SONAR TECHNOLOG

Y RICHA TRIPATHI

CONTENTS Introduction History of sonar Types of Sonar Application Limitation New innovation of sonar How it works Conclusion Video

introduction Sonar,which in itself originally an acronym for sound

navigation & ranging.

Sonar is a device that is used to detect underwater objects using sound waves.

In this system a sound pulse is generated and sent underwater through a transmitter.

Sound waves are reflected by the underwater object which are received at receiver.

The time taken by sound wave to come back is recorded.

And by knowing the speed of sound wave in water the distance can be easily calculated by formula.

Distance = speed x time

The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic).

history We know that some animals (dolphins and bats) have use

sound as a medium of communication and objects detection for millions of years.

But use of the sound by humans in the water is initially recorded by Leonardo da Vinci in 1490: a tube inserted into the water was said to be used to detect vessels by placing an ear to the tube.

Sonar was first patented by Lewis Richardson and German physicist Alexander Behm in 1913.

The first measurement of sound speed in 1826

Type of sonar ACTIVE SONAR

PASSIVE SONAR

Active sonar Active sonar uses sound

transmitter and receiver . And there are 3 modes of operation :

Monostatic mode

Bistatic mode

Multistatic mode

Monostatic mode : When the transmitter and receiver are at the same place.

Bistatic mode : When the transmitter and receiver are separated by some distance.

Multistatic mode : When more transmitters (or more receivers) are used, again spatially separated.

Passive sonar Passive sonar listens without

transmitting. Passive sonar has a wide variety

of techniques for identifying the source of a detected sound.

Passive sonar system have large sonic database but sonar operator classify signals by use of computer and use these databases to identify classes of ships and action.

Application It is used to find the actual depth of the sea.

Sonar systems are used to find lost ships and submarines.

These are used in ocean surveillance systems.

They are used by navy detect the locations of enemy submarines.

They are used for under water security.

Limitation It has an adverse effects on marine animals

like dolphins and whales ,that also use sound waves for their navigation.

It leads whales to painful and often fatal decompression sickness.

The sonar systems generate lot of noise.

High intensity sonar sounds can create a small temporary shift in the hearing threshold of some fish.

SONAR NEW INNOVATION ON MARCH 16,2016

NEW INnovation OF SONAR

FORGET TINY MOBILES KEYBOARD YOU COULD SOON TYPE IN MID-AIR & SURFACE.

A new sonar technology developed by a lead author Rajlakshmi Nandkumar a student in University of Washington,and some computer scientists and electrical engineers that allows you to interact with mobile devices by writing or gesturing on any nearby surface -- a tabletop, a sheet of paper or even in mid-air.

Finger io A new sonar technology called Finger IO will make it easier to

interact with screens on smartwatches and smartphones by simply writing or gesturing on any nearby surface. It’s is an active sonar system using the device’s own microphones and speakers to track fine-grained finger movements (to within 8mm).

Two microphones are needed to track finger motion in two dimensions, and three for three dimensions. So this system may work (when available commercially) with some smartphones (it was tested with a Samsung Galaxy S4).

It also track subtle finger motion around the device,even when the phone is inside a pocket.

HOW IT WORKS

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The device’s own speaker to release an inaudible sound wave which we can’t heard.These are called Orthogonal Frequency Division Multiplexing.

That signal rebounds off the finger, and those “echoes” are recorded by the device’s microphones and helped to estimate the finger’s current place in space.

WORKING The minimum difference between the

drawings and the FingerIO tracings was 0.8 centimetres for the smartphone and 1.2 centimetres for the smartwatch.

The scientists developed a FingerIO prototype app for smartphone and a smartwatch equipped with two microphones, which are required to track finger motion in two dimensions

conclusion It’s very easy way of typing and after

sometime we use this technique.

Finger IO makes it easier than ever to interact with devices that have small screens.

Finger IO does not require any special finger instrumentation, sensors or hardware. 

Sonar tech

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