So far, sound waves are the only form of energy that can be transmitted over long distances in the deep sea. So the technology for detecting underwater targets - sonar technology came into being.
The so-called sonar (sonar), the abbreviation of sound navigation and ranging, uses the physical characteristics of high propagation speed and low attenuation of sound waves in water to search, locate, identify and track targets in the water. The technical equipment is known as the underwater "clairvoyance" and "wind ear". During World War II, the British destroyer "Walker" used sonar to detect the position of the German submarine "U-99" and sank it to the bottom of the sea.
The world's first sonar was invented in 1971 by French physicist Langevin. Sonar works on the echo sounding method (similar to radar). Sonar is divided into passive sonar (or noise sonar) and active sonar according to its working mode. Today's sonar has both of the above. Take passive sonar as an example: when the target moves in the water or on the water surface, mechanical vibration and noise will be generated, which will be transmitted to the sonar transducer through the seawater medium. The transducer will convert the sound waves into electrical signals and then transmit them to the receiver. After amplification, it is transmitted to the display console for display and audiometric orientation. Passive sonar has good concealment and strong ability to identify targets, but it cannot detect stationary targets. Active sonar can solve this problem, but active sonar easily exposes itself and has a short detection range.
Initially, sonar was mainly used to detect enemy submarines. With the development of technology, sonar has developed to the fifth generation, that is, digital sonar, and its performance has been greatly improved. In addition to being used in the military for searching submarines, detecting mines, seabed warning, underwater navigation, underwater (torpedoes, mines, etc.) guidance and confrontation, it is also used for marine resource detection, research and development, such as detecting fish and shrimp swarms, detecting The depth of the ocean, submarine reefs, shipwrecks, oil pipelines, submarine cables and underwater obstacles, as well as submarine oil and gas, etc.
Sonar
Sound waves are an important means of observation and measurement. Interestingly, the English word "sound" as a noun means "sound", and as a verb it means "detection". This shows the close relationship between sound and detection.
When observing and measuring in water, only sound waves are unique. This is because the operating range of other detection methods is very short, and the penetrating ability of light in water is very limited. Even in the clearest seawater, people can only see objects within ten to tens of meters; electromagnetic waves in water are also The attenuation is too fast, and the shorter the wavelength, the greater the loss. Even if high-power low-frequency electromagnetic waves are used, they can only propagate tens of meters. However, the attenuation of sound waves propagating in water is much smaller. If a bomb of several kilograms is exploded in the deep-sea sound channel, the signal can still be received 20,000 kilometers away. Low-frequency sound waves can also penetrate several kilometers of strata on the seabed. And get the information in the formation. For measurement and observation in water, no more effective means than sound waves have been found so far.
Sonar is a device that uses sound waves to detect and locate underwater targets. It is the most widely used and important device in hydroacoustics. It is the translation of "SONAR", which is the abbreviation of Sound Navigation and Ranging.
Sonar is divided into active sonar and passive sonar. Active sonar evolved from a simple echo detection instrument. It actively emits ultrasonic waves and then collects the echoes for calculation. It is suitable for detecting icebergs, reefs, sunken ships, sea depths, fish schools, mines and hidden submarines with their engines turned off. ; Passive sonar evolved from simple hydrophones. It listens to the noise emitted by the target and determines the target's location and certain characteristics. It is especially suitable for submarines that cannot make sounds to expose themselves but need to detect the activities of enemy ships.
The transducer is an important device in sonar. It is a device that converts acoustic energy into other forms of energy such as mechanical energy, electrical energy, magnetic energy, etc. It has two purposes: one is to emit sound waves underwater, called a "transmitting transducer", which is equivalent to a speaker in the air; the other is to receive sound waves underwater, called a "receiving transducer", which is equivalent to a speaker in the air Microphone (commonly known as "microphone" or "microphone") in . In actual use, transducers are often used to transmit and receive sound waves at the same time. Transducers specifically used for receiving are also called "hydrophones". The working principle of the transducer is to utilize the piezoelectric effect or magnetostrictive effect of certain materials that expand and contract under the action of an electric field or a magnetic field.
Like many scientific and technological developments, social needs and scientific and technological progress have promoted the development of sonar technology.
The "Ice Sea Shipwreck" event prompted the birth of the echo sounder. On April 14, 1912, the British luxury liner "Titanic" sank after colliding with an iceberg in the North Atlantic on its maiden voyage to the United States. This largest maritime accident in history caused a great shock and prompted scientists to study Detection and positioning of icebergs. British scientist L. F. Richardson applied for two patents five days and one month after the ship sank, using sound waves to detect obstacles in the air and water, and proposed the use of directional transmitting transducers, but he did not continue to work on it. His patent. In 1913, American scientist R.A. Fessenden applied for multiple patents for underwater detection and built the first echo detector using a moving coil transducer of his own design. In April 1914, he used this equipment to successfully detect icebergs 2 nautical miles (3.7 kilometers) away by emitting 500-1000Hz sound waves.
Following this, in 1914, the first The outbreak of the World War greatly promoted the development of hydroacoustic positioning and directional weapons. During World War I, German submarines were active and launched "infinite submarine warfare". The Allies and other countries were very annoyed and began to develop hydroacoustic equipment to detect underwater submarines. Many famous scientists participated in this work. A young Russian electrical engineer, C. Shilovsky, started developing hydroacoustic detection equipment very early under the influence of shipwrecks on the ice. After the start of World War I, he recuperated in the mountains of Switzerland and felt that he was very interested in anti-submarine warfare. After gaining importance, he turned his research to the use of high-frequency sound waves for submarine echo detection. His suggestion was adopted by the French government in February 1915 and handed over to the famous French physicist Lange. Professor Langevin was responsible for the implementation. Langevin and Shilovsky decided to use high-frequency ultrasound. They used mica electrostatic transducers, placed mica sheets in two electrodes, and applied alternating voltage to emit sound waves. , using carbon particle microphones as receiving transducers, using such crude equipment, successful propagation experiments were carried out on both sides of the Seine River at the end of 1915 and early 1916. They achieved two kilometers of one-way propagation and received reflected signals from the seabed and The reflected signal from a steel plate 200m away. News of their success spread to the UK, which also set up a team to develop an echo detector.
In order to increase the detection distance, it is necessary to increase the intensity of the emission and the sensitivity of the reception. , they used the piezoelectric effect discovered between 1880 and 1881 to generate and receive ultrasonic waves, but the piezoelectric effect was still very weak. By coincidence, a high-power tube high-frequency amplifier was invented in the field of electronics at that time, which was used to amplify voltage. The remaining problem was to find a quartz single crystal with a piezoelectric effect. In November 1917, Langevin finally persuaded an optician to donate a piece of quartz with a diameter of about 10 inches that he had collected for many years. Single crystal exhibits, wafers were cut out of them to make quartz piezoelectric receiving transducers, coupled with mica electrostatic transmitting transducers, to complete a 6km one-way signal transmission and reception. Later, quartz was used to replace mica to complete an 8km one-way signal transmission. And for the first time, the echo of a submarine at 1500m was found.
After the British learned about Langevin's success, they searched for large pieces of crystal everywhere. After the crystal exhibits in the British Geological Museum were all collected, they searched again. They came to ask French crystal glasses merchants, who found a large number of crystal blocks from the warehouse to create echo detectors. After listening to the British and French delegations' introduction to Langevin's success, American scientists also stepped up research in this area.
During this time, passive sonar was also developed to determine the position of an enemy ship by listening to its noise. The earliest passive listening sonar had only two receivers and listened through a stethoscope worn on the person's head. In order to accurately determine the distance, a spatially distributed linear array with multiple hydrophones on each side was later developed. By rotating the linear array, the position of the enemy ship was determined with the ears.
Unfortunately, they did not make further achievements until the end of World War I. Ultrasonic echo detection was successful too late and failed to show its great power in the First World War.
However, the outstanding achievements of Langevin and his colleagues pioneered the application of ultrasonic testing technology.
In the years after World War I, both active and passive sonar were further developed. Britain and the United States mainly develop active sonar and use higher frequencies to make it far away from the ship's noise frequency band and not interfered by the ship's noise. For example, Langevin's sonar frequency is 38kHz, and subsequent sonar frequencies Most of them are between 10kHz and 30kHz, and because of the higher frequency, they can form strong directivity. At this time, Germany was a defeated country. According to the provisions of the Versailles Peace Treaty, it was not allowed to build submarines and could only have small-tonnage warships. Their attention was focused on developing passive listening systems. The German cruiser Prinz Eugen is equipped with a square array of 60 hydrophones on each side. It is well designed and has a great influence on the future development of passive sonar. By 1923, the echo detector jointly developed by Langevin and Shilovsky was displayed at the 50th anniversary exhibition of the French Physical Society. At that time, there were about 3,000 warships equipped with it. Different models of hydroacoustic equipment. The thermo-depth gauge appeared in 1937, which could quickly measure and calculate the changes in sound speed with depth in seawater, thereby grasping the conditions for sound propagation and laying the foundation for the further development of sonar.
Sonar, as an underwater acoustic weapon, has been fully developed during the Second World War and the post-war years. During this period, the range of sonar action continued to increase, and the ability to distinguish targets continued to improve. Various types of sonar appeared, ranging from giant sonar on nuclear submarines to guidance sonar on torpedo heads. In order to use sonar during World War II, the United States concentrated its efforts on in-depth research on the impact of sound speed distribution on sound propagation. The United States and the Soviet Union independently discovered that it was caused by hydrological distribution. "Ocean Sound Channel", where sound waves do not collide with the sea surface and the bottom of the sea, but can propagate long distances. During World War II, the warring parties lost more than a thousand submarines, most of which were discovered by sonar. After World War II, the two hegemons, the United States and the Soviet Union, engaged in an arms race, and hydroacoustic weapons were one of the important elements. With the rapid development of information theory and digital processing technology, the emergence of nuclear submarines and nuclear missiles made it possible to monitor the tactical sound of submarines at close range. Detection has developed into strategic acoustic detection for long-distance monitoring of nuclear submarines in the ocean. In order to increase the detection distance, the frequency of use of sonar is reduced to reduce the absorption of the ocean; and in order to maintain strong directionality, the number of hydrophones is increased. It needs to be added and installed according to a certain spatial distribution to form a sonar array; in order to reduce the interference of its own propeller noise, sonar is often installed at the bottom of the bow of the ship, but in this way the direction of the ship's stern becomes a blind spot that the sonar cannot search. , for this reason, it has been developed to use a tow cable to drag the sonar in the seawater at the stern of the ship, and its depth can be adjusted, which is called a variable depth sonar. This can make the sonar not affected by harsh conditions on the sea surface; in addition, the transducer The length of the array needs to be increased, but the length of the ship is limited, so a long cable is dragged behind the ship and hundreds of transducers are installed to form a towing line array several hundred meters long, which is placed on a kilometer In deep water layers, it can detect long distances; in order to quickly and widely search for submarines in a certain sea area, the method of using helicopters to drop sonobuoys has also been developed, as shown in Figure 3-8. Anti-submarine aircraft can carry 80. Multiple sonobuoys are deployed on the sea surface and are controlled by computers. They can monitor more than thirty sonobuoys at the same time and quickly conduct large-scale searches of the sea area.
After the Soviet Union disintegrated and the confrontation between the two powers disappeared. , sonar has gradually turned to research on shallow sea detection and ocean development applications. It has developed ocean acoustic tomography that can observe ocean phenomena within a range of 200 to 300 kilometers. It uses the ocean as a human body for perspective and tomography. Recently, it has developed ocean climate acoustic measurement. Temperature, measure the speed of sound in the ocean sound channel, calculate the temperature in the ocean sound channel based on the relationship between sound speed and seawater temperature, and obtain the temperature rise data due to the greenhouse effect of carbon dioxide to solve major issues of human environmental protection.
Nowadays, sonar has developed by leaps and bounds. The range of modern sonar has increased by hundreds of times, and the directional accuracy can reach a fraction of a degree, including the replacement of electronic computers and very complex large-scale integrated circuits for modern nuclear submarine sonar stations. The diameter of the transducer is several meters, the weight is ten tons, and the electricity consumption is equivalent to that of a small city. Now, in addition to shipborne sonar, huge sonar transducers are permanently deployed in ports, important straits and major waterways. Energy array, for submarines, is a dragnet woven by sonar.
In addition, anti-detection technology is also developing rapidly.
Such as noise blocking technology that interferes with sonar work, stealth technology that reduces echo reflection, and false targets that interfere with sonar operators’ judgment, etc. These are called electronic countermeasures in modern military terminology.
What’s interesting is that sonar is not a patent of humans. Many animals have their own “sonars”. Bats use their throats to emit 10-20 ultrasonic pulses per second and use their ears to receive their echoes. With this "active sonar", they can detect very small insects and metal wire obstacles with a thickness of 0.1mm. Insects such as moths also have "passive sonar" and can clearly hear the ultrasonic sound of bats 40m away, so they are often able to escape attacks. However, some bats can use high-frequency ultrasound or low-frequency ultrasound beyond the listening range of insects, so that the hit rate of catching insects is still high. It seems that animals are engaged in "sonar warfare" just like humans! Marine mammals such as dolphins and whales have "underwater sonar", which can produce a very certain signal to find food and communicate with each other.
Dolphin sonar is very sensitive and can detect metal wires with a diameter of 0.2mm and nylon ropes with a diameter of 1mm several meters away. It can distinguish two signals with a time difference of only 200μs and can detect a few hundred meters away. Schools of fish can cover their eyes and move flexibly and quickly through a pool filled with bamboo poles without touching the bamboo poles; dolphin sonar has a strong "target recognition" ability, and can not only identify different fish, but also distinguish brass , aluminum, bakelite, plastic and other different materials, it can also distinguish between the echo of its own sound and the sound wave that people record and play back; the anti-interference ability of dolphin sonar is also amazing. If there is noise interference, It will increase the intensity of its calls to cover up the noise so that its judgment is not affected; moreover, dolphin sonar also has the ability to express emotions. It has been confirmed that dolphins are animals with "language", and their "conversation" is through its sonar system. Especially the most precious of the only four freshwater dolphins that exist in the world - the white-tailed dolphin in the middle and lower reaches of the Yangtze River in my country. Its sonar system has a clear "division of labor", including positioning, communication and alarm. , and has the special function of modulating phase through frequency modulation.
A variety of whale species use sound to detect and communicate. They use sound at a much lower frequency than dolphins and have a much longer range. Other marine mammals, such as seals and sea lions, also emit sonar signals for detection.
Animals that live their whole lives in the extremely dark depths of the ocean have to use sonar and other means to search for prey and avoid attacks. The performance of their sonar is far beyond the reach of modern human technology. . Unraveling the mysteries of these animal sonar has always been an important research topic in modern sonar technology.
Like many scientific and technological developments, social needs and scientific and technological progress have promoted the development of sonar technology.
The "Ice Sea Shipwreck" event prompted the birth of the echo sounder. On April 14, 1912, the British luxury liner "Titanic" sank after colliding with an iceberg in the North Atlantic on its maiden voyage to the United States. This largest maritime accident in history caused a great shock and prompted scientists to study Detection and positioning of icebergs. British scientist L. F. Richardson applied for two patents five days and one month after the ship sank, using sound waves to detect obstacles in the air and water, and proposed the use of directional transmitting transducers, but he did not continue to work on it. His patent. In 1913, American scientist R.A. Fessenden applied for multiple patents for underwater detection and built the first echo detector using a moving coil transducer of his own design. In April 1914, he used this equipment (the 500-1000HZ sound waves emitted) to successfully detect icebergs 2 nautical miles (3.7 kilometers) away.
Following this, in 1914, the first The outbreak of the World War greatly promoted the development of hydroacoustic positioning and directional weapons. During World War I, German submarines were active and launched "infinite submarine warfare". The Allies and other countries were very annoyed and began to develop hydroacoustic equipment to detect underwater submarines. Many famous scientists participated in this work. A young Russian electrical engineer C.
Shilovsky started developing hydroacoustic detection equipment very early under the influence of shipwrecks in the ice sea. After the beginning of World War I, he recuperated in the Swiss mountains. After feeling the importance of anti-submarine warfare, he put his research into Switch to using high-frequency sound waves for submarine detection; the idea of ??echo detection. His suggestion was adopted by the French government in February 1915, and it was handed over to the famous French physicist Professor Langevin for implementation. Langevin and Shilovsky decided to use high-frequency ultrasound. They used mica electrostatic transducers, placed mica sheets in two electrodes, and applied alternating voltage to emit sound waves, using carbon particle microphones as receiving transducers. Using such crude equipment, propagation experiments were successfully carried out between the two banks of the Seine River at the end of 1915 and early 1916. It achieved one-way propagation of two kilometers and received the reflected signal from the seabed and the reflected signal from a steel plate 200m away. News of their success reached Britain, where a team was set up to develop an echo sounder.
In order to increase the detection distance, it is necessary to increase the intensity of emission and the sensitivity of reception. They used the piezoelectric effect discovered between 1880 and 1881 to generate and receive ultrasonic waves, but the piezoelectric effect was still very weak. . Coincidentally, at that time, the high-power tube high-frequency amplifier was invented in the field of electronics, which was used to amplify the piezoelectric effect. The remaining problem is to find quartz single crystals with piezoelectric effects.
In November 1917, Langevin finally persuaded an optician to donate a quartz single crystal exhibit with a diameter of about 10 inches that he had collected for many years, cut out wafers from it, and made a quartz piezoelectric receiving transducer. , equipped with a mica electrostatic emission transducer, completed the one-way signal transmission and reception of 6km. Later, quartz was used to replace mica to complete the one-way signal propagation of 8km, and the echo of a submarine at 1500m was searched for the first time.
After the British learned about Langevin's success, they searched for large pieces of crystal everywhere. After the crystal exhibits in the British Geological Museum were exhausted, they came to ask the French crystal glasses merchants, who found them from the warehouse. A large number of crystal blocks are used to create echo detectors. After listening to the British and French delegation's introduction to Langevin's success, American scientists also stepped up research in this area.
During this time, passive sonar was also developed to determine the position of an enemy ship by listening to its noise. The earliest passive listening sonar had only two receivers and listened through a stethoscope worn on the person's head. In order to accurately determine the distance, a spatially distributed linear array with multiple hydrophones on each side was later developed. By rotating the linear array, the position of the enemy ship was determined with the ears.
Unfortunately, they did not make further achievements until the end of World War I. Ultrasonic echo detection was successful too late and failed to show its great power in the First World War. However, the outstanding achievements of Langevin and his colleagues pioneered the application technology of ultrasonic testing.
In the years after World War I, both active and passive sonar were further developed. Britain and the United States mainly develop active sonar and use higher frequencies to make it far away from the ship's noise frequency band and not interfered by the ship's noise. For example, Langevin's sonar frequency is 38kHZ, and subsequent sonar frequencies Most of them are between 10 and 30kHZ, and due to the higher frequency, they can form strong directivity. At this time, Germany was a defeated country. According to the provisions of the Versailles Peace Treaty, it was not allowed to build submarines and could only have small-tonnage warships. Their attention was focused on developing passive listening systems. The German cruiser Prinz Eugen is equipped with a square array of 60 hydrophones on each side. It is well designed and has a great influence on the future development of passive sonar. By 1923, the echo detector jointly developed by Langevin and Shilovsky was displayed at the 50th anniversary exhibition of the French Physical Society. At that time, there were about 3,000 warships equipped with it. Different models of hydroacoustic equipment. The thermo-depth gauge appeared in 1937, which could quickly measure and calculate the change of sound speed in seawater with depth, thereby grasping the conditions for sound propagation and laying the foundation for the further development of sonar.
Sonar, as an underwater acoustic weapon, has been fully developed during the Second World War and the post-war years. During this period, the range of sonar action continued to increase, and the ability to distinguish targets continued to improve. Various types of sonar appeared, ranging from giant sonar on nuclear submarines to guidance sonar on torpedo heads.
In order to use sonar during World War II, the United States concentrated its efforts on in-depth research on the impact of sound speed distribution on sound propagation. The United States and the Soviet Union independently discovered that it was caused by hydrological distribution. "Ocean Sound Channel", where sound waves do not collide with the sea surface and the bottom of the sea, but can propagate long distances. During World War II, the warring parties lost more than a thousand submarines, most of which were discovered by sonar. After World War II, the two hegemons, the United States and the Soviet Union, engaged in an arms race, and hydroacoustic weapons were one of the important elements. With the rapid development of information theory and digital processing technology, the emergence of nuclear submarines and nuclear missiles made it possible to monitor the tactical sound of submarines at close range. Detection has developed into strategic acoustic detection for long-distance monitoring of nuclear submarines in the ocean. In order to increase the detection distance, the frequency of use of sonar is reduced to reduce the absorption of the ocean; and in order to maintain strong directionality, the number of hydrophones is increased. It needs to be added and installed according to a certain spatial distribution to form a sonar array; in order to reduce the interference of its own propeller noise, sonar is often installed at the bottom of the bow of the ship, but in this way the direction of the ship's stern becomes a blind spot that the sonar cannot search. , for this reason, it has been developed to use a tow cable to drag the sonar in the seawater at the stern of the ship, and its depth can be adjusted, which is called a variable depth sonar. This can make the sonar not affected by harsh conditions on the sea surface; in addition, the transducer The length of the array needs to be increased, but the length of the ship is limited, so a long cable is dragged behind the ship and hundreds of transducers are installed to form a towing line array several hundred meters long, which is placed on a kilometer In deep water layers, it can detect long distances; in order to quickly and widely search for submarines in a certain sea area, the method of using helicopters to drop sonobuoys has also been developed, as shown in Figure 3-8. Anti-submarine aircraft can carry 80. Multiple sonobuoys are deployed on the sea surface and are controlled by computers. They can monitor more than thirty sonobuoys at the same time and quickly conduct large-scale searches of the sea area.
After the Soviet Union disintegrated and the confrontation between the two powers disappeared. , sonar has gradually turned to research on shallow sea detection and ocean development applications. It has developed ocean acoustic tomography that can observe ocean phenomena within a range of 200 to 300 kilometers. It uses the ocean as a human body for perspective and tomography. Recently, it has developed ocean climate acoustic measurement. Temperature, measure the speed of sound in the ocean sound channel, calculate the temperature in the ocean sound channel based on the relationship between sound speed and seawater temperature, and obtain the temperature rise data due to the greenhouse effect of carbon dioxide to solve major issues of human environmental protection.
Nowadays, sonar has developed by leaps and bounds. The range of modern sonar has increased by hundreds of times, and the directional accuracy can reach a fraction of a degree, including the replacement of electronic computers and very complex large-scale integrated circuits for modern nuclear submarine sonar stations. The diameter of the transducer is several meters, the weight is ten tons, and the power consumption is equivalent to that of a small city. Now, in addition to shipborne sonar, huge sonar transducers are permanently deployed in ports, important straits and major waterways. For submarines, this is a dragnet woven by sonar.
In addition, anti-detection technology has also developed rapidly, such as noise blocking technology that interferes with sonar operation and reduces echo reflection. Stealth technology, as well as false targets that interfere with the sonar operator's judgment, are called electronic countermeasures in modern military terms.
What's interesting is that sonar is not a patent of humans, and many animals have their own ". "Sonar". Bats use their larynx to emit 10-20 ultrasonic pulses per second and use their ears to receive their echoes. With this "active sonar", they can detect very small insects and 0.1mm thick wire obstacles. . Insects such as moths also have "passive sonar" and can clearly hear the ultrasonic sound of bats 40m away, so they are often able to escape attacks. However, some bats can use high-frequency ultrasound or low-frequency ultrasound beyond the listening range of insects, so that the hit rate of catching insects is still high. It seems that animals are engaged in "sonar warfare" just like humans! Marine mammals such as dolphins and whales have "underwater sonar", which can produce a very certain signal to find food and communicate with each other.
Dolphin sonar is very sensitive. It can detect metal wires with a diameter of 0.2mm and nylon ropes with a diameter of 1mm several meters away. It can distinguish two signals with a time difference of only 200 seconds, and can detect hundreds of Fish schools meters away can cover their eyes and move flexibly and quickly through a pool filled with bamboo poles without touching the bamboo poles; dolphin sonar has a strong "target recognition" ability and can not only identify different fish, but also distinguish them. Brass, aluminum, bakelite, plastic and other different materials can also distinguish between the echo of its own sound and the sound wave that people record and play back; the anti-interference ability of dolphin sonar is also amazing, if there is noise Interference, it will increase the intensity of its calls to cover up the noise so that its own judgment is not affected; moreover, dolphin sonar also has the ability to express emotions. It has been confirmed that dolphins are animals with "language", and their "conversation" It is through its sonar system. Especially the most precious of the only four freshwater dolphins that exist in the world - the white-tailed dolphin in the middle and lower reaches of the Yangtze River in my country. Its sonar system has a clear "division of labor", including positioning, communication and alarm. , and has the special function of modulating phase through frequency modulation.
A variety of whale species use sound to detect and communicate. They use sound at a much lower frequency than dolphins and have a much longer range. Other marine mammals, such as seals and sea lions, also emit sonar signals for detection.
Animals that live their entire lives in the extremely dark depths of the ocean have to use sonar and other means to search for prey and avoid attacks. The performance of their sonar is far beyond the reach of modern human technology. . Unraveling the mysteries of these animal sonar has always been an important research topic in modern sonar technology
I don’t know what a paper is, so I can only help you with this. If you organize it well, you can probably put it together. Thesis is ready