ECE 4901 Final PresentationTeam 2117: Underwater Data TransferRyan Harvey, Kiran Nadkarni, Harris Yousafzai

Project Overview - Sponsored by General Dynamics Electric

Boat (Contact: Eric Hultgren)

- Designing a Wireless Data Transfer System

for Underwater Use

- Theoretical Use Case Between UUV and

Submarine

- Collaboration Between ECE, CSE, and MechE

2

Specifications and Constraints

- Minimum Accepted Data Transfer Rate: 100

kBps

- Maximum Goal Data Transfer Rate: 1 GBps

- Transfer Quality: 100% No Lost Packets

- Maximum Data Transfer Equipment Current: 3 A

- Maximum Exposed Terminal voltage: 30 VDC

- Materials and components selected must be:

- Corrosion Resistant

- Seawater Capable

- Depth capable for UUV

- Safe for Underwater Life

- Maximum Distance of 30 Ft.

- Operating Temperature of (0°C - 36.6°C)

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Specifications Cont. - Riptide UUV Specifications

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Source: Electric Boat

Source: Electric Boat

Figure 1: Picture of Riptide UUV

Table 1: Specifications of Riptide UUV

Background - Revisited

- Optical Communication: Alternative to

Acoustic & RF

- Advantages:

- Much higher Data Rate (~Gbps)

- Low Latency

- Low attenuation (~0.39 dB/m

Ocean)

- Much more energy efficient

(~30,000 bits/J)

- Higher Speed (~2.225x10^8 m/s)

5

Background - Revisited

- Optical Communication: Alternative to

Acoustic & RF

- Disadvantages:

- Not available as COTS product

- No clear industry standard optical

platform

- Potential for LOS issues

- High degree of complexity

6

Approach/Design - Optical/Laser based Data Transfer System

- Deliverables

- MATLAB/Simulink model

- Modulation Scheme source code

- Thermal analysis and theoretical waterproof

casing

- Scaled down PoC hardware implementation

- Roles of ECE alongside MechE and CSE for this

project

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Approach/Design - Optical Communication System

- Blue light

- 10mW - 5W optical transmission power

- Operating Temperature of -5°C - 40°C

- LED/Semiconductor Laser (~405 - 450 nm

wavelength)

- Photodiode Receiver

- Microprocessor/Arduino Modulation

- Appropriate Amplifier Circuit for Transmitter

- Factors of Data Rate and Information Loss

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Figure 2: Block diagram of system

Expected Deliverables

- Continually developed Research Presentation

- Existing research into various optical

platforms

- Costs/Benefits of various optical

technologies

- Potential for integration into UUV units

- Potential for scaling to multi-unit

communication

- Proof of Concept Hardware Implementation

- Scaled-down hardware and output data rate

9

Simulink Model Structure

● Three Part General System:

○ Signal Generation

○ Undersea Channel Dynamics

○ Signal Reception

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Simulink Model Structure

● Undersea Channel Dynamics

Modeled as General Second Order

State Space approximation

● Specific Dynamics based on

Propagation loss as a function of

wavelength and distance traveled

● System specified to determine

Transmitted, Absorbed and

Scattered Power 11

Simulink Model Structure

Undersea Channel Dynamics are generally

split into two categories:

○ LOS (Line of Sight) Links

○ NLOS (non-Line of Sight) Links

Active research uses one of two methods to

model Undersea Channels:

○ Gauss-Seidel Numerical

Approximation (Ultimately

Producing a SS Approximation)

○ Monte-Carlo Simulation of

Dynamics 12

Simulink Model Structure

Signal Generation will consist of three

components:

○ Original Signal Information

○ Pulse Width Modulation

○ Laser Diode Dynamics

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Simulink Model Structure

Signal Reception will also consist of

three components:

○ Photodiode Dynamics

○ Pulse Width Demodulation

(within the Arduino)

○ Filtering and Reconstruction

(What the Arduino Sends

Outward)

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Tentative Part List

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Table 2: Index of Potential Circuit Parts

Circuit Diagrams(Transmitter)

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D1450nm

Laser Diode

GND

Figure 3: Diagram of Transmitter Circuit

Circuit Diagram(Receiver)

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D1450 nm

Photodiode

GND

D2 LED

Figure 4: Diagram of Receiver Circuit

Modulation Technologies

- Direct Modulation & External Modulation

- Coherent Mod. & Intensity Mod.

- Commonly Used Protocols:- On-Off Keying- Pulse Position Modulation- Pulse Width Modulation- Phase Shift Keying- Quadrature Amplitude Modulation

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FEC Channel Coding - Necessary to combat Attenuation of Seawater

- Practice of including redundancy into message

- Benefits are seen to Range and Power Use- Slight Detriment to Maximum Bandwidth - Commonly Used Coders

- Block Codes- Low Density Parity Check- Reed Solomon- Turbo/Trellis Coded Modulation- Convolutional

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Project Management

20Table 3: Gantt Chart of Project Timeline

Project Management

21Table 4: RACI Chart of Team Responsibilities

References - Underwater Optical Wireless Communication

Oliveira & Salas 2020 REPSOL

- General Dynamics EB Capstone Project

Details

- Sponsor Provided Notional Parameters and

Requirements

- Riptide UUV specifications Documentation

- Journal of Optoelectronics and Advanced

Materials

- On the Use of a Direct Radiative Transfer

Equation Solver for Path Loss Calculation in

Underwater Optical Wireless Channels IEEE

Wireless Communications 201522