Related message:

"ECHO, ECHO SOUNDER,

ECHOLOCATION"

The work of students in the 9th grade

Kosogorova Andrey

School No. 8 MO RF

Sevastopol

ECHO(on behalf of the nymph Echo in ancient Greek mythology), a wave (acoustic, electromagnetic, etc.) reflected from an obstacle and accepted by an observer. Acoustic echo can be observed, for example, when a sound impulse (knock, short staccato cry, etc.) is reflected from highly reflective surfaces. The echo is audible if the received and sent pulses are separated by a time interval t 5= 50-60 ms. The echo becomes multiple if there are several reflective surfaces (near a group of buildings, in the mountains, etc.), the sound from which comes to the observer at times that differ by t intervals of 50-60 ms. harmonic echo. occurs when sound with a wide spectrum of frequencies is scattered by obstacles whose dimensions are small compared to the wavelengths that make up the spectrum. In a room, individual numerous echoes merge into a continuous echo, called reverberation. The echo can serve as a means of measuring the distance from the signal source to the reflecting object: r = st/2, where t is the time interval between the sending of the signal and the return of the echo, and c is the speed of wave propagation in the medium. Various echo applications are based on this principle. Acoustic echo is used in sonar, as well as in navigation, where echo sounders are used to measure the depth of the bottom. Electromagnetic echo is used in radar; reflecting from the ionosphere, it makes it possible to carry out short-wave radio communication over long distances and to judge the properties of the ionosphere. The echo-wave principle is beginning to be applied in the optical range of electromagnetic waves generated by a quantum optical generator. Elastic waves propagating in the earth's crust, reflecting from layers of various rocks, form a seismic echo. This is used to search for mineral deposits. With the help of Echo, the depth of boreholes is measured (“echometry” of wells), the height of the liquid level in tanks (ultrasonic level gauges). Echo methods are widely used in ultrasonic flaw detection. acoustic echo. for some animals (bats, dolphins, whales, etc.) it serves as a means of orientation and search for prey (see Sound location).

ECHOLOCATION(from echo and lat. locatio - placement) in animals, the radiation and perception of reflected, usually high-frequency, sound signals in order to detect objects in space, as well as obtain information about the properties and sizes of targets being located (prey or obstacles). Echo is one of the ways animals orient themselves in space. Echo is developed in bats and dolphins, found in shrews, a number of species of pinnipeds (seals), birds (salangans and some others). In dolphins and bats, echo is based on the emission of ultrasonic pulses with a frequency of up to 130-200 kHz, with a signal duration usually from 0.2 to 4-5 ms, sometimes more. With the help of an echo, dolphins, even with their eyes closed, can find food not only during the day, but also at night, determine the depth of the bottom, the proximity of the coast, and submerged objects. A person perceives their echolocation impulses as the creak of a door turning on on rusty hinges. Whether echolocation is characteristic of baleen whales, which emit signals with a frequency of only a few kilohertz, has not yet been clarified.

Dolphins send sound waves in a direction. The fat pad lying on the jaw and premaxillary bones and the concave anterior surface of the skull act as a sound lens and reflector: they concentrate the signals emitted by the air sacs and direct them in the form of a sound beam to the object being located.

In birds living in dark caves (guajaro and salangans), it is used for orientation in the dark; they emit low-frequency signals of 7-4 kHz. In dolphins and bats, in addition to the general orientation, the echo serves to determine the spaces, position of the target, size, and in some cases, to recognize the appearance of the target. In the mammals mentioned above, it often serves as an important means of finding and obtaining food items.

Lit .: Airapetyants E. Sh., Konstantinov A. I., Echolocation in nature, 2nd ed., L., 1974. G. N. Simkin. ECHOLOCATION, one of the methods of sound location, in which the distance to an object is determined by the time of return of the echo signal.

Echo sounder(from echo and lot), a navigation device for automatically measuring the depth of water bodies using hydroacoustic echo signals. Usually, a vibrator is installed in the bottom of the vessel, to which electrical impulses are periodically supplied from the generator, which are converted by it into acoustic ones, propagating vertically downward in a limited solid angle. The acoustic impulse reflected by the bottom is received by the same vibrator, which converts it into an electric one. After amplification, the pulse enters the depth indicator, which marks the time interval (in sec) from the moment the pulse was sent to the moment the echo returns from the bottom and converts it into visual indications or a depth record h = st/2 in m, where the speed of sound is c = 1500 m/ sec. The pulse duration is from 0.05 to 20 ms with a filling frequency from 10 to 200 kHz. Short durations and high frequencies are used when measuring shallow depths, long durations and low frequencies are used when measuring great depths. The vibrator can be a magnetostrictive or piezoceramic transducer. As depth indicators, flashing indicators with a rotating neon light flashing at the moment of receiving an echo signal are used; pointer, electron-beam and digital indicators, as well as recorders that record measured depths on a moving paper tape using an electrothermal or electrochemical method. Echo sounders are manufactured for different depth intervals, ranging from 0.1 to 12,000 m, and operate at vessel speeds of up to 30 knots (55 km/h) and even more. Sonar error from 1% to hundredths of a percent. The echo sounder is also used to search for schools of fish, submarines, to study sound scattering layers, determine the type of soil, stratify bottom sediments and other hydroacoustic measurements. In 1958, the maximum depth (11,022 m) of the World Ocean in the Mariinsky depression in the western part of the Pacific Ocean was detected and accurately measured by an echo sounder on the Soviet ship Vityaz. Several people came up with the idea of ​​an echo sounder independently and almost simultaneously: German engineer A. Bem from Danzig (Gdansk), American engineer R. A. Fessenden, French physicist P. Langevin and engineer Konstantin Vasilievich Shilovsky (1880-1952) from Ryazan who worked in France. Langevin and Shilovsky also created the first sonar

See Hydroacoustics.

Lit .: Fedorov I. I., Navigation echo sounders, M.-L., 1948; his, Echo sounders and other hydroacoustic means, L., 1960; Tolmachev D., Fedorov I., Navigation echo sounders, "Technique and weapons", 1977, No. 1. I.I. Fedorov.

ECHOENCEPHALOGRAPHY(from echo and encephalography), ultrasound encephalography, a method of studying the brain using ultrasound. It is based on the property of ultrasound to be reflected from the boundaries of media (structural formations of the brain) of different density. The main diagnostic criterion (proposed in 1955-56 by the Swede, doctor L. Leksell) is the deviation of the median echo, or M-echo (M - from late Latin te-dialis - median), which is a reflection of ultrasound from the median structures of the brain (pineal gland, 3 ventricle, septum pellucidum, interhemispheric fissure). Normally, the M-echo, recorded as a peak on the ultrasound encephalogram, coincides with the midline of the head. In the presence of an intracranial tumor, hemorrhage, abscess, and other pathological formations, the M-echo is shifted towards the healthy hemisphere (see Fig.). Other diagnostic criteria have also been proposed: an increase in the distance between echo signals from the lateral walls of the 3rd ventricle in hydrocephalus; relatively fast normalization of the resulting displacement of the M-echo in acute obstruction of the carotid artery, etc. In ECHOENCEPHALOGRAPHY, special ultrasonic encephalographs are used that convert the reflected ultrasonic signals into electrical impulses. These pulses are displayed graphically on the screen of the device and photographed.

Lit .: Clinical echoencephalography, M., 1973; L e ks e 1 1 L., Echo-encephalog" raphy. Detection of intracranial complications following head injury, "Acta chirurgica scan" dinavica", 1956, v. 110, S. 301-315.

V. E. Grechko.

ECHO, a compositional and performing technique based on the repetition of muses. phrases with less sonority by the same or other voices, instruments.

It is used mainly in choral, opera, orchestral, chamber instrumental music. Based on the use of the echo technique, entire musical plays are sometimes created, for example, O. Lasso's "Echo" for the choir and a play of the same name. from the "French Overture" for harpsichord by J. S. Bach. Echo name is also one of the registers of the organ.

Lit .: R e l e and J., Theory of sound, trans. from English, 2nd ed., vol. 2, M., 1955; Gr and f f and n D., Echo in the life of people and animals, trans. from English, M., 1961.

• Read: Communication and language of animals
• Read more: Rumor. auditory analyzer

Essence of echolocation

The word "location" means determining the location of objects, measuring their coordinates and motion parameters. In wildlife, various forms and methods of location are used. In humans and most animals, the determination of the location of surrounding objects is carried out thanks to remote-action analyzer systems, mainly visual and auditory, and these systems are functionally brought to the highest perfection in some animals. Suffice it to recall the extraordinary visual acuity of diurnal birds of prey or the accuracy of sound direction finding of prey by owls.

Some animals also use other types of information to detect environmental objects. Deep-sea squids, for example, in addition to the usual organs of vision, are endowed with special receptors capable of capturing infrared rays, and the peculiar organs - “thermolocators” - of rattlesnakes serve to search for prey, perceiving the thermal radiation of living beings and reacting to a temperature difference of a thousandth of a degree.

The examples given, despite their diversity, are different variants of the so-called passive location, when objects are detected only by receiving the energy that is directly emitted or re-emitted by the objects themselves.

Relatively recently, it seemed that the more or less sensitive organs of remote detection as means of passive location limited the possibilities of wildlife.

At the very beginning of the 20th century. humanity had the right to be proud of the fact that it created a fundamentally new, active method of location, in which a previously invisible target is irradiated with a stream of electromagnetic or ultrasonic energy and detected using the same energy, but already reflected from the target. Radio and sonar stations - these active location devices - have replaced various kinds of "hearers" - passive detection devices - and have now received tremendous development in solving economic, military and space problems. At the same time, there is no doubt that the principles of radar prompted biologists the way to solving the problem of the forms of spatial orientation in some animals, which could not be explained by the functioning of well-known remote action analyzers.

As a result of painstaking research with the help of new electronic equipment, it was possible to establish that a number of animals use active location methods using two types of energy - acoustic and electrical. Electric location is used by some tropical fish, such as sea-mirus, or water elephant, while active acoustic location is discovered in several representatives of terrestrial and aquatic vertebrates at different levels of evolutionary development.

Acoustic location serves as a means of detecting objects due to sound waves propagating in a given environment.

By analogy with radar, two forms of acoustic location are distinguished: passive, when detection is carried out only by receiving the energy that is directly emitted or re-emitted by the objects under study themselves, and to-t and in nu yu, in which the analysis of the object is based on preliminary irradiation of it sound signals with subsequent perception of the same energy, but already reflected from it. The first form of acoustic location has long been referred to as hearing or auditory perception, and sound vibrations are received by the auditory analyzer.

The second form, i.e., active acoustic location, was called echolocation by the American scientist D. Griffin, who first discovered it in bats. Over time, the terms "echolocation", "acoustic location" and "acoustic orientation" have become to some extent synonymous and are widely used in the biological literature to describe the active form of location in animals. True, in recent years, attempts have been made to use the terms "acoustic location", "passive location" to refer to the functions of the auditory system in owls, which with high accuracy localize the location of their prey by ear during night hunting (Ilyichev, 1970; Payne, 1971) . By this they want to emphasize the enormous role that hearing plays in the feeding behavior of owls, and to compare the ways of orientation of these birds with those of bats, although this comparison is not valid, because the latter have risen to the next, qualitatively new level of acoustic location, using active space probing own acoustic signals. Before turning to the characteristics of echolocation, let us briefly dwell on the basic concepts and definitions from the field of acoustics necessary for understanding the physical stimuli of the auditory receptor apparatus.

E.Sh.AIRAPETYANTS A.I.KONSTANTINOV. ECHOLOCATION IN NATURE. Publishing house "NAUKA", LENINGRAD, 1974

Related message:

"ECHO, ECHO SOUNDER,

ECHOLOCATION"

The work of students in the 9th grade

Kosogorova Andrey

School No. 8 MO RF

Sevastopol

ECHO(on behalf of the nymph Echo in ancient Greek mythology), a wave (acoustic, electromagnetic, etc.) reflected from an obstacle and accepted by an observer. Acoustic echo can be observed, for example, when a sound impulse (knock, short staccato cry, etc.) is reflected from highly reflective surfaces. The echo is audible if the received and sent pulses are separated by a time interval t 5= 50-60 ms. The echo becomes multiple if there are several reflective surfaces (near a group of buildings, in the mountains, etc.), the sound from which comes to the observer at times that differ by t intervals of 50-60 ms. harmonic echo. occurs when sound with a wide spectrum of frequencies is scattered by obstacles whose dimensions are small compared to the wavelengths that make up the spectrum. In a room, individual numerous echoes merge into a continuous echo, called reverberation. The echo can serve as a means of measuring the distance from the signal source to the reflecting object: r = st/2, where t is the time interval between the sending of the signal and the return of the echo, and c is the speed of wave propagation in the medium. Various echo applications are based on this principle. Acoustic echo is used in sonar, as well as in navigation, where echo sounders are used to measure the depth of the bottom. Electromagnetic echo is used in radar; reflecting from the ionosphere, it makes it possible to carry out short-wave radio communication over long distances and to judge the properties of the ionosphere. The echo-wave principle is beginning to be applied in the optical range of electromagnetic waves generated by a quantum optical generator. Elastic waves propagating in the earth's crust, reflecting from layers of various rocks, form a seismic echo. This is used to search for mineral deposits. With the help of Echo, the depth of boreholes is measured (“echometry” of wells), the height of the liquid level in tanks (ultrasonic level gauges). Echo methods are widely used in ultrasonic flaw detection. acoustic echo. for some animals (bats, dolphins, whales, etc.) it serves as a means of orientation and search for prey (see Sound location).

ECHOLOCATION(from echo and lat. locatio - placement) in animals, the radiation and perception of reflected, usually high-frequency, sound signals in order to detect objects in space, as well as obtain information about the properties and sizes of targets being located (prey or obstacles). Echo is one of the ways animals orient themselves in space. Echo is developed in bats and dolphins, found in shrews, a number of species of pinnipeds (seals), birds (salangans and some others). In dolphins and bats, echo is based on the emission of ultrasonic pulses with a frequency of up to 130-200 kHz, with a signal duration usually from 0.2 to 4-5 ms, sometimes more. With the help of an echo, dolphins, even with their eyes closed, can find food not only during the day, but also at night, determine the depth of the bottom, the proximity of the coast, and submerged objects. A person perceives their echolocation impulses as the creak of a door turning on on rusty hinges. Whether echolocation is characteristic of baleen whales, which emit signals with a frequency of only a few kilohertz, has not yet been clarified.

Dolphins send sound waves in a direction. The fat pad lying on the jaw and premaxillary bones and the concave anterior surface of the skull act as a sound lens and reflector: they concentrate the signals emitted by the air sacs and direct them in the form of a sound beam to the object being located.

In birds living in dark caves (guajaro and salangans), it is used for orientation in the dark; they emit low-frequency signals of 7-4 kHz. In dolphins and bats, in addition to the general orientation, the echo serves to determine the spaces, position of the target, size, and in some cases, to recognize the appearance of the target. In the mammals mentioned above, it often serves as an important means of finding and obtaining food items.

Lit .: Airapetyants E. Sh., Konstantinov A. I., Echolocation in nature, 2nd ed., L., 1974. G. N. Simkin. ECHOLOCATION, one of the methods of sound location, in which the distance to an object is determined by the time of return of the echo signal.

Echo sounder(from echo and lot), a navigation device for automatically measuring the depth of water bodies using hydroacoustic echo signals. Usually, a vibrator is installed in the bottom of the vessel, to which electrical impulses are periodically supplied from the generator, which are converted by it into acoustic ones, propagating vertically downward in a limited solid angle. The acoustic impulse reflected by the bottom is received by the same vibrator, which converts it into an electric one. After amplification, the pulse enters the depth indicator, which marks the time interval (in sec) from the moment the pulse was sent to the moment the echo returns from the bottom and converts it into visual indications or a depth record h = st/2 in m, where the speed of sound is c = 1500 m/ sec. The pulse duration is from 0.05 to 20 ms with a filling frequency from 10 to 200 kHz. Short durations and high frequencies are used when measuring shallow depths, long durations and low frequencies are used when measuring great depths. The vibrator can be a magnetostrictive or piezoceramic transducer. As depth indicators, flashing indicators with a rotating neon light flashing at the moment of receiving an echo signal are used; pointer, electron-beam and digital indicators, as well as recorders that record measured depths on a moving paper tape using an electrothermal or electrochemical method. Echo sounders are manufactured for different depth intervals, ranging from 0.1 to 12,000 m, and operate at vessel speeds of up to 30 knots (55 km/h) and even more. Sonar error from 1% to hundredths of a percent. The echo sounder is also used to search for schools of fish, submarines, to study sound scattering layers, determine the type of soil, stratify bottom sediments and other hydroacoustic measurements. In 1958, the maximum depth (11,022 m) of the World Ocean in the Mariinsky depression in the western part of the Pacific Ocean was detected and accurately measured by an echo sounder on the Soviet ship Vityaz. Several people came up with the idea of ​​an echo sounder independently and almost simultaneously: German engineer A. Bem from Danzig (Gdansk), American engineer R. A. Fessenden, French physicist P. Langevin and engineer Konstantin Vasilievich Shilovsky (1880-1952) from Ryazan who worked in France. Langevin and Shilovsky also created the first sonar

See Hydroacoustics.

Lit .: Fedorov I. I., Navigation echo sounders, M.-L., 1948; his, Echo sounders and other hydroacoustic means, L., 1960; Tolmachev D., Fedorov I., Navigation echo sounders, "Technique and weapons", 1977, No. 1. I.I. Fedorov.

ECHOENCEPHALOGRAPHY(from echo and encephalography), ultrasound encephalography, a method of studying the brain using ultrasound. It is based on the property of ultrasound to be reflected from the boundaries of media (structural formations of the brain) of different density. The main diagnostic criterion (proposed in 1955-56 by the Swede, doctor L. Leksell) is the deviation of the median echo, or M-echo (M - from late Latin te-dialis - median), which is a reflection of ultrasound from the median structures of the brain (pineal gland, 3 ventricle, septum pellucidum, interhemispheric fissure). Normally, the M-echo, recorded as a peak on the ultrasound encephalogram, coincides with the midline of the head. In the presence of an intracranial tumor, hemorrhage, abscess, and other pathological formations, the M-echo is shifted towards the healthy hemisphere (see Fig.). Other diagnostic criteria have also been proposed: an increase in the distance between echo signals from the lateral walls of the 3rd ventricle in hydrocephalus; relatively fast normalization of the resulting displacement of the M-echo in acute obstruction of the carotid artery, etc. In ECHOENCEPHALOGRAPHY, special ultrasonic encephalographs are used that convert the reflected ultrasonic signals into electrical impulses. These pulses are displayed graphically on the screen of the device and photographed.

Lit .: Clinical echoencephalography, M., 1973; L e ks e 1 1 L., Echo-encephalog" raphy. Detection of intracranial complications following head injury, "Acta chirurgica scan" dinavica", 1956, v. 110, S. 301-315.

V. E. Grechko.

ECHO, a compositional and performing technique based on the repetition of muses. phrases with less sonority by the same or other voices, instruments.

It is used mainly in choral, opera, orchestral, chamber instrumental music. Based on the use of the echo technique, entire musical plays are sometimes created, for example, O. Lasso's "Echo" for the choir and a play of the same name. from the "French Overture" for harpsichord by J. S. Bach. Echo name is also one of the registers of the organ.

Lit .: R e l e and J., Theory of sound, trans. from English, 2nd ed., vol. 2, M., 1955; Gr and f f and n D., Echo in the life of people and animals, trans. from English, M., 1961.

And dolphins emit ultrasound. Why is this needed and how does it work? Let's look at what echolocation is and how it helps animals and even people.

What is echolocation

Echolocation, also called biosonar, is a biological sonar used by several animal species. Echolocating animals radiate signals into the environment and listen to the echoes of those calls that are returned from various objects near them. They use these echoes to find and identify objects. Echolocation is used for navigation and for fodder (or hunting) in various conditions.

Principle of operation

Echolocation is the same as active sonar, which uses sounds produced by the animal itself. Ranging is done by measuring the time delay between the animal's own sound emission and any echoes returning from the environment.

Unlike some human-made sonar, which rely on extremely narrow beams and multiple receivers to locate a target, animal echolocation is based on one transmitter and two receivers (ears). The echoes returning to the two ears arrive at different times and at different volume levels, depending on the position of the object generating them. Differences in time and volume are used by animals to perceive distance and direction. With echolocation, a bat or other animal can see not only the distance to an object, but also its size, what kind of animal it is, and other features.

The bats

Bats use echolocation for navigation and foraging, often in total darkness. They usually emerge from their roosts in caves, attics, or trees at dusk and hunt for insects. Thanks to echolocation, bats are in a very advantageous position: they hunt at night when there are many insects, there is less competition for food, and there are fewer species that can prey on the bats themselves.

Bats generate ultrasound through their larynx and emit sound through their open mouth or, much less commonly, their nose. They emit sound ranging from 14,000 to over 100,000 Hz, mostly outside the human ear (typical human hearing range is 20 Hz to 20,000 Hz). Bats can estimate the movement of targets by interpreting patterns caused by reflections of echoes from a special flap of skin in the outer ear.

Individual species of bats use echolocation in specific frequency bands that are appropriate for their living conditions and prey types. This has sometimes been used by researchers to identify the species of bats that inhabit the area. They simply recorded their signals with ultrasonic recorders known as bat detectors. In recent years, researchers in several countries have developed bat call libraries that contain records of native species.

Sea creatures

Biosonar is valuable to the suborder of toothed whales, which includes dolphins, killer whales and sperm whales. They live in an underwater habitat that has favorable acoustic characteristics and where vision is extremely limited due to the turbidity of the water.

The most significant early results in describing dolphin echolocation were achieved by William Shevill and his wife Barbara Lawrence-Shevill. They were engaged in feeding dolphins and once noticed that they unmistakably find pieces of fish that silently fell into the water. This discovery was followed by a number of other experiments. So far, dolphins have been found to use frequencies ranging from 150 to 150,000 Hz.

The echolocation of blue whales has been much less studied. So far, only assumptions have been made that the “songs” of whales are a way of navigating and communicating with relatives. This knowledge is used to count the population and to track the migrations of these marine animals.

rodents

It is clear what echolocation is in marine animals and bats, and why they need it. But why do rodents need it? The only terrestrial mammals capable of echolocation are two genera of shrews, teireks from Madagascar, rats, and slit-tooths. They emit a series of ultrasonic squeaks. They do not contain reverberant echolocation responses and appear to be used for simple spatial orientation at close range. Unlike bats, shrews only use echolocation to study prey habitats and not to hunt. With the exception of large and thus highly reflective objects (such as a large rock or tree trunk), they are probably not capable of unraveling echo scenes.

The most talented sonar

In addition to these animals, there are others that can engage in echolocation. These are some species of birds and seals, but the most sophisticated echo sounders are fish and lampreys. Previously, scientists considered bats to be the most capable, but in recent decades it has become clear that this is not the case. The air environment is not conducive to echolocation - unlike water, in which sound diverges five times faster. The sonar of fish is the organ of the lateral line, which perceives the vibrations of the environment. Used for both navigation and hunting. Some species also have electroreceptors that pick up electrical vibrations. What is fish echolocation? It is often synonymous with survival. She explains how blinded fish could live to a respectable age - they did not need sight.

Echolocation in animals has helped explain similar abilities in visually impaired and blind people. They navigate in space with the help of clicking sounds they make. Scientists say that such short sounds emit waves that can be compared to the light of a flashlight. At the moment, there is too little data to develop this direction, since capable sonar among people is a rarity.

Orientation system in space

Direction:

Executor: 10th grade student Dmitry Tyukalov

Supervisor: Evgeniy Aminov

Physics teacher

Introduction. 3

Chapter I. Echolocation. 4

I.1. Story. 4

I.2. Principles of echolocation. 4

I.3. Application methods. 5

I.5. Measurement principle. 12

I.6. Types of devices. thirteen

Chapter II. Arduino. 14

II.1. Application. 14

II.2. Programming language. 14

II.3. Differences from other platforms. 14

Conclusion. eighteen

List of literature and Internet sources. eighteen

Appendix. nineteen

Introduction

Nowadays, people are gradually developing devices that make our life easier. And of course, without orientation, they would be inferior. In this paper, we will consider in detail one of the types of orientation - echolocation. The object of my research is orientation by the method of echolocation, which we consider using the example of an autonomous device created on the basis of Arduino. The problem is whether it is convenient and effective.

The aim of this work was: identifying the pros and cons of orientation based on the principle of echo location.

To achieve this goal, it is necessary to solve the following tasks:

1. Study the essence of the phenomenon.

2. Explore a standalone Arduino device.

3. Create a device.

4. Writing a program.

5. Testing in various conditions.

6. Find a worthy application.

This issue has not been developed in the past, but the very phenomenon of echo location was considered by Pierre Curie in 1880, and its application in life became possible thanks to Alexander Bem in 1912. He created the world's first echo sounder.

I guess that orientation by the principle of echolocation is very effective and will be able to help people in life-threatening situations.

Chapter I. Echolocation

I would like to start from afar, namely with the definition:

Echolocation (echo and lat. locatio - “position”) is a method by which the position of an object is determined by the delay time of the return of the reflected wave. If the waves are sound, then this is sonar, if the radio is radar.

I.1. Story

Echolocation as a phenomenon in robotics and mechanics came from biology. Its discovery is associated with the name of the Italian naturalist Lazzaro Spallanzani. He drew attention to the fact that bats fly freely in a completely dark room without touching objects. In his experiment, he blinded several animals, but even after that they flew on a par with sighted ones. Spallanzani's colleague J. Zhyurin conducted another experiment in which he covered the ears of bats with wax, and the animals stumbled upon all objects. From this, scientists concluded that bats navigate by ear. However, this idea was ridiculed by contemporaries, since nothing more could be said - short ultrasonic signals at that time were still impossible to fix.

The idea of ​​active sound location in bats was first put forward in 1912 by H. Maxim. He hypothesized that bats create low-frequency echolocation signals by flapping their wings at a frequency of 15 Hz.

The Englishman H. Hartridge, who reproduced the experiments of Spallanzani, guessed about ultrasound in 1920. Confirmation of this was found in 1938 thanks to bioacoustics D. Griffin and physicist G. Pierce. Griffin coined the name echolocation to refer to the way bats navigate using ultrasound.

I.2. Principles of echolocation

Echolocation begins with ultrasound, so let's learn more about it.

Like many other physical phenomena, ultrasonic waves owe their discovery to chance. In 1876, the English physicist Frank Galton, studying the generation of sound by whistles of a special design (Helmholtz resonators), now bearing his name, discovered that at certain chamber sizes, sound ceases to be audible. It could be assumed that the sound simply does not radiate, but Galton concluded that the sound is not heard because its frequency becomes too high. In addition to physical considerations, the reaction of animals (primarily dogs) to the use of such a whistle testified in favor of this conclusion.

Obviously, it is possible to emit ultrasound using whistles, but not very convenient. The situation changed after the discovery of the piezoelectric effect by Pierre Curie in 1880, when it became possible to emit sound without blowing an air stream through the resonator, but by applying an alternating electrical voltage to the piezoelectric crystal. However, despite the emergence of fairly convenient sources and receivers of ultrasound (the same piezoelectric effect allows you to convert the energy of acoustic waves into electrical vibrations) and the huge successes of physical acoustics as a science associated with such names as William Strutt (Lord Rayleigh), ultrasound was considered mainly as an object for study, but not for application.

I.3. Application methods

The next step was taken in 1912, when just two months after the sinking of the Titanic, an Austrian engineer Alexander Bem created the world's first echo sounder. Imagine how history could change! From that time until now, ultrasonic sonar has remained an indispensable tool for surface and submarine ships.

Another fundamental shift in the development of ultrasound technology was made in the 1920s. XX century: in the USSR, the first experiments were carried out on the sounding of solid metal by ultrasound with reception at the opposite edge of the sample, and the recording technique was designed so that it was possible to obtain two-dimensional shadow images of cracks in the metal, similar to X-rays (pipe S.A. Sokolov). Thus began ultrasonic flaw detection, which allows you to "see the invisible."

Obviously, the use of ultrasound could not be limited to technical applications. In 1925 the outstanding French physicist Paul Langevin, engaged in equipping the fleet with echo sounders, investigated the passage of ultrasound through human soft tissues and the effect of ultrasonic waves on the human body. The same S.A.Sokolov in 1938 he received the first tomograms of a human hand “in the light”. And in 1955, British engineers Ian Donald and Tom Brown built the world's first ultrasound tomograph, in which a person was immersed in a bath of water, and an operator with an ultrasound emitter and an ultrasound receiver had to go around the object of research in a circle. They were the first to apply the principle of echolocation to a person and received not a translucent, but a reflective tomogram.

The next fifty years (practically up to the present day) can be characterized as an era of penetration of ultrasound into all sorts of areas of technical and medical diagnostics and the use of ultrasound in technological areas, where it often allows you to do what is impossible in nature. But more on that.

Perhaps the most important application of echolocation in engineering is the non-destructive testing of structures (metal, concrete, plastic) to detect defects in them caused by mechanical loads. In the simplest case, a flaw detector is an echo sounder, on the screen of which an echogram is displayed. By moving the ultrasonic sensor over the surface of the inspected product, it is possible to detect cracks. Typically, a flaw detector is equipped with a set of ultrasonic transducers that allow ultrasound to be introduced into the material at different angles, and an audible alarm signaling that the reflected echo signal exceeds the threshold.

Among metal structures, the most important object of non-destructive testing is railway rails. Despite significant progress in the introduction of automation, manual control is most common on Russian railways. The multi-channel sonar is mounted on a removable trolley pushed by the operator. Ultrasonic sensors are installed in skis sliding on the rail tread surface. To ensure acoustic contact, tanks with contact liquid are installed on the trolley (water in summer, alcohol in winter). And thousands of operators walk along all railways, pushing carts, in snow and rain, in heat and frost... The requirements for the design of equipment are high - the devices must operate in the temperature range from -40 to +50 ° C, be dust and moisture resistant, work from battery. The first domestic rail flaw detectors in the USSR were created 50 years ago by prof. A.K. Gurvich in Leningrad. The development of computer technology has made it possible in the last decade to create automated flaw detectors that allow not only to detect a defect, but also to record the entire echogram of the path traveled for viewing information, storing it and further analyzing it in special centers. One of these devices - ADS-02 - was created by the staff of our IAP RAS together with the Meduza company and is mass-produced by the Nizhny Novgorod plant named after. M. Frunze. To date, more than 300 devices are operating on Russian railways, helping to detect several thousand so-called acute defects, each of which can cause a crash. In 2005 ADS-02 flaw detector won the 1st place at the international competition for embedded systems developers in San Francisco (USA) for the use of modern computer technologies.

Ultrasonic thickness gauges are used for continuous measurement of the thickness of a sheet (steel, glass) during production, as well as the thickness of an object that is accessible only from one side (for example, the wall thickness of a container or pipe). Here, one often has to deal with very small delays, therefore, to improve the accuracy of measurements, echo sounder looping is used: the first received echo signal immediately starts the transmitter to emit the next pulse, etc., while not the delay time is measured, but the start frequency.

Echo sounders, whose development began almost a hundred years ago, are now used on a wide variety of objects, from surface and underwater warships to inflatable boats of recreational fishermen. The use of computers made it possible not only to display the bottom profile on the echo sounder screen, but also to recognize the type of reflecting object (fish, driftwood, silt, etc.). With the help of echo sounders, maps of the shelf profile are compiled, daily fluctuations in the depth of the plankton layer in the ocean were discovered.

Unlike X-ray and NMR tomographs (as well as the first "through" ultrasound devices), modern devices for ultrasound examination of organs (ultrasound) operate in the same mode as their counterparts in technical diagnostics, i.e. detect interfaces between media with different acoustic characteristics. The difference between the properties of soft tissues does not exceed 10%, and only bone tissues give almost 100% reflection. Thus, almost all the wealth of information received by medical ultrasound devices lies in the analysis of these weak signals.

One of the first applications of one-dimensional location in medicine was the ultrasound echoencephaloscope. Its idea is simple: echograms of intracranial structures are obtained by probing the head in the temporal region on the left and right. The appearance of intracranial lesions (hematomas, tumors) leads to a violation of the symmetry of echograms, and such patients can be easily identified and sent for a more detailed and expensive examination.

The use of ultrasound in cardiology has led to the development of an important technology for ultrasound - the presentation of an echogram in depth-time coordinates, when the signal amplitude is represented by the gray level. This made it possible to start systematic non-invasive studies of the movement of the internal structures of the heart and large vessels and to obtain new important physiological information. For example, it has been proven that the cross section of the aorta does not change, as doctors previously assumed.

The first cardiac devices were one-dimensional, and to examine different structures, it was necessary to rotate the probe at different angles. Subsequently, it was possible to automate this process, and modern ultrasound devices became echotomographs, i.e. allow to obtain two-dimensional sections of the studied area of ​​the body and observe the rapid movement of the structural elements of the heart - valves, partitions. In the case of fixed structures, everything is much simpler. The first ultrasound tomograms were obtained when there were no sophisticated electronics and computers, however, for this it was necessary to immerse a person in a bath of water and go around with a one-dimensional sensor in a circle. Now methods of interference of oscillations from many small elements are used, which allow controlling the direction of the ultrasonic beam. Such an ultrasound examination (ultrasound) of organs and tissues has become a common procedure, incomparably cheaper than other types of tomography.

At the same time, private applications of one-dimensional ultrasonic location remained. One of them is the measurement of the thickness of the subcutaneous fat, which allows you to evaluate the degree of obesity, for example, BFI. This method is implemented in the Bodymetrix2000 device, a joint Russian-American development, which is now used in beauty salons and fitness clubs around the world.

Perhaps the most interesting of the complex modern devices for ultrasound medical diagnostics are three-dimensional systems. In these systems, the ultrasound beam is rotated in two mutually perpendicular directions, and the received echo signals are processed in such a way as to obtain an image of the continuous surface of an object inside the human body, whether it is an internal organ or an embryo. If the collection and processing of information is fast enough, then it is possible to observe the movement of an object in real time, for example, to study the behavior of an unborn child, his reactions, etc. Perhaps the only issue here is to ensure safety, i.e. maintaining the intensity of ultrasonic radiation at the level of 50–100 mW/cm2.