Tell me about submarine communications, such as long wave communications

At present, the radio communication used by shore (base) to submarine (boat) is generally ultra-long wave (i.e., very low frequency VLF radio communication) and very long wave (i.e., very low frequency ELF radio communication), because its loss in the water medium is small, the maximum penetration depth of ultra-long wave (frequency 3 30 kHz) with a wavelength of 10-100 km is about 30 meters, and the maximum penetration depth of extremely long wave (frequency 3 Hz-30 Hz) with a wavelength greater than 10,000-100,000 km is about 200 meters. Therefore, the submarine can receive the long wave without releasing a communication buoy, and it is effective to receive it at a depth of 20-100 meters by using its own receiving device or towing antenna. Note: Only one-way broadcast communication, i.e., shore-to-submarine transmission commands, can be satisfied here.

In principle, submarines should emit as few or no radio waves as possible, and if they must emit them, they should also try to shorten the communication time and increase the information transmission rate, and the total time for transmitting radio waves in the air is limited to the reaction time of the radio reconnaissance and positioning system, such as the time to complete a communication, which makes the enemy's positioning system too late to react to the presence of radio wave signals.

This issue is addressed in Article 1. In addition, relay methods are often used, such as airborne or ship-based relay stations, which have expanded the distance and depth of communication.

The United States has a "deep alert" plan, which simply means that when the submarine takes the initiative to contact the shore base, it will release a communication buoy, and then, according to the pre-set procedure, the buoy will first stay underwater for a period of time after leaving the mother boat. When the submarine reaches a safe distance, it slowly surfaces, and with the help of communication satellites, it sends a code signal to the shore base, and establishes contact with the latter, and the buoy will extend an antenna under the water, encode and encrypt the information from the shore base, and then convert it into an acoustic pulse and send it to the submarine within 50 square nautical miles (about 171 square kilometers).

1. Why do the major powers build long-wave communication stations at any cost, in the past, for this problem, Maozi even turned his face with rabbits.

The characteristic of long-wave communication is that it has a certain underwater penetration ability, which can allow submarines about 30 meters underwater to receive the latest information sent from the shore, compared with other short-wave and medium-wave communications.

However, due to the instability of the atmospheric environment and ocean currents, signal failure is prone to occur during signal transmission, so the nuclear submarine will adopt the method of floating and releasing communication buoys in order to enhance the reception of signals far away from the transmitting station to ensure the stability of signal reception.

2. The submarine itself is subject to volume limitations, and it is impossible to install long-wave communication equipment. Under normal circumstances, the reconnaissance department will use the three-point positioning method for positioning, and if the transmission time is short and the signal strength is weak, it is still possible that it will not be detected.

3. The long-wave radio can only be accepted under water about 30 meters, and it cannot be heard no matter how deep it is.

Due to the large size of the long-wave radio transmission system, it is difficult to protect, such as Lao Mei, Maozi, etc., a large number of special communication aircraft are used as a replacement, and the aircraft releases the transmitting antenna from the tail when flying, and then sends the corresponding signal.

Submarines mostly receive information passively underwater, and rarely interact with the ground (actively sending long-wave communications is dangerous for submarines).

Submarines must navigate underwater during wartime and cannot obtain war intelligence in a timely manner, so they must rely on communications to ensure the command of their underwater operations and other tactical activities. Due to the presence of a certain conductive medium in seawater, it is difficult for traditional radio waves to penetrate seawater for submarine communication, which has caused certain difficulties for submarine communication.

Modern countries generally use long-wave ultra-long-wave anti-submarine communication systems, and long-wave ultra-long-wave communication is a kind of radio wave that operates in the low-frequency band. Its attenuation in seawater is smaller than that of other frequency bands, and it can penetrate seawater for propagation, and the propagation depth can reach 100m, and the propagation channel is stable, which basically meets the requirements of submarine communication in deep water.

However, there are also outstanding problems: it requires a huge transmitting antenna or ultra-high transmitting power when transmitting, which makes the transmitting equipment extremely vulnerable to enemy strikes; In addition, the transmission frequency band is narrow, and can only communicate with the shore base in one direction, but not two-way communication; In addition, the concealment is poor, the underwater transmission rate is low, and the submarine mainly relies on the surface to receive information, which reduces the concealment of the submarine and increases the danger factor of the submarine.

Although long-wave communication has such and such shortcomings, it is indeed the most used method at present. In the early years, China even tore its face with the Soviet Union, the big brother of the year, because of the construction of long-wave radio stations, which was called the fuse of the rupture between China and the Soviet Union. But it can be seen that the long-wave radio station was indeed the only ideal way for submarines to communicate underwater at that time.

Directly surfacing through long-wave radio or satellite communication, you can also release the pontoon to stretch the antenna out of the water, because the efficiency of electromagnetic waves propagating in the water is very poor, and surfacing refers to extending the antenna, at this time the submarine is not out of the water, but the diving depth is very small, and it is easy to be detected by anti-submarine aircraft. In addition, during World War II, there were also submarines that used torpedo launchers to launch pontoons to send carrier pigeons out to the sea to transmit information.

Radio ultra-long-wave signals or very long-wave signals.

Under water, there is no contact between submarines and submarines. The main contact with the submarine is with the base or a unit similar to a ** station. If the submarines must communicate with each other, they will also receive them in one direction through a station similar to the ground **.

In other words, the submarine only receives instructions from the outside world and does not take the initiative to send reports. Except, of course, for the U571, the unlucky submarine that arrived at home.

During World War II, when a submarine was in contact with a submarine (the outside world), it was necessary to bring the submarine to the surface in order to communicate by radio. But floating and using radio to communicate would make the submarine lose its hidden meaning, and it would also be easy to be detected by surface ships and aircraft. To solve this problem, modern submarines can use buoy antennas or buoyancy antennas, that is, the antennas are applied to the surface through a long rope, so that the submarine can also transmit signals underwater.

In fact, there is still a problem of self-exposure of submarines, because submarines use short-wave communication at long distances, and their signals themselves are not secret, and they may be intercepted and deciphered by the enemy, and the position of the submarine can be measured, and the buoy antenna exposed to the water may also be detected by enemy radar. Therefore, even if a nuclear submarine does not deploy a communication buoy underwater, it will not be able to actively communicate with the outside world. Moreover, even if the instructions to the submarine were to be given, they could only send some pre-defined and easy-to-understand signals.

However, with the development of laser technology, now the military powers are turning their attention to satellite-to-submarine laser communication. Lasers are electromagnetic waves with a frequency band of more than 10 kilohertz (wavelength 3-30 microns) at very high frequencies and send or reflect information to submarines through satellites. The transmission rate of laser communication is fast, hundreds of thousands of times faster than that of extremely long-wave systems, and it has the characteristics of good directionality, high brightness, energy concentration, strong confidentiality and strong anti-nuclear destructive ability.

Laser communication equipment can be made light and economical, especially the antenna is small, the general antenna is only a few tens of centimeters, and the weight is only a few thousand grams. These characteristics of laser communication can enable the submarine to complete the communication task in the best safe cruising state underwater. But in general, whether it is with buoy antennas or buoyancy antennas or laser communications, submarines are still mainly used to receive communications.

2.The submarine that sails generally refers to the nautical chart, so the route must be very accurate, I need to work in the submarine for a period of time because of the work, here I will tell you how the submarine sails. Submarines generally sail at the periscope height, do not turn on active sonar only passive sonar, the power will not be fully turned on when sailing, the average speed is about 12 with 18 knots, this state submarine has a radar stretched to the sea surface, and the ship navigation is similar, there is a kind of navigation called submarine, before diving, there are special officers to calculate the direction of sea water flow speed, and confirm their position in the ocean in detail, draw on the chart, and then the submarine begins to tilt, and do not let the toilet be used when divingMany people were busy during the dive, and the inside of the boat began to be controlled to prevent people from moving.

When snorkeling, it feels very stuffy, and people are prone to fart. Take care of me and give me an oxygen cylinder to use from time to time. And the speed is significantly faster, I heard that it can reach 25 knots at the earliest.

The position of the submarine during the voyage and the route are calculated by computers and experienced officers. Make a mathematical model, go up to see if the route is right after n days, and then dive down, there are people in it who only wear pants, and it is estimated that no one manages it, many passages are turned on every time, and most of the rooms are not allowed to move, too boring. I don't want to go in anymore when I come out of it, and the environment is not something that ordinary people can enjoy.

1. Yes, you can only use long-wave radios, and submarines can only receive long-wave signals from land, and they can't transmit them underwater.

2. Even if it is a long-wave signal, it is not absolutely reliable, mainly affected by the depth of the water, generally below 50 meters underwater, the signal begins to seriously attenuate, and when it is below 100 meters, it is basically impossible to accept any signal. In addition, the climate, ocean currents, reefs on the bottom of the sea, and the location of satellites will affect the quality of the signal to some extent.

Therefore, the communication problem of submarines is still a thorny problem after all, and submarines cannot keep in touch with the base anytime and anywhere like surface ships. It is not uncommon for nuclear submarines to lose contact with their bases after they go to sea.

There are mainly short-wave, ultra-short-wave transceivers, very long-wave receivers, satellite communications and underwater acoustic communication equipment. Submarines mainly use short-wave communications to report to shore command posts, very long-wave receivers are mainly used to receive telecommunications from shore command posts, and ultra-short-wave communications are mainly used to carry out short-range communication with other ships, aircraft, or coastal communications. Submarines can use a lifting antenna to receive information at a certain depth, and if a towed antenna is used, it can receive information at a larger depth.

Satellite communication can enable the submarine to communicate with the shore command post through satellites, and the communication distance is long. Underwater acoustic communication, which is used for underwater communication and identification with other submarines and surface ships. In order to ensure the concealment of communication, submarines generally adopt a one-way communication mode and use an ultra-fast communication system, which can enable the submarine to send a message to the shore command post in a very short instant.

Underwater Acoustic Countermeasure Equipment Mainly includes reconnaissance sonar and underwater acoustic jamming equipment. Reconnaissance sonar, which is used to reconnoiter the acoustic information emitted by the active sonar of the target and its technical parameters. Underwater acoustic jamming equipment mainly includes underwater acoustic jammers, underwater acoustic decoys (submarine simulators) and air curtain bombs, which are used to suppress, confuse, and decoy the enemy's sonar tracking or acoustic self-guided torpedo attacks.

There is cable and radio in the boat, and radio is used outside the boat to relay through satellites.