Chapter 1529 Cat and Mouse Game

The air in the conference room seemed to freeze.

In fact, this cannot be blamed on the slow reaction of the people in Qiong Province.

First of all, using radar, especially airborne radar, to detect submarines is indeed not a conventional technology.

Secondly, the detection results of the synthetic aperture radar are a series of dark stripes of varying widths, which are completely inconsistent with the characteristics of a ship's wake in any sense.

"Wait a minute, we can't jump to conclusions so hastily..." Chang Haonan's fingers danced on the keyboard, "If we want to retain more characteristics of hydrodynamic waves, we can perform a low-rank sparse decomposition before normalizing the grayscale transformation... I'll send the algorithm principle over, Engineer Yuan, please deal with it immediately."

Although he said so, Zhang Xi could no longer sit still and had already begun to instruct an operator next to him to prepare to contact the fleet in order to report the situation quickly.

And when he raised his head again.

On the screen, the originally blurred stripes have become clear.

It was a huge V-shaped ripple with the tip pointing southwest and two traces about 2.5 kilometers behind it.

"Kelvin waves..." Wang Zhijin's breathing almost stopped, and his voice suddenly became sharp, "The characteristic waves of submarines sailing underwater!"

"And it's very large." Zhang Xi, who is more familiar with the submarine business, added, "Based on the corrugation angle and length... uh... the length should be unreliable. In short, the speed should be below 10 knots, and the displacement should be no less than 3000 tons."

SAR can only detect the characteristics of water waves in shallow waters, and the other party was obviously sailing and diving at the same time, so the actual wake left behind is likely to be much longer than what is shown in the image, but it cannot be detected.

"Hurry, connect to the fleet command!" Zhang Xi stood up, straightened his clothes, and put on his military cap.

Half a minute later, another screen showed the scene of a busy command post.

"Comrade Commander." Zhang Xi saluted and did not bother to be too polite. He reported directly, "While analyzing the results of last night's reconnaissance, we found that an unidentified submarine was sailing southwest near the Luzon Trough and was about to enter the nine-dash line..."

The fleet commander on the screen, who had originally had a kind face, quickly turned into a nuclear-kind face: "Coordinates, and target attributes?"

"Sending the reconnaissance results..." Zhang Xi's forehead was already covered with sweat. "But this intelligence was obtained by the aerial reconnaissance of the WZ-8, so the target attributes cannot be determined for the time being. I suggest sending a destroyer and frigate formation and fixed-wing anti-submarine aircraft to search..."

"..."

After saying this, even Zhang Xi's voice became softer.

This radar image was taken about 10 hours ago. If the target was a nuclear submarine, it should have sailed a hundred nautical miles or more.

Given the complex maritime conditions in the surrounding areas, relying on a few warships and aircraft to search such a large area is like looking for a needle in a haystack in the physical sense.

In fact, this is why in today's highly information-based world, a single nuclear submarine can still play a huge deterrent role.

Unless you control the key waterways, it would be too difficult to find.

Both the fleet and the anti-submarine aircraft are almost insignificant in the face of the vast ocean.

As a result, offensive anti-submarine missions are extremely difficult to carry out, and the only option is to remain vigilant and passively defend at all times.

But at this time, the commander on the screen had finished reading the report and looked up to analyze: "It's not that pessimistic... The depth of the Luzon Trough is more than 2000 meters. There is no need for a nuclear submarine to take the risk of surfacing to such a shallow depth... So this is most likely just a conventional submarine, which temporarily chose a depth of more than ten meters for charging or high-speed navigation."

This conclusion made Zhang Xi, whose face was a little pale, perk up again:

"The US Navy doesn't have conventional submarines, so it's most likely the Soryu class, or... it should be the Soryu class," he quickly concluded. "The AIP system can maintain long-term submergence, but the speed is very slow. If the surrounding threat level is low, it may choose to sail with a snorkel or charge."

South Korea's Sun Won-class also has an AIP system, but its displacement is less than 2000 tons, which does not meet the target characteristics.

Yuan Xiaokang's voice came from the side: "This image was taken about 10 hours ago. Since it has returned to the deep water area, it is calculated at a typical speed of 4 knots..."

"With a semicircular range of 40-50 nautical miles, it is possible to complete the search by relying on the fleet combined with fixed-wing anti-submarine aircraft!" Zhang Xi added.

Just a few minutes later, the combat order was issued:

The Xingcheng, Jiangcheng and Huangshan fleets ended their tracking of the Hyuga and rushed to the relevant sea area at the fastest speed. At the same time, they dispatched two Air-Submarine-200 anti-submarine aircraft to conduct a general search, and the other four were put on standby...

……

But the atmosphere in the meeting room remained solemn.

Because they are facing another problem.

"Most of that area is high seas." Wang Zhijin frowned. "Even if we find it, as long as it doesn't come up on its own initiative, we can't take military measures. The best we can do is scare it."

"But the Dongchao of the Maritime Self-Defense Force suffered a loss a few years ago." Zhang Xi sighed, "I'm afraid it won't be so easy to scare them out again now."

"..."

"I have an idea."

It was not until this moment that everyone remembered that the other video call had not been disconnected.

Chang Haonan narrowed his eyes slightly. "The underwater terrain of the South China Sea is relatively complex, and submarines are highly dependent on multi-beam sonar navigation." He paused. "In theory, if there is a surface ship that can edit sonar waveforms, it can interfere with the results of terrain detection sonar, forcing it to be unable to sail normally and only float to the surface..."

The commander on the screen was stunned for a moment before he understood the situation, but he quickly figured out Chang Haonan's suggestion: "You mean, create a false underwater terrain?"

"That's right." Two people who couldn't see each other were talking in the air. "Of course it can't be very accurate, but as long as the captain feels that there is a trough and a ridge in front of him, he will definitely not dare to move forward rashly."

"Um……"

The idea is good, but the sonars of surface ships are used for submarine detection, and there is no need to design particularly complex waveform editing capabilities.

The cost of this function sounds scary, and it requires master-level technicians to operate it. It has no obvious advantages in submarine search capabilities.

What kind of serious warship would do such a thing?

"Perhaps...Zhu Kezhen?" Zhang Xi suddenly suggested, "The comprehensive survey ship that just completed its modification last month is equipped with a new generation of multi-beam depth sounding system and acoustic signal generator...it may have this function."

The first ship of the Type 636A ocean-going comprehensive survey and measurement ship, although it belongs to the navy, is often used for serious scientific research tasks.

"Ship 872 should be on standby at the port." The fleet commander was of course fully aware of the status of his ships at sea. "According to the plan, they will go out to sea next week to conduct a seabed surface geological survey. If necessary, the mission can be temporarily changed."

Chang Haonan nodded: "If it is confirmed that it has the waveform editing function, then we can create virtual obstacles on the submarine sonar and guide the opponent into the preset area..."

The battle plan quickly took shape.

A few hours later, the 872 ship cast off and set off, escorted by the Taocheng frigate to join the Xingcheng formation. Two C909 platform air-to-air 200 anti-submarine aircraft were operating in rotation, and the Ocean Forecast Center provided real-time hydrological data support...

When the "Zhu Kezhen" left the port, Captain Zhou Yi received a detailed tactical briefing.

This seemingly ordinary scientific research vessel has advanced equipment worth hundreds of millions installed in its acoustic laboratory.

The only problem is that the ship was not designed to carry out combat missions, and the crew had never received combat training.

"We are not going to fight," Zhou Yi said to the crew, "but today's mission may be more important than an actual battle."

……

At the same time, in the deep sea 200 nautical miles away.

The Japanese Maritime Self-Defense Force's Soryu submarine is drifting silently at a speed of 2.5 knots.

Captain Kenji Sato had just ordered the Stirling engine to be shut down in preparation for detecting the surrounding underwater terrain.

"How much power is left?" he asked in a low voice.

Although it has AIP capabilities, the Soryu needs to use multi-beam sonar frequently during this trip, and its battery power is still relatively tight.

"93%, sir." The chief engineer reported, "If we continue to use the Stirling aircraft, we can expect to be able to work for 6-7 days."

Sato nodded.

He needed to plan his route so that he could find a place where he would not be easily discovered to surface and recharge after a week.

Of course, the current focus is still on executing the mission.

"How's the water situation?"

The sonar operator nearby reported in a deep voice, "No surface ship activity has been detected so far."

"Begin terrain mapping."

This secret voyage lasted for more than two weeks, and it was not until last night that it finally successfully entered the mission area.

The limitations of conventional power were fully exposed in this process.

Due to the lower speed limit, only about one-third of a voyage can be used for mission execution.

Fortunately, once entering the mission area, the Soryu, which can be completely silent, will be more concealed than a nuclear submarine.

Kenji Sato has no doubt about the performance of his country's submarines.

He certainly didn't know that a radar image accidentally taken by a high-altitude drone had completely changed the situation of this "cat and mouse game".