The document discusses underwater wireless communication, which uses acoustic signals to transmit digital information underwater. It provides an introduction to underwater wireless communication technology and its history. The document outlines the necessity of underwater wireless communication when wired solutions are not feasible. It also describes underwater wireless communication technologies, including acoustic modems and underwater acoustic sensor networks. The document discusses applications, advantages, and disadvantages of underwater wireless communication and concludes by discussing opportunities for further development in the field.

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Seminar
On
Underwater Wireless
Communication

2. Content
 Introduction
 History
 Necessity of Underwater Wireless Communication
 Underwater Wireless Communication Technology
 Applications
 Advantages
 Disadvantages
 Conclusion
 Reference

3. Introduction
• Underwater wireless communication is the wireless
communication in which acoustic signals (waves) carry
digital information through an underwater channel.
• Technique of sending and receiving message under the
utilization of sound propagation in underwater
environment is known as acoustic communication.
• Among the types of waves, acoustic waves are used
as the primary carrier for underwater
wirelesscommunication systems due to the relatively low
absorption in underwater environments.

4. History
 The science of underwater acoustics began in 1490,
• when Leonardo Da Vinci, stated.
 In 1687 Isaac Newton wrote his Mathematical
Principles of Natural Philosophy which included the
first mathematical treatment of sound in water.

5. Necessity of Underwater Wireless
Communication
Wired underwater is not possible in all situations as
shown below-:
• Temporary experiments
• Breaking of wires
• Significant cost of deployment
• Experiment over long distances.
To cope up with above situations, we require
underwater wireless communication.

6. Underwater Wireless Communication
Technology
• Radio waves do not propagate well underwater due
to the high energy absorption of water.
• Therefore, underwater communication are based on
acoustic links characterized by large propagation
delays.
• Acoustic channels have low bandwidth.

7. Cont…
• The signal that are used to carry digital information
through an underwater channel are acoustic channel.
• The propagation speed of acoustic signals in water is
typically 1500 m/s.
• It cannot rely on the Global Positioning System (GPS).

8. Factors Influencing Acoustic
Communication
• Path loss: Due to attenuation and geometric
spreading.
• Noise: Man-made noise and ambient noise(due to
hydrodynamics)
• Multi-path propogation
• High propogation delay
• Doppler frequency spread.

9. Hardware Platform Interfaces
• Sensor Interface:
– Must develop common interface with different sensors (chemical,
optical, etc.) and communication elements (transducer) .
– Wide (constantly changing) variety of sensors, sampling strategies
• Communication Interface:
Amplifiers, Transducers
Signal modulation
Hardware:
 Software Defined Acoustic Modem (SDAM)
 Reconfigurable hardware known to provide, flexible, high
performance implementations for DSP applications

10. Acoustic Modem
• Employ advanced modulation scheme and channel
equalization for improved signal to noise ratio.
• Employ high performance error detection and correction
coding scheme which reduces bit error rate to less than 10-
7
Parts of an acoustic modem:
• DSP Board
• AFE(Analog Front End) Board
• DC/DC Converter

11. Data Transmission in Modem
When no data is being transmitted, the modem stays in
sleep mode, it periodically wakes up to receive possible
data being transmitted by far end modem. This results in
low power consumption. Similarly when the data is to be
transmitted , the modem receives data from its link in
sleep mode and then switches to transmit mode and
transmit the data.

12. Advanced Modems Available

13. Underwater Acoustic Sensor Networks
(UW-ASN)
• Group of sensors and vehicles deployed
underwater and networked via acoustic links,
performing collaborative tasks.
• Equipment
– Autonomous Underwater Vehicles (AUVs)
– Underwater sensors (UW-ASN)

14. UW-ASN Communication Architecture
2-D ARCHITECTURE

15. 3-D Architecture

16. Applications
• Seismic monitoring.
• Pollution monitoring
• Ocean currents monitoring
• Equipment monitoring and control
• Autonomous Underwater Vehicles (AUV)
• Remotely operated vehicle(ROV)
• Acoustic navigation technology for multiple AUVs.
• Solar Powered AUVs

17. Advantages
• Can be used to provide early warnings of
tsunamis generated by undersea earthquakes.
• It avoids data spoofing.
• It avoids privacy leakage.
• Pollution monitoring.

18. Disadvantages
• Battery power is limited and usually batteries cannot
be recharged also because solar energy cannot be
exploited .
•
• The available bandwidth is severely limited.
• Channel characteristics including long and variable
propagation delays.
• Multipath and fading problems.
• High bit error rate.

19. Conclusion
Despite much development in this area of the
underwater wireless communication, there is still an
immense scope so more research as major part of the
ocean bottom yet remains unexploded.
The main objective is to overcome the present limitations
and implement advanced technology for oceanographic
research and cope up with the environmental effects on
the noise performance of acoustic systems to compete
with the future challenges like effective transmission of
audio and video signals etc.

20. Reference
• www.google.com
• www.wikipedia.com
• www.studymafia.org

21. THANK YOU

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