Your SlideShare is downloading. ×
SONAR
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
1,016
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
138
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Shudhanshu Agarwal B.tech (EC-2011) Roll no.-1101421102
  • 2.  SONAR is originally an acronym for Sound Navigation and Ranging.  It is a technique that uses sound propagation to navigate and detect the objects located under the surface of water  The term SONAR is also used for device that generates and receives sound.  The acoustic frequencies vary from very low(infrasonic) to extremely high(ultrasonic) frequencies.
  • 3. For millions of years , its use by humans was initially recorded by Leonardo da Vinci in 1490. In 19th century, it was used as an ancillary to provide warning of hazards. Sonar was first patented by Lewis Richardson and German physicist Alexander Behm in 1913.
  • 4. During world war I the need to detect submarines prompted more research into this technology. During1930,american engineers developed their underwater sound detection technology and they began to call it SONAR coined as equivalent to RADAR
  • 5.  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
  • 6. Sonar systems are of two types: Active Sonar Passive sonar
  • 7.  It operates in three modes:  Monocratic mode  Biostatic mode  Multistate mode  Most sonars are used in monostatic mode with same array often being used for transmission and reception.
  • 8. Active sonar creates a pulse of sound often called as ping and then listens for echo of the pulse. This sound is generated by sonar projector consisting of signal generator , power amplifier, electro-acoustic array. To measure the distance of object the time from transmission of pulse to reception of pulse is measured and converted into range by knowing the sped of sound
  • 9.  The functional components are described below:  (a) Transmitter: The transmitter generates the outgoing pulse. It determines pulse width, modulation and carrier frequency.  (b)Transducer array: The individual transducers are simple elements with little or no directionality. They are arranged in an array to improve the directivity index.  The array is configured to reduce the beamwidth in vertical direction.
  • 10.  Vertical beamwidth of transducer array. (c) Beamforming processors: The input/output of each transducer is put through a beamforming processor, which applies time delays or phase shifts .
  • 11.  Active beamforming  (e) Duplexer. The duplexer performs the same function in an active sonar as in an radar system, namely to protect the receiver from full transmitter power while the pulse is going out.
  • 12.  Synchronizer: perform same function as the synchronizers in radar. Provides overall coordination and timing for system reset the display for each new pulse.  Receiver. Collects the received energy the receiver compares the power level of noise with a threshold SNR (DT) .If the DT is set too low there will be many false alarms. If it is too high, some detection capability will be lost.
  • 13.  (h) Display: Puts all the detection information into a visual format.  PPI(plan position indicator):The sonar system must sequentially search individual beams which are displayed in their true or relative form.
  • 14.  The ppi display
  • 15. Passive sonar listens without transmitting It has a wide variety of techniques to identify the source of sound. It can help in findinf nationality as most european submarines use 50hz power systems and U.S. vessels operates at 60hz a.c power systems. Passive sonar less used due to noise generated by them
  • 16. Hydrophone array :these are the sensitive elements which detect the acoustic energy emitted from target. Beamforming processor: the passive system must listen to all angles at all times. This requires very wide beamwidth.at the same time, a narrow beamwidth is required .These two objectives are achieved simultaneously by the passive beamforming processor.
  • 17.  Beamforming processors  Broadband display: The output of the beamforming processor is displayed as a bearing time history(BTH).The beamwidth of the system determines how accurately the bearing can be measured by such a
  • 18.  A typical BTH display  Frequency analyzer: the frequency analyzer breaks the signal into separate frequencies. The frequencies are divided into small bands known as frequency bins. Whose width the analysis bandwidth.
  • 19.  Frequency analysis graph
  • 20.  Sound propagation:  Sonar operation is affected by variations in sound speed .The speed is determined by:  Speed = 4388 + (11.25 × temperature (in °F)) + (0.0182 × depth (in feet)) + salinity (in parts-per- thousand).  Scattering:  When active sonar is used, scattering occurs from small objects in the sea as well as from the bottom and surface. This can be a major source of interference.
  • 21. The main uses of Sonar is as ahead: 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 to detect the locations of enemy submarines.
  • 22. 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

×