The Pentagon experts were right.

The humpback whale wanted to return to Nakaun City, so it naturally traveled south along the African continent and finally passed through the side of Madagascar.

However on both sides of the island of Madagascar.

Two Burke-class missile destroyers, four frigates, have been lined up in battle formation in the sea area on both sides at once.

Each blockade line is centered on Burke-class missile destroyers, two frigates are responsible for dropping sonar buoys, and the Burke-class has released the SQR-20 active and passive towed sonar system.

In their naval formations, there are no specialized anti-submarine ships.

At present, the functions of warships are all modular and diversified, and according to the tactical equipment carried by each warship, the sea, land and air networks are carried out to form an unbreakable antisubmarine network.

Sky Force, are two P-8 anti-submarine patrol aircraft.

However, the commander of the Combined Fleet, Lasit, thought that the submarine of Behemoth Industries would have to travel for at least three to four days before it could sail from the seaside port of Nicaya.

Therefore, they only began to arrange sonar detection equipment in advance, and the day after tomorrow, anti-submarine patrol aircraft will arrive here to carry out patrols.

There are no anti-submarine patrol aircraft, they also have anti-submarine helicopters.

Whether it is a missile destroyer or a frigate, it is possible to carry a military helicopter on a mission. This time, they all took anti-submarine helicopters with them without exception.

"Puff~", "Puff~", "Puff~"......

The orange-red buoys, which look like fire extinguishers, are projected into the sea by helicopters or frigates at a predetermined distance.

These orange-red buoys are cylinder-shaped like fire extinguishers, and they fall into the sea and splash insignificant waves.

The sonar buoy floats in the water in an upright position, and the excitation device detects the presence of seawater, and immediately ejects the sonar base array into the shell, and connects it with a cable, allowing it to slowly sink to a predetermined working depth under the action of gravity.

At the same time, the sonar buoy also sank into the water, and only a small palm-sized fan-shaped signal receiving antenna protruded from the surface of the sea.

The sonar buoy is the "big net" of this [whaling operation].

These sonar buoys have a detection range of about 15 kilometers, and the fleets on both sides of the island of Madagascar have densely dropped more than 300 sonar signal buoys in this area.

They form an impermeable web of detection underwater, quietly waiting for the arrival of the submarine of Behemoth Industries.

By evening, all sonar buoys were deployed.

In the combat command rooms of the two Burke-class missile destroyers, on the electronic charts representing their mission areas, a red signal node was lit up in every corner.

These nodes transmit their collected sonar information to the command ship at a frequency of two seconds.

The signal is transmitted through the sonar buoy's own short-range radio transmitters, which emit high-frequency digital signals. The channel capacity is large, but the penetration is poor, and the signal attenuation is serious.

The signal only travels within the mission area and is equipped with a corresponding receiving antenna to prevent the signal from being detected by the outside world.

Four hundred sonar signal buoys, which relay information every two seconds.

And this is one of the shipping lanes of the African continent, so the sonar buoy quickly scans for multiple [mechanical sound sources] and triangulates the exact location of those sound sources through the time of the sound sources detected by the adjacent sonar buoys.

The trajectory of the giant ship appeared on a huge electronic warfare chart.

Modern sonar technology has been completely electronic and informatized.

Like in a naval war movie, the sonar monitor sits in an airtight soundproof room, all listening to the sound with headphones. It cannot be said that it is completely in the past tense, but it certainly does not appear at a moment when the approximate location of the target has not been confirmed.

At this time, in the combat command room, the sonar personnel in charge of sonar information were taking a sip of coffee from time to time and debugging the equipment leisurely.

The sonar listens to all the sounds in the ocean.

Whether it's the waves, whales, dolphins, schools of fish, and human-made boats of all sizes, they all make their own unique sounds in the sea.

Among them, the sound of human-made ships is the most regular.

The sound of the propeller spinning and hitting the water, the sound of the cylinders of the large engine hitting back and forth.

These myriad sounds come together and are then transmitted by sonar to the mothership, and there is no need to think of a distinction at all. A dedicated information processor will automatically match these sound sources to the information in the voiceprint library.

The sounds of marine life and the waves are filtered, and the sounds of human-made mechanical motion are labeled in detail.

Other than that~

These sonar-marked ships will also be scanned by the advanced shipborne radar on the frigates and destroyers.

Radar can detect the contour and speed of the ship, and civilian ships are fundamentally different from military ships in terms of mechanical power mode and shape speed.

Therefore, the hundreds of kilometers of sea on both sides of Madagascar Island are all in the hands of the warships of the [Whaling Operation].

……

The commander of the Combined Fleet, Lassett, sits aboard a Burke-class guided missile destroyer in the waters to the south.

Although the previous meeting estimated that the submarine of Behemoth Industries only had a 10% chance of going this way. But Lasitt felt that the 10 percent was likely to surprise him.

Radio silence does not mean that all ships have disappeared from the vast sea.

Modern warfare is all information warfare, and losing contact with the headquarters is not the same as fighting alone?

Radio is not available, they also have satellite data links.

Satellites in space send a steady stream of data to the vast ocean. Warships that practice radio silence can passively receive information from the headquarters through satellite receivers.

Passive reception cannot be detected.

Lassite had received the latest satellite photos of the port from headquarters, and the strange submarine with a swarthy body had disappeared.

It's noon, and in another three or four days, the submarine will be headlong into the encirclement.

Lasitt felt that there was plenty of time to take advantage of these few days of rare leisure to rest.

After explaining the duty task, as soon as Lasit stepped out of the watertight door of the headquarters with his front foot, someone inside shouted: "Wait~ sir." ”

Lacit moved back and glared at the sonar man who had stopped him.

"Sir......

The sonar man squirmed to his feet, "Our shipborne passive sonar has detected anomalous voiceprints. ”

"How unusual?" said Lacit, a little displeased.

It is common for sonar to detect anomalous voiceprints, especially with a large sonar pedestal installed under the bow of a destroyer, which can even collect anomalous voiceprints in an area of thousands of square kilometers if the destroyer is stationary.

The premise is that this voiceprint is particularly large and can travel very far.

"Very special. The sonarman's eyes only dared to stare at the screen, "Sir, we have never recorded this voiceprint, not even seen it. ”

"It'...... It feels like a supercar running wild on the sea. ”

"Are you sure?"

"OK ......"

Lacit stepped forward quickly, "What is the distance of the anomalous voiceprint?"

"Between 500 and 700 nautical miles. At the same time as the sonar officer reported, he also handed out the monitoring headphones to Lasit.

The detection distance and detection accuracy of sonar have always been a technical contradiction between the two.

The large sonar installed under the destroyer can detect abnormal voiceprints in the far sea, but it cannot use the voiceprints to locate the specific location of the sound source, and even the direction can only be vaguely obtained.

The sonar buoys that are dropped into the surrounding sea area for hundreds of kilometers have a very short detection range, but the detection accuracy is higher than that of radar.

In addition, it also has the function of capturing voiceprints.

Lassie put on her headphones.

Then he heard the anomalous voiceprint that had been filtered through the processor.

It is almost impossible for anyone who is not professionally trained to hear what is abnormal in this voiceprint clip that is specially marked as "abnormal" by the processor.

Ordinary people listened to it, and there was only a sound like "zizi woo~" similar to electricity.

But Lasitt was trained professionally, and even if he didn't train for a long time, he was able to pick up anomalies in these electrically like sounds.

It was a very high-frequency, repetitive mechanical sound.

The sonar man was right, it sounded very similar to the roaring engine of a supercar.

But!

But if the target is a speedboat with a professional high-speed engine, it is being piloted by a wealthy man.

It is impossible for it to travel a distance of several hundred nautical miles underwater.

The hull structure determines its engine power, propeller size.

The smaller the power and size, the smaller the sound source will naturally spread.

Unless......

Unless the target is an ocean-going giant ship of more than 10,000 tons.

Isn't it a joke that a giant ship of more than 10,000 tons has the sound of rapid reciprocating movements of the engine that can only be found in supercars?