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Underwater

Communication

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Contents

Introduction Importance of UW communication Traditional approach

Technology in use Vector sensor Architecture of Ocean Bottom

Monitoring

Differences with terrestrial network Challenges SONAR

Applications

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Introduction

Underwater communication is atechnique of sending and receiving

message below water Typical frequency: 1 Hz to 1 MHz

Hydroacoustics

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Why using sound ascommunication medium in UW-

ASN? Radio waves Optical waves

Acoustic transmission is better suited towater than air

Speed of sound in water ~ 1500m/sec Speed of sound in air ~ 340m/sec

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Why is Underwater

Communication Important? Naval defence (submarines) Ocean exploration

Understanding natural disasters(tsunami)

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Traditional approach for

ocean-bottom monitoringUses sensors to record dataDisadvantages:

Real time monitoring is not possible. No interaction b/w onshore control

systems and the monitoringinstruments.

failures or misconfigurations may occur Limited storage capacity

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Underwater Networks

Difficult to Communicate because of: Complex multi-path propagation Small bandwidth and strong attenuation Low data rates compared to terrestrial communication

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Technology In Use

Hydrophone: Converts acoustic waves into electricalenergy, Cannot measure multiple scalar quantities, and

has Single Input Single Output.

Hydrophone

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What is Vector Sensor?

Measures Pressure + Y & Z Components ofVelocity

Single Input Multiple Output More Efficient and Compact Size Therefore Vector Sensor is much more better

than other receivers

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UW-ASN 3D Architecture for

ocean bottom monitoring

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Challenges

Battery Power is limited

Limited available bandwidth

Channel characteristics

UW sensors are prone to failuresbecause of fouling, corrosion, etc

Mobility

The ocean can be as deep as 10 km

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SONAR

SOund Navigation And Ranging Two types of technology:

Active SONARPassive SONAR

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Active SONAR

Active sonar uses a soundtransmitter and a receiver Principle:

creates pinglistens echo

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Passive SONAR

Passive sonar listens withouttransmitting.

Noise limitations

Dipping sonar deployed from aShip

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Applications of Underwater

Communication Seismic monitoring. Pollution monitoring

Ocean currents monitoring Equipment monitoring and control Autonomous Underwater Vehicles (AUV)

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ThankYou

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AnyQueries??