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Underwater wireless communication

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Underwater Wireless Communication is the wireless communication in which acoustic signals (waves) carry digital information through an underwater channel.

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By- Abhirami P S BCA Assumption College
INTRODUCTION  Wireless communication technology today has become part of our daily life.  It is difficult due to factors such as multi-path propagation, time variations of the channel, small available bandwidth and strong signal attenuation especially over long distance.  Underwater communications uses acoustic waves instead of electromagnetic waves.
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.
COMMUNICATION CHANNEL The signals that are used to carry digital information through an underwater channel are acoustic signals An underwater acoustic channel presents a communication system designer with many difficulties The signal is subject to multipath propagation, which is particularly pronounced on horizontal channels
DEFICIENCY IN CURRENT COMMUNICATION Radio waves propagated under water at extremely low frequencies (30Hz-300Hz) & require large antennae and high transmission power. Optical waves do not suffer much attenuation but are affected by scattering. Acoustic waves are the single best solution for communicating underwater.
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. The propagation speed of acoustic signals in water is typically 1500 m/s. It cannot rely on the Global Positioning System (GPS). Underwater wireless communication technology
UNDERWATER NETWORKS o Integrated networks of instruments, sensors, robots and vehicles will operate together in a variety of underwater environments o Depending on the application there two types of Acoustic network
 Centralized network, nodes communicate through a base station that covers one cell  In a decentralized network, nodes communicate via peer-to-peer  To accommodate multiple users within a selected network topology, the communication channel must be shared  Methods for channel sharing are based on scheduling or on contention Centralized network topology Decentralized network topology
MODEM  The modem has successfully been deployed in a number of trials  This modem is implemented in a fixed-point DSP with a floating- point co-processor  Multi-user communications each at 1.4 kbps in 5 kHz band
 Autonomous underwater vehicle (AUV) is a robot that travels underwater  Modem’s fit easily into the AUV  Low power consumption  Very reliable for high level throughput Autonomous underwater vehicle (AUV)
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.
ADVANTAGES Can be used to provide early warnings of tsunamis generated by undersea earthquakes. It avoids privacy leakage. Pollution monitoring.
DISADVANTAGES Battery power is limited and usually batteries can not be recharged easily. The available bandwidth is severely limited. High bit error rate. Multipath problems.
APPLICATIONS oMarine archaeology oSearch missions oDefence
CONCLUSION o The aim of this is to build a acoustic communication as in figure o This topic gives the overall view of the necessity of underwater wireless communication and its applications.
REFERENCE www.google.com www.Wikipedia.com
Underwater wireless communication

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Underwater wireless communication

  • 2. INTRODUCTION  Wireless communication technology today has become part of our daily life.  It is difficult due to factors such as multi-path propagation, time variations of the channel, small available bandwidth and strong signal attenuation especially over long distance.  Underwater communications uses acoustic waves instead of electromagnetic waves.
  • 3. 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.
  • 4. COMMUNICATION CHANNEL The signals that are used to carry digital information through an underwater channel are acoustic signals An underwater acoustic channel presents a communication system designer with many difficulties The signal is subject to multipath propagation, which is particularly pronounced on horizontal channels
  • 5. DEFICIENCY IN CURRENT COMMUNICATION Radio waves propagated under water at extremely low frequencies (30Hz-300Hz) & require large antennae and high transmission power. Optical waves do not suffer much attenuation but are affected by scattering. Acoustic waves are the single best solution for communicating underwater.
  • 6. 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. The propagation speed of acoustic signals in water is typically 1500 m/s. It cannot rely on the Global Positioning System (GPS). Underwater wireless communication technology
  • 7. UNDERWATER NETWORKS o Integrated networks of instruments, sensors, robots and vehicles will operate together in a variety of underwater environments o Depending on the application there two types of Acoustic network
  • 8.  Centralized network, nodes communicate through a base station that covers one cell  In a decentralized network, nodes communicate via peer-to-peer  To accommodate multiple users within a selected network topology, the communication channel must be shared  Methods for channel sharing are based on scheduling or on contention Centralized network topology Decentralized network topology
  • 9. MODEM  The modem has successfully been deployed in a number of trials  This modem is implemented in a fixed-point DSP with a floating- point co-processor  Multi-user communications each at 1.4 kbps in 5 kHz band
  • 10.  Autonomous underwater vehicle (AUV) is a robot that travels underwater  Modem’s fit easily into the AUV  Low power consumption  Very reliable for high level throughput Autonomous underwater vehicle (AUV)
  • 11. 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.
  • 12. ADVANTAGES Can be used to provide early warnings of tsunamis generated by undersea earthquakes. It avoids privacy leakage. Pollution monitoring.
  • 13. DISADVANTAGES Battery power is limited and usually batteries can not be recharged easily. The available bandwidth is severely limited. High bit error rate. Multipath problems.
  • 15. CONCLUSION o The aim of this is to build a acoustic communication as in figure o This topic gives the overall view of the necessity of underwater wireless communication and its applications.