Chris MonfredoChris JohnsonJon HoltonGreg DavisScott Hambleton

10/03/13 Rochester Institute of Technology 1

P14251Underwater Acoustic Communication

Underwater Acoustic Communication

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AgendaRevisit Customer and Engineering RequirementsFunctional DecompositionMorphological Charts

Morph DetailsPugh Analysis

Final Pugh AnalysisFinal System SelectionRisk AnalysisTest PlansSubsystem Design Schedule

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Underwater Acoustic Communication

Customer Requirements

Most important requirements:Customer Rqmt. #

Importance Description

CR1 9 Send signalCR2 9 Send signal at a rate in kb/sCR3 9 System must function underwaterCR4 9 Reliable communication schemeCR5 9 Communications must resist frequency contaminationCR6 9 Must have 2-way communication capabilities

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Engineering Requirements

Most important requirements:

Rqmt. # Priority Source Engr. Requirement (metric)Unit of

MeasureTolerance Value (+/-)

Nominal Value

Comments/StatusTest (how are you going to verify

satisfaction)S1 9 CR1 Signal Range m 5/5 30 Pool TestS2 9 CR2 Signal Rate kb/s 5 15 Pool TestS3 9 CR4 Probability of error in signal % 0/10 <10 Remove error detect/correctS4 9 CR4 Bit error detection % Compare with on vs offS5 9 CR4 Bit error correction % Compare with on vs offS6 9 CR3,CR9 Water resistant/sealed Y/N Y Hose test

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Functional DecompositionAcoustic

Communication System

Requires Power

Send Message

Receive Message

Functions Underwater

Power Converters

Generate Digital

Message

Convert Message to

Analog

Modulate Signal

Transmit Signal

Detect SignalDemodulate

Signal

Convert Message to

Digital

Analyze Message

Sinks Underwater

Water Resistant

Corrosion Resistant

Pressure Resistant

Input Data Unpack DataEncode DataCompress

DataEncrypt Data

Decompress Data

Decrypt Data

Heat Sinking

Pack DataError Check, Correct, and Decode Data

Output Data

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System Flow Diagram

Unpack DataDecompress Data

Decrypt DataError Check, Correct, and Decode Data

Output Data

Input Data Encode DataCompress Data Encrypt Data Pack Data Modulate Signal Transmit SignalComputer

Computer Receive SignalDemodulate

Signal

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Communication Protocols: ALOHA

• Easy to Implement• Inefficient – Theoretical throughput of 18%

(36% for slotted ALOHA)• Better suited for long distances

StartAssemble a Frame

of DataTransmit Data

Back off for random amount of

time

Collision? EndNO

YES

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Communication Protocols: CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance)

• Less Noise• Better Throughput• Can function with swarm expansions• Terminal Problems vs. Overhead

StartAssemble a

Frame of DataChannel

Idle?

Back off for random amount

of time

Transmit Request to Send (RTS)

Clear to Send (CTS) Received?

Transmit Data End

NO

NO

YES

YES

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Communication Protocols: CDMA(Code Division Multiple Access)

- Sends data in a unique frequency pattern - Receiver can intercept multiple signals and decode

based on the pattern

- Allows multiple, simultaneous senders with same set of frequencies• Widely-Used by 2G and 3G Devices• High Throughput• Difficult to Implement• Difficult to test – Requires more than two devices

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Error Detection and CorrectionDetection Methods:Parity BitsCyclic Redundancy Checks (CRCs)Error Correcting Code (EEC)

Correction Methods:Automatic Repeat Requests (ARQs)Forward Error Correction (FEC)Hybrid Schemes (Both ARQ and FEC)

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Encryption and CompressionEncryption Methods: Triple DES (56-bit) AES (128-bit) If not enough time, something simple (XOR the bit stream)

Compression Methods: Lossless Algorithms Lossy Algorithms

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Computational PowerMicroprocessors: Low Price Low Complexity Efficient Fairly Versatile Many microprocessors to choose from

Other options (regular processors, FPGAs, ASICs) are too expensive, complicated, and far beyond the scope of this project.

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Power ConvertersTransformer

High voltage step-down or positive and negative voltage

Buck Converter High efficiency step-down

Linear Regulator Easy to implement but low efficiency

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Amplitude Modulation

Easy to ImplementRequires more power than other schemesCarrier frequency must be about 10X data rate

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Frequency Modulation

Susceptible to frequency shifts due to Doppler effect or sound speed changesCarrier frequency is move flexible than AM

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Phase Shift Keying

Harder to implement than FM but more resistant to noiseMore bandwidth efficient than FM

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Quadrature Amplitude Modulation

Hardest to implementCan encode the most amount of informationSusceptible to noise

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Corrosion ResistantMaterial Selection

Metals Plastics

Corrosion Resistant Coating Barrier Galvanization

Water ResistanceGasket/O-ringsCaulk/SealantTight Fit

Pressure ResistanceStructural Strength/Case DesignInternal Pressurization

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Dissipate HeatHeat sinkFanLiquid cooling

Use external water Use internal system

Image from: http://en.wikipedia.org/wiki/File:Heatsink_povray.png

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Morphological ChartPower Converters Transformer Buck Converter Linear Converter

Data Input Computer Auto-GeneratedError Detection Parity bits CRCs EECs

Error Correction ARQs FECs Hybrid Scheme(De)Compression Lossless Algorithms Lossy Algorithms

(De)Encryption XOR the bit stream Triple DES AESComm. Protocol CSMA/CA Aloha CDMA Custom Design(De)Modulation AM FM Phase QAM

Sinks Underwater Internal Weight External WeightWater Resistant O-Rings Metal-on-Metal Sealant Glue

Corrosion Resistant Metal Selection Coatings Plastic SelectionPressure Resistant Case Design Internal Presure

Dissipate Heat Heat Sink Fan External Liquid Internal Liquid

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Pugh AnalysisRound 1

Computer Computer Auto Auto Computer Auto ComputerParity CRCs EECs EECs CRCs Parity CRC'sARQs FECs Hybrid ARQs Hybrid FECs ARQs

Lossless Lossy Lossy Lossless Lossy Lossy LosslessTriple DES AES XOR Triple DES AES XOR Triple DESCSMA/CA Aloha CDMA Custom CSMA/CA Aloha CDMA

Phase AM FM QAM Phase AM FMInternal Weight External Weight External Weight Internal Weight Internal Weight Internal Weight External Weight

Oring Glue M-on-M Oring Glue Oring GlueMaterial Plastic Coating Galvanization Galvanize Coating Material

Case Design Presurized Presurized Case Design Case Design Presurized Case DesignHeat Sink Fan Internal Liquid External Liquid Heat Sink Fan Fan

Power Use Datum - - - = - =Communication Error Rate Datum = - = + - =

Ease of implementation Datum = - + = + =User friendly Datum - = + - + -

Cost Datum + - - = - +Probability of Catastrophic Failure Datum - - = - = -

Effi ciency Datum - = = + - ++'s 1 0 2 2 2 2-'s 4 5 2 2 4 2

Round 2 DatumComputer Computer Auto Auto Computer Auto Computer

Parity CRCs EECs EECs CRCs Parity CRC'sARQs FECs Hybrid ARQs Hybrid FECs ARQs

Lossless Lossy Lossy Lossless Lossy Lossy LosslessTriple DES AES XOR Triple DES AES XOR Triple DESCSMA/CA Aloha CDMA Custom CSMA/CA Aloha CDMA

Phase AM FM QAM Phase AM FMInternal Weight External Weight External Weight Internal Weight Internal Weight Internal Weight External Weight

Oring Glue M-on-M Oring Glue Oring GlueMaterial Plastic Coating Galvanization Galvanize Coating Material

Case Design Presurized Presurized Case Design Case Design Presurized Case DesignHeat Sink Fan Internal Liquid External Liquid Heat Sink Fan Fan

Power Use = - = - Datum - =Communication Error Rate - - = = Datum - =

Ease of implementation = + - - Datum + =User friendly + = - + Datum + =

Cost = + - - Datum - +Probability of Catastrophic Failure + - - + Datum + =

Effi ciency - - - - Datum - ++'s 2 2 0 2 3 2-'s 2 4 5 4 4 0

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Finalized Pugh AnalysisGeneration of hybrid between two best systems

System 1 System 2 Hybrid SystemData Input Computer Computer Computer

Error Detection Parity CRC's CRC'sError Correction ARQs ARQs ARQs

(De)Compression Lossless Lossless Lossless(De)Encryption Triple DES Triple DES Triple DES

Comm. Protocol CSMA/CA CDMA CSMA/CA(De)Modulation Phase FM Phase

Sinks Underwater Internal Weight External Weight Internal WeightWater Resistant Oring Glue Oring

Corrosion Resistant Material Material MaterialPressure Resistant Case Design Case Design Case Design

Dissipate Heat Heat Sink Fan Heat Sink

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Final System SelectionData Input Computer

Error Detection CRC'sError Correction ARQs

(De)Compression Lossless(De)Encryption Triple DES

Comm. Protocol CSMA/CA(De)Modulation Phase

Sinks Underwater Internal WeightWater Resistant Oring

Corrosion Resistant MaterialPressure Resistant Case Design

Dissipate Heat Heat Sink

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Risk Analysis

Major Concerns: Speaker, Data Loss, and Carrier Frequency Loss

Minor Concerns: Power Surge, Short Circuiting, Watertight Case, and Bad Parts

ID Problem Likelyhood Damage Importance Mitigation Owners1 The housing isn't watertight 2 3 6 Test waterproofing and test the empty housing SH, GD2 Short circuit 1 3 3 CJ, CM3 Damage due to mis-handling parts 1 2 2 Team must be c areful with components All4 Loss of carrier frequency 2 3 6 Have a robust communication scheme in place CJ, CM5 Power loss 1 1 1 CM6 Power Surge 1 3 3 Surge Protection CM7 Data loss 2 3 6 Have tested error correction/detection JH8 Overheat microprocessor 1 3 3 Use effi cient code and have thermal management JH, GD9 Corrosion breach 1 3 3 Galvanize or use corrosion resistant materials SH, GD

10 Speaker doesn't work 3 3 9 Invest heavily in research & design to ensure working part CJ, CM11 Ordered components do not match specs 2 3 6 Order from reputable sources with return policies GD

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Test PlansASTM B117-11 Salt Spray Test

IPX7 Submersion Testing

Operating Temperature Testing

Error Correction Testing

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Subsystem Design Schedule

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Questions?