P14251
Underwater Acoustic Communication
Chris Monfredo
Chris Johnson
Jon Holton
Greg Davis
Scott Hambleton
10/03/13
Rochester Institute of Technology
1
Underwater Acoustic Communication
Agenda
Revisit Customer and Engineering Requirements
Functional Decomposition
Morphological Charts
 Morph Details
Pugh Analysis
Final Pugh Analysis
Final System Selection
Risk Analysis
Test Plans
Subsystem Design Schedule
10/03/13
Rochester Institute of Technology
2
Underwater Acoustic Communication
Customer Requirements

Most important requirements:
Customer
Importance
Description
Rqmt. #
CR1
9
Send signal
CR2
9
Send signal at a rate in kb/s
CR3
9
System must function underwater
CR4
9
Reliable communication scheme
CR5
9
Communications must resist frequency contamination
CR6
9
Must have 2-way communication capabilities
10/03/13
Rochester Institute of Technology
3
Underwater Acoustic Communication
Engineering Requirements

Most important requirements:
Rqmt. # Priority
S1
S2
S3
S4
S5
S6
9
9
9
9
9
9
10/03/13
Source
CR1
CR2
CR4
CR4
CR4
CR3,CR9
Engr. Requirement (metric)
Signal Range
Signal Rate
Probability of error in signal
Bit error detection
Bit error correction
Water resistant/sealed
Unit of Tolerance
Measure Value (+/-)
m
5/5
kb/s
5
%
0/10
%
%
Y/N
Nominal
Value
30
15
<10
Rochester Institute of Technology
Comments/Status
Y
4
Test (how are you going to verify
satisfaction)
Pool Test
Pool Test
Remove error detect/correct
Compare with on vs off
Compare with on vs off
Hose test
Underwater Acoustic Communication
Functional Decomposition
Acoustic
Communication
System
Requires
Power
Send
Message
Heat Sinking
Receive
Message
Functions
Underwater
Sinks
Underwater
Power
Converters
Generate
Digital
Message
Convert
Message to
Analog
Modulate
Signal
Transmit
Signal
Detect Signal
Demodulate
Signal
Convert
Message to
Digital
Analyze
Message
Water
Resistant
Corrosion
Resistant
Pressure
Resistant
Input Data
10/03/13
Compress
Data
Encrypt Data
Encode Data
Pack Data
Unpack Data
Error Check,
Correct, and
Decode Data
Rochester Institute of Technology
Decrypt Data
5
Decompress
Data
Output Data
Underwater Acoustic Communication
System Flow Diagram
Computer
Input Data
Compress Data
Encrypt Data
Encode Data
Pack Data
Modulate Signal
Transmit Signal
Computer
Output Data
Decompress
Data
Decrypt Data
Error Check,
Correct, and
Decode Data
Unpack Data
Demodulate
Signal
Receive Signal
10/03/13
Rochester Institute of Technology
6
Underwater Acoustic Communication
Communication Protocols: ALOHA
Start
Assemble a Frame
of Data
NO
Transmit Data
Collision?
End
Back off for
random amount of
time
•
•
•
Easy to Implement
Inefficient – Theoretical throughput of 18%
(36% for slotted ALOHA)
Better suited for long distances
10/03/13
Rochester Institute of Technology
7
YES
Underwater Acoustic Communication
Communication Protocols: CSMA/CA
(Carrier Sense Multiple Access/Collision Avoidance)
Back off for
random amount
of time
NO
NO
Start
Assemble a
Frame of Data
Transmit
Request to
Send (RTS)
Channel
Idle?
Clear to
Send (CTS)
Received?
YES
YES
•
•
•
•
Less Noise
Better Throughput
Can function with swarm expansions
Terminal Problems vs. Overhead
10/03/13
Rochester Institute of Technology
Transmit Data
8
End
Underwater Acoustic Communication
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
10/03/13
Rochester Institute of Technology
9
Underwater Acoustic Communication
Error Detection and Correction
Detection Methods:
Parity Bits
Cyclic Redundancy Checks (CRCs)
Error Correcting Code (EEC)
Correction Methods:
Automatic Repeat Requests (ARQs)
Forward Error Correction (FEC)
Hybrid Schemes (Both ARQ and FEC)
10/03/13
Rochester Institute of Technology
10
Underwater Acoustic Communication
Encryption and Compression
Encryption Methods:
 Triple DES (56-bit)
 AES (128-bit)
 If not enough time, something simple (XOR the bit stream)
Compression Methods:
 Lossless Algorithms
 Lossy Algorithms
10/03/13
Rochester Institute of Technology
11
Underwater Acoustic Communication
Computational Power
Microprocessors:
 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.
10/03/13
Rochester Institute of Technology
12
Underwater Acoustic Communication
Power Converters
Transformer
 High voltage step-down or positive and
negative voltage
Buck Converter
 High efficiency step-down
Linear Regulator
 Easy to implement but low efficiency
10/03/13
Rochester Institute of Technology
13
Underwater Acoustic Communication
Amplitude Modulation
Easy to Implement
Requires more power than other schemes
Carrier frequency must be about 10X data rate

10/03/13
Rochester Institute of Technology
14
Underwater Acoustic Communication
Frequency Modulation
Susceptible to frequency shifts due to Doppler effect or
sound speed changes
Carrier frequency is move flexible than AM

10/03/13
Rochester Institute of Technology
15
Underwater Acoustic Communication
Phase Shift Keying
Harder to implement than FM but more resistant to noise
More bandwidth efficient than FM

10/03/13
Rochester Institute of Technology
16
Underwater Acoustic Communication
Quadrature Amplitude Modulation
Hardest to implement
Can encode the most amount of information
Susceptible to noise

10/03/13
Rochester Institute of Technology
17
Underwater Acoustic Communication
Water Resistance
Gasket/O-rings
Caulk/Sealant
Tight Fit

Structural Strength/Case Design
Internal Pressurization
10/03/13
Material Selection

Metals

Plastics
Corrosion Resistant Coating

Barrier

Galvanization

Pressure Resistance

Corrosion Resistant
Rochester Institute of Technology
18
Underwater Acoustic Communication
Dissipate Heat
Heat sink
Fan
Liquid cooling

Use external water

Use internal system

Image from: http://en.wikipedia.org/wiki/File:Heatsink_povray.png
10/03/13
Rochester Institute of Technology
19
Underwater Acoustic Communication
Morphological Chart
Power Converters
Transformer
Data Input
Computer
Error Detection
Parity bits
Error Correction
ARQs
(De)Compression Lossless Algorithms
(De)Encryption XOR the bit stream
Comm. Protocol
CSMA/CA
(De)Modulation
AM
Sinks Underwater Internal Weight
Water Resistant
O-Rings
Corrosion Resistant Metal Selection
Pressure Resistant
Case Design
Dissipate Heat
Heat Sink
10/03/13
Buck Converter
Auto-Generated
CRCs
FECs
Lossy Algorithms
Triple DES
Aloha
FM
External Weight
Metal-on-Metal
Coatings
Internal Presure
Fan
Rochester Institute of Technology
Linear Converter
EECs
Hybrid Scheme
AES
CDMA
Phase
Custom Design
QAM
Sealant Glue
Plastic Selection
External Liquid
20
Internal Liquid
Underwater Acoustic Communication
Pugh Analysis
Power Use
Communication Error Rate
Ease of implementation
User friendly
Cost
Probability of Catastrophic Failure
Efficiency
+'s
-'s
Power Use
Communication Error Rate
Ease of implementation
User friendly
Cost
Probability of Catastrophic Failure
Efficiency
+'s
-'s
10/03/13
Round 1
Computer
Parity
ARQs
Lossless
Triple DES
CSMA/CA
Phase
Internal Weight
Oring
Material
Case Design
Heat Sink
Datum
Datum
Datum
Datum
Datum
Datum
Datum
Round 2
Computer
Parity
ARQs
Lossless
Triple DES
CSMA/CA
Phase
Internal Weight
Oring
Material
Case Design
Heat Sink
=
=
+
=
+
2
2
Computer
Auto
Auto
Computer
Auto
Computer
CRCs
EECs
EECs
CRCs
Parity
CRC's
FECs
Hybrid
ARQs
Hybrid
FECs
ARQs
Lossy
Lossy
Lossless
Lossy
Lossy
Lossless
AES
XOR
Triple DES
AES
XOR
Triple DES
Aloha
CDMA
Custom
CSMA/CA
Aloha
CDMA
AM
FM
QAM
Phase
AM
FM
External Weight External Weight Internal Weight Internal Weight Internal Weight External Weight
Glue
M-on-M
Oring
Glue
Oring
Glue
Plastic
Coating
Galvanization
Galvanize
Coating
Material
Presurized
Presurized
Case Design
Case Design
Presurized
Case Design
Fan
Internal Liquid External Liquid
Heat Sink
Fan
Fan
=
=
=
=
+
=
=
+
=
+
=
=
+
+
+
=
+
=
=
=
=
+
+
1
0
2
2
2
2
4
5
2
2
4
2
Datum
Computer
Auto
Auto
Computer
Auto
Computer
CRCs
EECs
EECs
CRCs
Parity
CRC's
FECs
Hybrid
ARQs
Hybrid
FECs
ARQs
Lossy
Lossy
Lossless
Lossy
Lossy
Lossless
AES
XOR
Triple DES
AES
XOR
Triple DES
Aloha
CDMA
Custom
CSMA/CA
Aloha
CDMA
AM
FM
QAM
Phase
AM
FM
External Weight External Weight Internal Weight Internal Weight Internal Weight External Weight
Glue
M-on-M
Oring
Glue
Oring
Glue
Plastic
Coating
Galvanization
Galvanize
Coating
Material
Presurized
Presurized
Case Design
Case Design
Presurized
Case Design
Fan
Internal Liquid External Liquid
Heat Sink
Fan
Fan
=
Datum
=
=
=
Datum
=
+
Datum
+
=
=
+
Datum
+
=
+
Datum
+
+
Datum
+
=
Datum
+
2
0
2
3
2
4
5
4
4
0
Rochester Institute of Technology
21
Underwater Acoustic Communication
Finalized Pugh Analysis

Generation of hybrid between two best systems
Data Input
Error Detection
Error Correction
(De)Compression
(De)Encryption
Comm. Protocol
(De)Modulation
Sinks Underwater
Water Resistant
Corrosion Resistant
Pressure Resistant
Dissipate Heat
10/03/13
System 1
System 2
Hybrid System
Computer
Computer
Computer
Parity
CRC's
CRC's
ARQs
ARQs
ARQs
Lossless
Lossless
Lossless
Triple DES
Triple DES
Triple DES
CSMA/CA
CDMA
CSMA/CA
Phase
FM
Phase
Internal Weight External Weight Internal Weight
Oring
Glue
Oring
Material
Material
Material
Case Design
Case Design
Case Design
Heat Sink
Fan
Heat Sink
Rochester Institute of Technology
22
Underwater Acoustic Communication
Final System Selection
Data Input
Computer
Error Detection
CRC's
Error Correction
ARQs
(De)Compression
Lossless
(De)Encryption
Triple DES
Comm. Protocol
CSMA/CA
(De)Modulation
Phase
Sinks Underwater Internal Weight
Water Resistant
Oring
Corrosion Resistant
Material
Pressure Resistant Case Design
Dissipate Heat
Heat Sink
10/03/13
Rochester Institute of Technology
23
Underwater Acoustic Communication
Risk Analysis
ID Problem
1 The housing isn't watertight
2 Short circuit
3 Damage due to mis-handling parts
4 Loss of carrier frequency
5 Power loss
6 Power Surge
7 Data loss
8 Overheat microprocessor
9 Corrosion breach
10 Speaker doesn't work
11 Ordered components do not match specs
Likelyhood Damage Importance
Mitigation
2
3
6
Test waterproofing and test the empty housing
1
3
3
1
2
2
Team must be c areful with components
2
3
6
Have a robust communication scheme in place
1
1
1
1
3
3
Surge Protection
2
3
6
Have tested error correction/detection
1
3
3
Use efficient code and have thermal management
1
3
3
Galvanize or use corrosion resistant materials
3
3
9
Invest heavily in research & design to ensure working part
2
3
6
Order from reputable sources with return policies
Major Concerns: Speaker, Data Loss, and Carrier Frequency Loss
Minor Concerns: Power Surge, Short Circuiting, Watertight Case, and Bad Parts
10/03/13
Rochester Institute of Technology
24
Owners
SH, GD
CJ, CM
All
CJ, CM
CM
CM
JH
JH, GD
SH, GD
CJ, CM
GD
Underwater Acoustic Communication
Test Plans

ASTM B117-11 Salt Spray Test

IPX7 Submersion Testing

Operating Temperature Testing

Error Correction Testing
10/03/13
Rochester Institute of Technology
25
Underwater Acoustic Communication
Subsystem Design Schedule
10/03/13
Rochester Institute of Technology
26
Underwater Acoustic Communication
Questions?
10/03/13
Rochester Institute of Technology
27