Presented By:-

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SWAPNIL HOLE(17) AKSHAY BRAMHANE(18) AMEY DANDGE(19) KSHITIJ S. DASTURE (20)GUIDED BY:-

Prof.P.A.PATHADE

HISTORYy In the 19th century an underwater bell was used as an

ancillary to lighthouses to provide warning of hazards.y The world's first patent for an underwater echo

ranging device was developed at the British Patent Office by English meteorologist Lewis Richardson ,and a German physicist Alexander Behm obtained a patent for an echo sounder in 1913.

GENERAL CONCEPT ABOUT SONARySONAR

is an abbrevation for

SOUND NAVIGATION And RANGING. It is a technique that uses sound propagation (usually underwater, as in Submarine navigation) to navigate, communicate with or detect other vessels.

GENERAL CONCEPT ABOUT SONARy Sonar may be used as a means of acoustic location and

of measurement of the echo characteristics of "targets" in the water.y The acoustic frequencies used in sonar systems vary

from very low (infrasonic) to extremely high (ultrasonic).

BLOCK DIAGRAM OF SONARBlock diagram using waves. Simple block diagram.

SONAR equipment mounted at the base of ship.

WORKING OF THE SYSTEMy When a target is detected, the bearing is

determined by the listening equipment. y The echo-ranging transducer is trained to the target bearing and a single short ping is emitted. y The echo-ranging equipment on a submarine is used most often for navigation and only as required for target ranging.

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SWAPNIL

DIGITAL CONTROL ROOM

DIGITAL CIRCUIT

TRANSMITTER CIRCUIT

The Transmitter circuit emitts sound waves in the water.The transmitter consists of a ultrasonic transducer which emits ultrasonic waves in water.this transducer is controlled by a digital circuit consisting of IC s & other electronic components.

RECEIVER CIRCUIT

The receiver circuit receives sound waves in the water which are reflected from the obstacle.The receiver consists of a ultrasonic transducer ,this transducer is driven by a digital circuit consisting of IC LM567 which acts as a Tone decoder .

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AKASHY

MAINLY TWO TYPESyActive Sonaremitting pulses of sounds and listening for echoes.

yPassive Sonaris essential only listening for the sound made by vessels.

ACTIVE SONARy Active sonar uses a sound transmitter and a receiver. y When the two are in the same place it is monostatic

operation. y When the transmitter and receiver are separated it is bistatic operation. y When more transmitters (or more receivers) are used, again spatially separated, it is multistatic operation. y Most sonars are used monostatically with the same array often being used for transmission and reception.

ACTIVE SONARy Active sonar creates a pulse of sound, often

called a "ping", and then listens for reflections (echo) of the pulse. y This pulse of sound is generally created electronically using a sonar Projector consisting of a signal generator, power amplifier and electro-acoustic transducer/array.

PASSIVE SONARy Passive sonar listens without transmitting. y It is often employed in military settings, although it is also used in science applications, e.g., detecting fish for presence/absence studies in various aquatic environment.

PASSIVE SONARy Passive sonar detects the target's radiated

noise characteristics. y The radiated spectrum comprises a continuous spectrum of noise with peaks at certain frequencies which can be used for classification.

SOUND PROPAGATIONSonar operation is affected by variations in sound speed, particularly in the vertical plane. Sound travels more slowly in fresh water than in sea water, though the difference is small. The speed is determined by the water's bulk modulus and mass density.

ECHO SOUNDINGy The value of underwater acoustics to the fishing industry has led to the development of other acoustic instruments that operate in a similar fashion to echo-sounders but, because their function is slightly different from the initial model of the echo-sounder.

Sonar Systemsy Generally, the electro-acoustic transducers are of the

Tonpilz type and their design may be optimised to achieve maximum efficiency over the widest bandwidth, in order to optimise performance of the overall system.

y To measure the distance to an object, the time from

transmission of a pulse to reception is measured and converted into a range by knowing the speed of sound. To measure the bearing, several hydrophones are used, and the set measures the relative arrival time to each, or with an array of hydrophones, by measuring the relative amplitude in beams formed through a process called beamforming. Use of an array reduces the spatial response so that to provide wide cover multibeam systems are used.

y Identifying sound sources y Passive sonar has a wide variety of techniques for

identifying the source of a detected sound. For example, U.S. vessels usually operate 60 Hz alternating current power systems. If transformers or generators are mounted without proper vibration insulation from the hull or become flooded, the 60 Hz sound from the windings can be emitted from the submarine or ship.

APPLICATIONSy Warfarey 1. Anti-submarine warfare- A conventional hull mounted sonar is used y 2. Torpedoes-Modern torpedoes are generally fitted with an active/passive

sonar. This may be used to home directly on the target. required target

y 3. Mines-Mines may be fitted with a sonar to detect, localize and recognize the y 4. Submarine navigation-Submarines rely on sonar to a greater extent than

surface ships as they cannot use radar at depth. divers.

y 5. Underwater security-Sonar can be used to detect frogmen and other scuba

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Civilian applicationsunderwater applications since sound travels farther and faster underwater than in air. transducer mounted on the headline of the net rather than on the bottom of the vessel. measuring a ship's velocity either relative to the water or to the bottom.

y 1. Fisheries- Acoustic technology is especially well suited for

y 2. Net location-The net sounder is an echo sounder with a

y 3. Ship velocity measurement-Sonars have been developed for

y Scientific applicationsy 1. Biomass estimation y 2. Wave measurement y 3. Water velocity measurement y 4. Bottom type assessment y 5. Bottom topography measurement y 6. Sub-bottom profiling y 7. Synthetic aperture sonar y 8. Parametric sonar

Refrences

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y Fahy, Frank (1998). Fundamentals of noise and

vibration. John Gerard Walker. Taylor & Francis. y Hill, M. N. (1962). Physical Oceanography. Allan R. Robinson. Harvard University Press. y H O Berktay, Some Finite Amplitude Effects in Underwater Acoustics in V M Albers "Underwater Acoustics" 1967

Refrences & extern. linksWashingtony External links y Sonar Tutorial for Robots

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y Fisheries Acoustics Research (FAR) at the University of

y Sonars and the marine environment by Norwegian

Defence Research Establishment (FFI) y Single Beam Sonars

THANK-YOU

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