Short-wave anti-submarine radar defense circles are arranged within 200 nautical miles of Nanjun Island.

We have to mention "active sonar" and "passive sonar".

Because active sonar constantly sends sound signals outwards, and determines the nature of the target based on the echo. But the consequence of this is that when you detect enemy submarines, you will also inform the enemy submarines of your exact location.

This approach is more of a powerful psychological deterrence.

Generally, in this case, in addition to warning the other party, you also tell the other party that you have been completely surrounded by us and will die if you don’t surrender.

Passive sonar is a passive radar. Because it does not actively transmit signals and only receives sound signals radiated by the target itself, it is not easy to be discovered by the enemy and is mainly used for concealed reconnaissance.

If the contradiction can be used on one thing, then I am afraid that the sonar will be counted.

In modern submarine warfare, 99.99% of the situation can be found when using active sonar. But it also means that you are exposed yourself.

Of course, Han Yi can make "passive active sonar", but there are many things happening recently and I haven't been able to take care of it for a while. How could he know that the other party actually came to the door?

Moreover, under the warning of active sonar, it continued to advance to 100 nautical miles of water, and it seemed that it was ready.

Han Yi's face was gloomy and he wanted to wake up several times to the bottom of the Pacific Ocean.

But this is like poking a hornet's nest.

Submarines that can run to the South Pacific are definitely nuclear submarines. Such countries must have aircraft carriers. Once sunk, it will mean endless troubles.

"What, let me spare your life first."

Then Han Yi ordered: "Send a robot to see which country's submarine it is. In addition, I will issue another warning, and if I don't listen, I will fire the expulsion thunder."

...

Ruby has entered less than 80 nautical miles of sea under the South Pacific Ocean.

At this time, the captain (equivalent to political commissar) Brandon Byron and first mate Tommy Robinson were discussing whether to continue moving forward?

Just ten minutes ago, the active sonar source was found again 30 nautical miles behind the left, which was warning them!

"Tomy, what do you think you should do?"

Tommy Robinson is radical and feels very unwilling to look at Nanjun Island on the navigation map.

After thinking for two minutes, he said: "Keep going. They should have just arranged anti-submarine radars and had no means of attack. But to prevent it, let Simmons and the others prepare for battle."

"..." Brandon Byron was cautious and quickly persuaded him when he heard the battle: "This is absolutely not possible. We just came to investigate and did not receive the order to attack. And you were just guessing that if the other party had an attack weapon, it would be a disaster."

Robinson insisted on his own opinion, "Don't worry about Brandon, as long as we don't take the initiative to attack, he will never dare to attack first..."

"boom--"

"Ouch--"

Before Robinson could finish his words, a violent explosion suddenly occurred in the waters of two nautical miles ahead. The surging undercurrents swung the submarine left and right. Robinson, who was standing in front of the instrument, suddenly fell to the ground.

"Sir, they fired the expulsion thunder...bad, here we are again..."

"boom--"

Two consecutive shots of thunder exploded at the bottom of the water, and the violent currents blew the ruby ​​and swayed, and the crew in the submarine even fell.

"These ***s really dare to attack..." Robinson was so angry that he cursed, "Listen to my orders and fight back immediately."

"Sir..."

Robinson gritted his teeth and said, "Attack!"

"yes!"

"Listen to my command...

Missile preparation...

Target parameter 330xyt209…

Lock the target...

emission……"

"Bang..."

A tremor was emitted from the submarine, and a famous SM-39 "Flying Fish" submarine-launched anti-ship missile launched at a huge humanoid submarine machine 20 nautical miles away with a range of 0.9 Mach.

However, what the people on the submarine did not expect was that the Feiyu missile was intercepted 2 nautical miles away.

Looking down from above the sea, you can find that the sea surface, which was originally calm under the night sky, was already surging waves and white waves were rising and falling;

At this moment, a large chunk suddenly popped up at the center of the wave, and then exploded violently.

"Boom--" The sea water suddenly jumped up ten meters high, and huge waves splashed out dozens of meters away. The center point seemed to have been evaporated, revealing a huge black cave, which was then quickly filled by sea water.

Seeing that the missile was intercepted, Robinson was also shocked and frightened and ordered a full speed retreat.

At the same time, Han Yi also knew the identity of the submarine.

...

"So it's you..."

Han Yi sneered.

The two sides had many rifts in Sagarata. In order for his wife to exploit gold smoothly, he sent 60 million US dollars out, most of which were taken away by French-controlled forces.

Now the other party ran to his doorstep to fire a missile. If they just let them escape, they would be unwilling to accept it.

But it cannot really sink. In that case, the French government will go crazy and will never stop until then.

Soon Han Yi came up with a solution, not to sink the submarine, and at the same time he could blackmail the French government.

"Voiceprint Recording"!

As the most important feature of a submarine, voiceprints, especially those of underwater tactical silent navigation, cannot be collected completely.

The noise of the seabed background is very complicated, and it is quite difficult to search for the sound of submarines inside.

In the past, silent technology was not developed, and the continuous noise of submarines operating normally was easier to hear directly with passive sonar;

After the popularization of modern shock-absorbing rafts, sound-absorbing tiles and large rolling screws, such continuous noise has been greatly reduced. It is difficult to get out of the ocean background noise;

At this time, the voiceprints of specific submarines are naturally needed as the basis for comparison and filtering.

Therefore, once the voiceprint is grasped, the submarine will have no secrets like a little girl undressed.

Before you find someone under the sea, others will find you. At that time, you will sneak a missile to you, and the consequences will be unimaginable.

At this time, in Han Yi's opinion, this ruby ​​was the fat meat delivered to the door.

...

Under the dark and deep ocean, the ruby ​​submarine was retreating at full speed.

Although the island landing mission has not been completed, knowing that the opponent has great power to intercept weapons is considered a great achievement.

If it weren't for the fact that it wasn't completely out of danger at this time, Robinson and all the crew were ready to drink and celebrate.

Unfortunately, Robinson didn't know that at this time a robot was lying outside the submarine, with his palm pressing on the submarine, collecting sound patterns and vibration waves from 0 distance.

Ten minutes later, after collecting the complete voiceprint, the robot actively released his palm.

...

A week later, just as the French government was preparing to request the United Nations to launch a joint investigation into the South County Island in the South Pacific, the Joint Navy Command received an email.

The email address of the French Navy Command is not open to the public and is only used for internal contacts. This external email without identification code appears very abruptly.

After discovering the email, the headquarters office staff first asked the technician to isolate the email and clicked on it after confirming that there was no danger.

The content of the email was: I am a swimmer. A few days ago, I accidentally saw a strange big guy 600 nautical miles east of Fiji Island. Out of curiosity, I recorded the wonderful sound of this big guy with my carry-on equipment.

There is also an attachment at the back of the text. It is about 5mb.

The office staff downloaded the file out of curiosity.

This is an audio file.

"Wow...Wow...Wow...Wow...Wow...Wow...Wow..."

After all the playback was finished, the office staff and technicians looked at each other. They only heard a noisy background sound and nothing else.

Finally, the office staff found his supervisor Smith. The Smith supervisor had a different vision and suddenly realized that this was the submarine's voice pattern. Then, combined with the content of the email, his face changed drastically.

"Quick, copy this audio to me. In addition, this computer is not allowed to be used without my approval."

Soon, the Smith manager hurried to the superior supervisor with the encrypted USB drive.
Chapter completed!