underwater optical communication - feup

© Bernardo Silva – [email protected]

Underwater Optical Communication:

An Approach Based on LED

Bernardo Miguel Carvalho Silva

o Supervisor: Nuno Alexandre Cruz

o Co-Supervisors: José Carlos Alves, Dr. Luís Manuel Pessoa (INESC TEC)


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• Objectives

• Context

• System Design

• Implementation

• Test and Results

• Conclusions

• Future Work

Outline



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Assembly of a LED and photo-sensor based test system

• Creation of a underwater wireless link that enables the transmission of information

• Create a system that enables the test of different transmission parameters

Create a real-life solution

• Create a solution that could be used in a robotic platform

Test the system in different environments

• Laboratory Tests

• Laboratory Pool Tests

• Apply different external condition in the performance

ObjectivesObjectives Context System Design Implementation

Tests and Results

Conclusions Future Work


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Difficulties:

• Radio communication is highly attenuated underwater

• Sonar transmissions are typically used in this application

• Underwater wireless transmission is a challenging task

Advantages:

• Certain gaps in the electromagnetic spectrum have low attenuation

• It can reach high data-rates with small latency

• Possible solution for short range communications

ContextObjectives Context System Design Implementation

Tests and Results



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System DesignObjectives Context System Design Implementation

Tests and Results


Preliminary system design


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System DesignObjectives Context System Design Implementation

Tests and Results


Final system design


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Design Constrains:

• Small size;

• Low weight; and

• Low complexity.

System Design

Design Requirements:

• Maximum range;

• High data-rate; and

• Low power.

Objectives Context System Design ImplementationTests and Results



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Optical Transmitter – Tx

Optical Receiver – Rx

Physical Casing

Proposed Prototype

ImplementationObjectives Context System Design Implementation

Tests and Results



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• Light Source and Light Source Driver:

‒ Focusing Lens

‒ 7 LEDs MCPCB

‒ MOSFET

‒ MOSFET Driver


Tests and Results



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• Light Source and Light Source Driver:

‒ Focusing Lens

‒ 7 LEDs MCPCB

‒ MOSFET

‒ MOSFET Driver


Tests and Results



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• Photo-Receiver

‒ Blue/Green Enhanced Photodiodes

• Current-to-voltage converter

‒ Transimpedance Amplifier

• Buffer


Tests and Results



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• Amplification and filtration

‒ Band pass filter

• Digital output

‒ Comparator


Tests and Results



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Physical Casing


Tests and Results



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Proposed Prototype

• Configurable solution

‒ Layer design

• Usable in a autonomous underwater robotic platform


Tests and Results



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Proposed Prototype


Tests and Results



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Test Platform

• Align the pair transmitter/receiver

• Estimate the range of the transmission

• Change the orientation of the modules


Tests and Results



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Laboratory “Control” Tests

• Check if the basic internal concept works

Laboratory Workbench Tests

• Check if the module with the casing works

Laboratory Pool Tests

• Prove that the concept fulfils the basic objectives

Tests and ResultsObjectives Context System Design Implementation

Tests and Results



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Tests and Results



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• Maximum range

• Influence of the external lights

• Performance of the focusing

lens

Preliminary Conclusions

• The power consumption in

order of the range behaves like

an exponential;

• The blue transmission

outperforms the green

transmission; and

• The focusing lens enhances

the range of the link.


Tests and Results



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Tests and Results



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• Maximum range


• Influence of the deviation

• Behaviour of each casing type

Conclusions

• The power consumption in order

of the range behaves like an

exponential;



transmission; and

• The deviation of 15 degrees high

enhances the transmission.


Tests and Results



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Tests and Results



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• Maximum range


• Influence of the deviation

Conclusions

• The power consumption in order

of the range behaves like an

exponential;



transmission; and

• The deviation of 15 degrees high

enhances the transmission.


Tests and Results



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The main objectives were

accomplished

A experimental system was

created, implemented and

tested in real life conditions

Vast possibilities for future

work

ConclusionsObjectives Context System Design Implementation

Tests and Results



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Possible upgrades to the hardware can be implemented

The layer based system enables the test of different modules for

transmitting and receiving information

The test platform can also suffer an upgrade

New case studies can be proposed based on this system

Future WorkObjectives Context System Design Implementation

Tests and Results



Thanks for your attention!

Obrigado pela vossa atenção!

underwater optical communication - feup

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