Deep in the Pacific Ocean, in the dark water, a huge silent shadow walks slowly.
This is a strategic missile nuclear submarine belonging to China. It has left port for more than two months and has been diving deep in the ocean. The submariners are isolated from the world, as if everything in the world has nothing to do with them.
The sonar soldier had large headphones on his head and was staring at the monotonous waveform on the screen, making his eyelids twitch.
Half asleep and half awake, I suddenly heard a faint noise in my ears. The sonar soldier jumped up like an electric shock, and listened with wide eyes.
The noise is very weak, but very clear, and various information about the sound source is also given on the screen.
"What's going on?" The captain discovered something unusual about the sonar soldier.
"Report, an unknown sound source was found, port side 22 degrees, distance 62 kilometers, target movement echo is stable...it seems to be an American nuclear submarine." The sonar soldier's voice became smaller and smaller.
The captain raised his eyebrows: "62 kilometers, are you talking nonsense to me?"
There are many factors that affect the effective range of sonar. The most important factors are hydrological conditions and sound source intensity. If the sound source noise is lower than the ocean background, a submarine's passive sonar can only hear for more than 20 kilometers, and active sonar can cover about 40 kilometers.
kilometer.
Not to mention that the active sonar on the boat was not turned on. Even if it was turned on, the noise from more than 70 kilometers away could not be heard. How could it be considered a towed array?
The sonar soldier was aggrieved: "It's really 72 kilometers... There is another one, 19 degrees to starboard, 54 kilometers away... Captain, this one is clearer than the one just now!"
"How is that possible?" The captain took the headphones and put them on his head. Sure enough, he heard a clear noise. He couldn't help but be startled.
The sonar soldier whispered: "Maybe it's going at full speed."
"You tell me!" The captain glared at the sonar soldier, but he couldn't figure out why the two submarines suddenly went crazy.
"Report!" the signal soldier suddenly shouted, "Headquarters order: South, full speed."
The captain frowned: "What kind of nonsense is this?"
"I haven't received the rest yet," the signal soldier said.
Submarines deep in the ocean can only receive long-wave communications. The frequency of long-wave is low and the amount of information carried is small. It takes less than half an hour to receive a telegram.
The captain ordered without hesitation: "Adjust the direction immediately, go south, at full speed!"
With an order, the submarine hidden in the depths of the ocean turned south at a top speed of thirty knots per hour.
Generally speaking, the headquarters should give a signal to the submarine. After the submarine surfaces, it uses a high-frequency radio to exchange data with the headquarters. However, today is different from the past. There is no surface signal at all.
During the voyage, the submarine continued to receive messages from the headquarters, and gradually pieced together the truth of the incident.
It was only then that the captain learned about the alien landing from Antarctica, and finally understood why the headquarters did not give a signal to surface - the submarine's surface speed was only 24 knots, and it had to dive underwater to reach 30 knots.
The purpose of floating up is to grab these six knots of speed!
Not only the submarines in the depths of the ocean received the order, but all submarine bases also received the order to sail immediately. Except for those that were unable to move on the slipway, there were only one remaining submarine that could be launched into the water.
They all ran to the Antarctic with all their might.
Countries are dispatching more than just submarines, aircraft carriers, amphibious landing ships, destroyers, and frigates... As long as all naval vessels with anti-submarine capabilities are deployed and all kinds of anti-submarine equipment are deployed, a large invisible net is gradually taking shape.
The navy never expected that the surface fleet would one day fight against the alien fleet, which is really shocking.
However, the first ones to intervene are still satellites in the sky, which use pairs of sharp electronic eyes to peer into the ocean and look for traces of alien warships.
At the beginning, satellites indeed discovered the whereabouts of many alien warships, but as time went by, more and more alien warships disappeared into the depths of the ocean.
Satellites can only detect targets on the water surface and shallow seas. Once the target dives into the dark deep sea, the satellite will lose its target.
All in all, all human countries have tried their best to uncover the alien warships that have sneaked into the ocean.
The first to arrive near the Antarctic was a US military destroyer. The warship immediately released its towed sonar to monitor abnormal underwater noises.
The listening range of this thing can reach hundreds of kilometers, which is much more effective than submarine sonar. However, the alien warship was not found, but it turned over several submarines that were rushing at full speed... The noise they made was really too loud.
Submarine noise is nothing, what’s even more troublesome is that no one knows the noise characteristics of alien warships!
There are all kinds of strange sounds in the ocean. When sonar works normally, it first filters out these messy sounds and only listens for suspicious sounds.
But without noise characteristics, the filter becomes a decoration, and the sounds most likely to belong to alien battleships must be picked out from the cluttered ocean background.
This matter is not easy to say, but it is not difficult to say that it is difficult. Fortunately, the Navy has no shortage of talents in this field.
The process of establishing space fleets in various countries is very different, and too many talents have been taken away from the navy. However, the space fleet only uses radar and not sonar, so most of the sonar talents remain in the navy.
Moreover, various countries do not search blindly. They also input the appearance of alien warships into supercomputers, and use the supercomputer to calculate what kind of noise the alien warships will produce when sailing in the water, providing a basis for fleets to search for enemy ships.
However, the towed array found nothing, and the captain realized that he had fallen into a misunderstanding and applied the usual anti-submarine procedures to the alien warship.
After realizing this, he immediately changed his tactics, retracted the towed sonar, and turned on active sonar to find the enemy.
The huge flapping sound spread far under the water, and various echoes filled the sonar soldier's eardrums, but nothing useful was heard.
The captain believes that such a large alien spacecraft does not comply with fluid mechanics, and the noise it generates must be very obvious, but now there is no discovery at all. Either the enemy ship has not entered the sea area, or the enemy ship has sunk to the bottom of the sea.
Sonar doesn't work at all.
The top brass of the U.S. military strongly agreed with this opinion and immediately took corresponding actions.
After a while, an anti-aircraft ship entered the search area and released twelve "torpedoes" underwater.
This is a submersible robot used to search the seabed. It can work for four to six hours on the seabed where the sun never shines all year round. If an alien warship really sinks to the bottom of the sea, these robots are the most suitable equipment for searching for enemy ships.
Not long after the robot launched into the water, sonar suddenly discovered a group of special targets underwater that were very fast and moving in the same direction.
They rise from the bottom of the sea at extremely high speeds and quickly approach the water surface.
