockade and a counter-blockade.

In that exercise, sonar operators used information already stored in the system to work out the movements of ships. A Chinese submarine then secretly moved through a simulated air-sea defensive network and carried out a simulated attack.

The more recent submarine-versus-warship exercise provided another test.

The opposing ship repeatedly altered its course and speed. Chinese sonar operators compared what they were hearing with earlier information in the database and were able to regain the target.

The value of the system is therefore not necessarily about allowing a submarine to hear a ship from farther away. Its purpose is to give crews more information when a contact becomes weak or disappears.

For example, if a submarine loses a ship on sonar, operators can compare a new contact with earlier observations. That can help them decide whether they are tracking the same vessel.

Possible Impact on U.S. Naval Forces

Chinese submarines could try to follow U.S. and allied surface ships operating inside the First Island Chain. Those forces would have to use anti-submarine measures to prevent Chinese submarines from maintaining contact.

U.S. carrier strike groups already use several layers of anti-submarine protection. These include P-8A Poseidon maritime patrol aircraft, MH-60R Seahawk helicopters, surface ships and attack submarines. Unmanned systems are also increasingly part of the anti-submarine warfare effort.

If Chinese submarine crews can recover lost contacts more reliably, U.S. forces could have to spend more effort finding and breaking those contacts.

Tankers, ammunition ships and transport vessels are needed to keep naval forces operating far from their home bases. They are generally less protected than front-line warships.

A submarine that can better work out what type of ship it is detecting could potentially use that information to distinguish a support vessel from other traffic.

How the Database Uses Sound

The information stored in the system includes several factors that can help sonar operators assess a contact.

A ship’s frequency provides one set of clues. Its speed gives another. The vessel’s machinery and propulsion state can also change the sound it produces underwater.

The PLAN is building the database from repeated observations made during exercises, deployments and training rather than relying on a single recording.

The system also includes information on the performance of individual sonar operators.

References: interestingengineering, armyrecognition