China’s territorial claims in the South China Sea – through which about £3.9trillion in ship-borne trade passes each year – are contested by Brunei, Malaysia, the Philippines, Taiwan and Vietnam. In the East China Sea, disputed islands have soured relations between Beijing and Tokyo for decades, and led to tense stand-offs between Chinese and Japanese warplanes and ships.
As China flexes its military muscle in the South China Sea, the U.S. is responding with its own show of force that includes ships, fighter jets and submarines, as well as the test launch of nuclear-capable missiles. U.S. Navy carrier battle group centered on the aircraft carrier USS Carl Vinson has presence in the South China Sea, the stretch of Pacific bounded by China, Vietnam and the Philippines. Three attack submarines, the USS Alexandria, USS Chicago and USS Louisville, have deployed in the Western Pacific and at least one has entered the South China Sea.
China has bee engaged in upgrading its anti-submarine capability over the last few years through measures such as “Underwater Great Wall”, a string of submerged sensors, buoys and drone submarines and QUIDs. These projects will help China extend its offshore surveillance zone.
In June 2017, Satellite imagery has indicated Chinese aircraft have been deployed to the South China Sea. Photos taken by commercial firm DigitalGlobe in May show four submarine-hunters, three Harbin BZK-005 recon unmanned aerial vehicles and two KJ-500 early warning jets parked at Lingshui Air Base on Hainan Island. The Y-8X aircraft were put into service in 2015 but have not been documented at the Lingshui Air Base until now, according to Defense News. The submarine-hunter is the first combat-ready maritime patrol plane to be commissioned by China’s People’s Liberation Army Navy (PLA-N).
China itself is developing variety of submarine detection technologies like massive underwater surveillance system, SQUID magnetometer of this type could detect a sub from 6 kilometres away, and Caplin says that with better noise suppression the range could be much greater. recently they have also developed a technique to hide secret messages in the sound pulses that sperm whales emit to keep enemy reconnaissance systems from deciphering them – a breakthrough that could help military submarines avoid scrutiny, researchers said.
China Building massive underwater surveillance system
China is planning to build a massive underwater observation system across the disputed East and South China seas, that experts say could be used to detect the movement of foreign ships and diminish the stealth capabilities of US submarines. According to state-run broadcaster CCTV, the monitoring networks will cost two billion yuan ($290 million) and “serve as a platform to provide long-term observation data and support experiments in the research of the maritime environments of the two seas.”
Carl Thayer, a regional security analyst and emeritus professor at the University of New South Wales said, China “could use the cover story for this undersea network to lay sensors designed to detect the movement of surface warships and submarines in particular.” Such a system, said Thayer, “mitigates the stealth advantage that submarines have. This would be of direct concern to the United States and other regional states that operate submarines. Earlier One of China’s biggest shipping conglomerates has proposed building a network of ship and subsurface sensors to detect US and Russian submarines and to boost the nation’s control of the South China Sea, a UK-based news website reported.
The “Underwater Great Wall” is the construction of a network of ship and subsurface sensors that could significantly erode the undersea warfare advantage held by US and Russian submarines and contribute greatly to future Chinese ability to control the South China Sea, the report said. If the system is built by the corporation it would probably be bought by the PLA Navy, the article said. The corporation is proposing an improved Chinese version of the Sound Surveillance System that for a time gave the US a significant advantage in countering Soviet submarines during the cold war, the article said.
Chinese, scientists employ AI technology to help detect submarines in uncharted waters
Scientists from China and the United States have developed a new artificial intelligence-based system that they say will make it easier to detect submarines in uncharted waters.
The technology builds on earlier work by the team, led by Dr Niu Haiqiang from the Institute of Acoustics at the Chinese Academy of Sciences in Beijing, which saw them develop a deep-learning algorithm that could improve the speed and precision of detection. The algorithm, however, needs a large amount of data to work, so its use is limited to waters that have already been fully charted. In contrast, the upgrade works in all waters, charted or otherwise.
Niu and his colleagues, who included scientists from the Scripps Institution of Oceanography at the University of California San Diego, started by developing a simulator to generate a wide range of virtual environments from which the algorithm was able to learn. Once it had assimilated that information, the simulator was able to analyse real-life data taken from the world’s oceans and seas, the team said in a paper published in the July issue of The Journal of the Acoustical Society of America.
It is now able to help a single hydrophone locate more than 80 per cent of underwater targets within an uncharted area with a margin of error of less than 10 metres (33 feet), the paper said.
The researchers said the new technology should allow them to track any sound-emitting source – be it a nuclear submarine, a whale or even an emergency beeper from a crashed aircraft – using a simple listening device mounted on a buoy, underwater drone or ship. The scientists worked together to improve the sensitivity and accuracy of passive underwater surveillance technology, according to the academy’s website.
China has developed the world’s most powerful submarine detector
The Chinese Academy of Sciences, the country’s largest research institute, said in an article on its website that a “superconductive magnetic anomaly detection array” has been developed in Shanghai and passed inspection by an expert panel. The device could also be used on civilian and military aircraft as a “high performance equipment and technical solution to resources mapping, civil engineering, archaeology and national defence”, the article said. Researchers estimate that a SQUID magnetometer of this type could detect a sub from 6 kilometres away, and Caplin says that with better noise suppression the range could be much greater.
Magnetometers have been used to detect submarines since the second world war. They are able to do this because they can measure an anomaly in Earth’s magnetic field – like one caused by a massive hunk of metal. Anti-submarine aircraft have been equipped with magnetic anomaly detectors, or MAD, since World War II. The devices monitor the small disturbances metallic objects cause to the Earth’s magnetic field, analyse the data and use complex algorithms to calculate the object’s position. Precise locations are often difficult to obtain, however, because the strength of a magnetic signal drops rapidly as the distance from the source increases. Aircraft have to fly low, and the submarine has to be operating sufficiently close to surface for the device to register it. The power of the signal can be reduced by other factors, too, such as if the submarine is made from less ferromagnetic materials.
Thanks to something called the Debye effect, it might be possible to hunt submarines using the magnetic signatures of their wakes. Seawater is salty, full of ions of sodium and chlorine. Because those ions have different masses, any nudge—such as a passing submarine—moves some farther than others. Each ion carries an electric charge, and the movement of those charges produces a magnetic field.
Submarines produce many different types of wake. As well as the familiar V-shaped wake they leave underwater disturbances known as “internal waves”, flat swirls called “pancake eddies” and miniature vortices which spin off from fins and control surfaces. These all depend not only on speed and depth but also on the submarine’s hydrodynamics (the underwater version of aerodynamics).
Things are likely to get easier, too: a new generation of high-tech magnetic sensors based on machines called SQUIDs—“superconducting quantum interference devices”—should be more sensitive than existing ones.
The new magnetometer, built by Xiaoming Xie and colleagues at the Shanghai Institute of Microsystem and Information Technology, uses not one SQUID but an array of them. The idea is that by comparing their readings, researchers can cancel out some of the extra artefacts generated by motion. This “would be relevant to an anti-submarine warfare device”, says David Caplin at Imperial College London, who works on magnetic sensors. Researchers estimate that a SQUID magnetometer of this type could detect a sub from 6 kilometres away, and Caplin says that with better noise suppression the range could be much greater.
China’s military may soon adopt the technology, if it has not already, said Professor Zhang Zhi, an expert in remote sensing with the Institute of Geophysics and Geomatics, China University of Geosciences in Wuhan, Hubei. “The technology could be used to detect minerals on land, and in the ocean to nail down submarines,” Zhang, who was not involved in the project was quoted by the Post saying.
Not everyone is convinced the Chinese magnetometer is ready for deployment. Cathy Foley at CSIRO, the Australian government research agency, says there are several difficulties with turning a SQUID into a sub-hunter – for example dealing with background magnetic noise. Nobody has yet solved all of these problems, although she says the rate of Chinese progress means they may well be first to succeed.
Researchers report a low-temperature-superconducting (LTS) SQUID based full tensor gradient system. A symmetrical configuration is used with six planar-type gradiometers mounted on the different faces of a hexagonal-pyramid. A tri-axial SQUID magnetometer was used to compensate the imbalance outputs of each planar gradiometer. Direct readout electronics are used to further increase the system robustness.
The SQUID outputs are synchronized with a GPS + INS unit for coordinate projection. During indoor tests, a noise level of 100fT/m/√Hz with corner frequency at 10Hz and a static RMS resolution of 10pT/m(0.01-10Hz) were achieved. Principle demonstration was carried out by a ground test over a 10×10 m2 area using buried iron balls with different weights. The system successfully resolved the abnormalities of all the gradient components at the corresponding locations. The field test was also carried out using a helicopter.
Dr Lei Chong, an assistant researcher studying MAD technology at the Department of Micro/Nano Electronics, Shanghai Jiaotong University, said the Chinese device was different from conventional designs in at least two ways. The first is the large number of probes the device uses. With this “array”, it can collect much more data than traditional detectors, which tend to use just one antenna, said Lei, who was not involved in the project.
The new MAD also uses a superconductive computer chip cooled by liquid nitrogen. This super-cool environment significantly increases the device’s sensitivity to signals that would be too faint for traditional devices to spot. “I am surprised they made such an announcement,” Lei said. “Usually this kind of information is not revealed to the public because of its military value,” he said.
Chinese research teams have also recently completed the development of eight other types of magnetic detectors, some of which are small and sensitive enough to be used on satellites, the article said. The academy said that due to the difficulties involved in developing such equipment, most countries, including the United States, don’t yet have it. Germany is the rare exception, it said.
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