November 2013, Zuaohai
After nearly 30 days of sailing, the submarine that Burhan was on traveled across the ocean and arrived at the planned stopping point 200 nautical miles off Zuao Island, with a diving depth of 60 meters.
The scheduled reporting time has arrived, and the submarine begins to rise to a periscope depth of 20 meters.
Burhan estimated that the translator was taking notes and would soon seal the message in an envelope and hand it over to him for translation.
Sending messages to submarines is the most difficult part of military communications because the submarine is underwater and high-frequency radio waves cannot penetrate seawater.
Electromagnetic waves propagate along straight lines. When encountering an obstacle, if the wavelength is shorter than the obstacle, part of the electromagnetic wave is reflected, part of the electromagnetic wave is incident on the obstacle, and the energy is absorbed.
But when the wavelength is larger than the structural size of the obstacle (such as water molecule clusters), the electromagnetic wave will be able to bypass the structure of the obstacle and continue to propagate forward. This phenomenon is the diffraction of light (also called diffraction).
The longer the wavelength, the stronger the penetrability of electromagnetic waves with lower frequency.
Very low frequency (VLF) 3-30 kilohertz, corresponding to a wavelength of 100-10 kilometers, is the main frequency band for communication with submarines.
This frequency band can penetrate seawater of about 30 meters, and the submarine can receive signals at the periscope depth at the agreed time.
In the 1950s and 1960s, the nuclear submarines used by the Liang Kingdom and the former Heroic Alliance as a secondary strike force had extremely high requirements for concealment, and their positions were also erratic. They were hidden in the depths of the ocean hundreds of meters below the sea surface all year round.
The penetrating power of very low frequency is not enough. Liang and the former Xiong United States are competing to develop extremely low frequency (ELF) 3-30 Hz, which corresponds to a wavelength of 100,000-10,000 kilometers.
This is an extremely complex technology, because in theory, to receive an electromagnetic wave of one wavelength, the receiving antenna must be at least larger than half the wavelength.
The wavelength of extremely low frequencies is too long, and it is not possible for submarines to be equipped with such long antennas.
Clever engineers thought of the Schumann resonance, taking advantage of the Earth's forty thousand kilometers circumference.
Using the earth's ionosphere as part of the receiving antenna, coupled with a variety of complex technologies and equipment such as electronic extension, the problem of receiving extremely low-frequency signals was finally overcome.
Although the technical problems of extremely low-frequency communication have been solved, the fly in the ointment is that the lower the frequency, the less information the radio waves carry per unit time.
VLF can only transmit a few bytes per minute, and ELF transmission is even less efficient.
In addition, for the purpose of encryption, the amount of bytes required for the same vocabulary in military ciphers far exceeds that of civilian transmissions.
Therefore, when coastal bases send reports to submarines, they are as precious as words. Usually there is only one word, such as attack, surface, enter port, etc.
Burhan waited anxiously for the word sent from the Jade Khanate's long-wave transmitter.
As agreed, Professor Mustafa will pay close attention to the typhoon and wave forecast in Zuaohai.
If there is indeed a big wave, the default action time is set at 1 a.m. on November 9, Brown Oak Country time, then the message should be "action". If there is a big wave on the 8th or 10th, the message should be the corresponding date.
If there are no big waves in these three days, in order to ensure the confidentiality of the operation, the planned return flight will be cancelled, and the message will be "return to flight".
In his final instructions to Burhan, Hamid specifically mentioned that submarine reports are not 100% reliable.
Unless he received a specific date of "return" or a change, any other phrase would mean action on November 9. Another advantage of sending a random word is that it is equivalent to an extra layer of encryption.
The translator finally knocked on Burhan's cabin door. After Burhan signed for it, he sent the translator away, locked the cabin door, and couldn't wait to start translating. The message was indeed very short, with only one word:
"Haiyan".
Burhan hurried into the command cabin and said to the captain:
"The plan remains unchanged, the action begins, please!"
The captain nodded and announced the order loudly:
"Dive depth 60, course 45, speed 10 knots."
Five hours later, in the dark night, the submarine came up to recharge. At the same time, the communication buoy was released and the receiving frequency band was adjusted to the broadcast signal of the Voice of Brown Oak Radio Station.
The monitor compiled the broadcast contents into a briefing and sent it to Burhan. Burhan paid attention to several of them:
1. Comet Ison (C/2012 S1) will cross the ecliptic plane on November 9, its brightness is gradually increasing, and it will reach perihelion on November 28.
The comet is so close to the sun that it is rarely seen in a hundred years. If it is not torn apart by the sun's gravity, it will become one of the brightest comets in history after it turns out from perihelion.
Astronomy enthusiasts around the world are waiting eagerly.
2. On October 29, the sun erupted with an X-class flare. It was the fourth X-class flare within a week, which is extremely rare.
On November 2, a large coronal hole formed on the surface of the sun, and a solar storm hit the earth starting on the 4th.
3. On November 4, a tropical storm gathered in the western Pacific. The National Meteorological Administration named it "Haiyan". It was subsequently upgraded to a super typhoon. It reached its peak intensity on the evening of November 7, making it the strongest since 1979. typhoon.
Typhoon "Haiyan" made landfall on Jiaodo Island on the morning of November 8, causing huge damage and casualties. The number of casualties is expected to exceed 10,000.
Affected by this typhoon, there will be strong winds and huge waves above level 10 on November 9 near Zuao Island. Marine activities will be stopped and all ships will enter the port.
On November 9, 2013, at midnight Brown Oak Country time, the submarine arrived at the predetermined sea area. It could not get any closer, otherwise there was a risk of being discovered or even running aground on the rocks.
When the submarine floats to the periscope height, even under 20 meters of water, it can still feel the huge swell.
Burhan put on his diving suit, checked the oxygen tank, and got into the small cabin of the submarine with another companion.
In 1940, the Mediterranean Navy began to use human-operated torpedoes to attack the Mediterranean Navy. This kind of human-operated torpedo is actually a manually operated underwater mine device.
After several attempts without success, in December 1941, two main battleships of the Navy of Country B were bombed and sunk in the military port.
The Navy of the Fusheng Kingdom subsequently obtained the technical data of the Earthsea Kingdom and completely transformed the man-operated torpedo into a suicide attack weapon.
At the end of the Pacific War, it caused heavy losses and psychological impact on the Liang army.
The Jade Khanate's manned torpedo is a manned miniature underwater working platform, named "Sturgeon".
The "Sturgeon" Burhan was riding on slipped out of the submarine's special loading container and silently headed towards the predicted shipwreck site.
The heavy cruiser Rocket City sank very close to the land of Zuao Island. The seabed shoal is gentle and less than 20 meters from the sea surface. Ocean currents have minimal impact on it, and the displacement has been very small for decades.
Burhan and his companions quickly found the target. The operator and his companions raised the submersible to the surface, and Burhan opened the top cover of his safety cabin.
Strong winds and huge waves instantly filled Burhan's circular cabin with seawater. Burhan opened the oxygen tank valve and swam toward the target. The submarine followed closely behind him while diving.
Burhan's target was the sailor's rest cabin located on the third floor below the deck of the sunken ship. There was darkness in the broken hull, and even under the strong light of the diving helmet, the vision was still blurry.
Burhan swam in and out along the layers of steel plates torn longitudinally by the bomb, searching hard. The Rocket City, with a displacement of 10,000 tons, was too huge for Burhan.
As time passed by, Burhan's physical strength decreased significantly.
He once again entered the depths of the wreckage, completely unable to tell which layer or area it was. Burhan thought silently in his heart:
"Where is it? There is not much oxygen left. Let me find the metronome quickly."
Burhan's helmet light inadvertently swept across a half-meter-long crack, and an object below caught his attention.
Aim the beam, identify it carefully, and vaguely see a metal scale on the object.
"Finally found you!" Burhan felt the heat in his body rush to his head. He calmed down and found that the crack was too narrow for him to swim through.
Burhan searched around the area and finally found a hole of more than 40 centimeters. He tried, but his bloated body with an oxygen bottle strapped to it could not pass through the narrow hole.
"We must complete the mission!" Burhan made a crazy move. He untied the oxygen bottle strap and tied it to the pillar next to it.
He took out a mechanical underwater rebreather from his waist bag, took off his oxygen helmet, held the respirator in his mouth, swam in through the small hole, grabbed the metronome, put it in his waist bag, and swam back to the hole with difficulty.
The respirator in his mouth was not designed for such high water pressure conditions. The moment Burhan came back from the hole, he involuntarily took in a large mouthful of sea water.
He desperately grabbed the oxygen mask, used his last strength to untie the oxygen bottle, and dragged it upward toward the sea.
The companions pulled the dying Burhan back to the submarine, and the doctor performed emergency rescue. Mucus and blood kept pouring out of Burhan's mouth and nose.
Burhan opened his eyes with difficulty, pointed to his waist and abdomen and gestured to the captain. The captain said: "I have locked my pocket bag in the safe, don't worry."
Burhan smiled happily and gradually became silent.
The submarine returned quickly. On the way, Typhoon Haiyan subsided and its energy returned to the sea.
But it firmly believes that the successors will one day unite and rise again.
Between the sea and the sky, on the vast ocean, dancing like a petrel.
On November 28, telescopes around the world failed to observe Comet Ison turning back from perihelion, and thousands of astronomy enthusiasts failed to appreciate the brilliant light of the "Comet of the Century."
Because it, fixed on November 27, has merged with the sun.
