Design of a low-cost underwater acoustic modem for short-range sensor networks

177 Pages·2010·5.63 MB·English

UC San Diego
UC San Diego Electronic Theses and Dissertations
Title
Design of a low-cost underwater acoustic modem for short- range sensor networks
Permalink
https://escholarship.org/uc/item/8j70s26c
Author
Benson, Bridget
Publication Date
2010

Peer reviewed|Thesis/dissertation
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University of California
UNIVERSITY OF CALIFORNIA, SAN DIEGO
Design of a Low-cost Underwater Acoustic Modem for Short-Range
Sensor Networks
A thesis submitted in partial satisfaction of the
requirements for the degree
Doctor of Philosophy
in
Computer Science and Engineering
by
Bridget Benson
Committee in charge:
Professor Ryan Kastner, Chair
Professor Rajesh Gupta
Professor John Hildebrand
Professor Tajana Rosing
Professor Curt Schurgers
2010
Copyright
Bridget Benson, 2010
All rights reserved.
The thesis of Bridget Benson is approved, and it is ac-
ceptable in quality and form for publication on microfilm
and electronically:
Chair
University of California, San Diego
2010
iii
DEDICATION
To everyone who told me not to give up.
iv
EPIGRAPH
Enjoy the Process
—Dr. Dan Clark
v
TABLE OF CONTENTS
Signature Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Dedication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Epigraph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Vita and Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Abstract of the Dissertation . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 2 Motivating Applications . . . . . . . . . . . . . . . . . . . . . 4
2.1 Coral Reefs . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Autonomous Drifter Swarms . . . . . . . . . . . . . . . . 7
2.3 Shallow Water Moorings . . . . . . . . . . . . . . . . . . 8
2.4 Power Utilities . . . . . . . . . . . . . . . . . . . . . . . . 10
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 3 Comparison or RF, Optical and Acoustic Communication Un-
derwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1 Radio Frequency Waves . . . . . . . . . . . . . . . . . . . 12
3.1.1 Conductivity . . . . . . . . . . . . . . . . . . . . 13
3.1.2 Wavelength . . . . . . . . . . . . . . . . . . . . . 14
3.1.3 Air/Water Interface . . . . . . . . . . . . . . . . . 15
3.1.4 Existing RF Systems . . . . . . . . . . . . . . . . 16
3.2 Optical Waves . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2.1 Physics of Optical Waves Underwater . . . . . . . 18
3.2.2 Existing Optical Systems . . . . . . . . . . . . . . 21
3.3 Acoustic Waves . . . . . . . . . . . . . . . . . . . . . . . 22
3.3.1 Absorption Loss . . . . . . . . . . . . . . . . . . . 22
3.3.2 Spreading Loss . . . . . . . . . . . . . . . . . . . 24
3.3.3 Noise . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.3.4 Passive Sonar Equation . . . . . . . . . . . . . . . 27
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3.3.5 Multipath . . . . . . . . . . . . . . . . . . . . . . 29
3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Chapter 4 Existing Underwater Acoustic Modems . . . . . . . . . . . . . 32
4.1 Commercial Modems . . . . . . . . . . . . . . . . . . . . 32
4.2 Research Modems . . . . . . . . . . . . . . . . . . . . . . 37
4.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Chapter 5 Transducer Design . . . . . . . . . . . . . . . . . . . . . . . . 42
5.1 Piezo Ceramics . . . . . . . . . . . . . . . . . . . . . . . 42
5.1.1 Type . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.1.2 Geometry . . . . . . . . . . . . . . . . . . . . . . 44
5.2 Transducer Construction . . . . . . . . . . . . . . . . . . 46
5.2.1 Wiring . . . . . . . . . . . . . . . . . . . . . . . . 47
5.2.2 Potting . . . . . . . . . . . . . . . . . . . . . . . . 47
5.2.3 Reducing Unwanted Acoustic Radiation . . . . . . 49
5.2.4 Material Costs . . . . . . . . . . . . . . . . . . . . 50
5.3 Calibration Procedures . . . . . . . . . . . . . . . . . . . 50
5.3.1 Comparison Method . . . . . . . . . . . . . . . . 50
5.3.2 Reciprocity Method . . . . . . . . . . . . . . . . . 51
5.4 Experimental Measurements . . . . . . . . . . . . . . . . 53
5.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Chapter 6 Analog Transceiver Design . . . . . . . . . . . . . . . . . . . . 58
6.1 Power Amplifier Design . . . . . . . . . . . . . . . . . . . 58
6.2 Power Management Circuit . . . . . . . . . . . . . . . . . 67
6.3 Impedance Matching Circuit . . . . . . . . . . . . . . . . 68
6.4 Pre-Amplifier Design . . . . . . . . . . . . . . . . . . . . 77
6.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Chapter 7 Digital Design . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
7.1 Modulation Schemes . . . . . . . . . . . . . . . . . . . . 81
7.2 Hardware Platforms . . . . . . . . . . . . . . . . . . . . . 85
7.3 Digital Transceiver . . . . . . . . . . . . . . . . . . . . . 87
7.3.1 Modulator . . . . . . . . . . . . . . . . . . . . . . 89
7.3.2 Digital Down Converter . . . . . . . . . . . . . . 90
7.3.3 Symbol Synchronizer . . . . . . . . . . . . . . . . 91
7.3.4 Demodulator . . . . . . . . . . . . . . . . . . . . 104
7.3.5 Clock Generation . . . . . . . . . . . . . . . . . . 105
7.3.6 HW/SW Co-Design Controller . . . . . . . . . . . 106
7.4 Resource Requirements . . . . . . . . . . . . . . . . . . . 108
7.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 110
vii
Chapter 8 System Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
8.1 Analog Testing . . . . . . . . . . . . . . . . . . . . . . . 111
8.2 Digital Testing . . . . . . . . . . . . . . . . . . . . . . . . 114
8.2.1 Hard Wired Tests . . . . . . . . . . . . . . . . . . 114
8.2.2 Bucket Tests . . . . . . . . . . . . . . . . . . . . . 118
8.3 Integrated Tests . . . . . . . . . . . . . . . . . . . . . . . 120
8.3.1 Multipath Measurements . . . . . . . . . . . . . . 120
8.3.2 Tank Tests . . . . . . . . . . . . . . . . . . . . . . 121
8.3.3 Canyon View Pool Tests . . . . . . . . . . . . . . 123
8.3.4 Westlake Tests . . . . . . . . . . . . . . . . . . . 124
8.3.5 Integrated System Test Summary . . . . . . . . . 128
8.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Chapter 9 Deployment Considerations . . . . . . . . . . . . . . . . . . . 130
9.1 Linear Programming Model . . . . . . . . . . . . . . . . 130
9.2 Battery Considerations . . . . . . . . . . . . . . . . . . . 136
9.3 Housing Considerations . . . . . . . . . . . . . . . . . . . 137
9.4 Marine Life Considerations . . . . . . . . . . . . . . . . . 138
9.4.1 Physical Effects . . . . . . . . . . . . . . . . . . . 138
9.4.2 Acoustic Effects . . . . . . . . . . . . . . . . . . . 139
9.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Chapter 10 Future Improvements . . . . . . . . . . . . . . . . . . . . . . . 141
Appendix A Bill Of Materials . . . . . . . . . . . . . . . . . . . . . . . . . 143
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
viii
LIST OF FIGURES
Figure 2.1: 2009 Sensor Deployment around Moorea . . . . . . . . . . . . . 6
Figure 2.2: Proposed Autonomous Drifter Swarm . . . . . . . . . . . . . . 7
Figure 2.3: Southern California Coastal Ocean Observing System . . . . . . 10
Figure 3.1: Electromagnetic Spectrum . . . . . . . . . . . . . . . . . . . . . 13
Figure 3.2: RF Attenuation vs. Frequency in Fresh and Sea Water . . . . . 14
Figure 3.3: RF Wavelength vs. Frequency in Sea Water, Fresh Water, and
Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 3.4: Air to Water Refraction Loss as a Function of Frequency . . . . 16
Figure 3.5: Wireless Fibre Systems SeaText Modem . . . . . . . . . . . . . 17
Figure 3.6: Absorption Coefficient of Pure Seawater . . . . . . . . . . . . . 19
Figure 3.7: The Spectral Transmittance over the upper 10m of water for
Jerlov water types . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 3.8: AcousticAbsorptionasafunctionoftemperature, pressure, and
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 3.9: Acoustic Spherical and Cylindrical Spreading Loss . . . . . . . 25
Figure 3.10: Sound Levels of Ocean Background Noises . . . . . . . . . . . 26
Figure 3.11: Source Level vs. Transmission Distance for a 40 kHz carrier an
ambient noise of 50 dB re 1 uPa at various levels of SNR . . . . 28
Figure 3.12: Ray Trace for a 40kHz source with a 15 degree beam angle
placed at 10 meters depth in a body of water 11 meters deep
with a constant sound speed of 1500 m/s . . . . . . . . . . . . . 29
Figure 5.1: (a)RawPZT,(b)PrepottedTransducer,(c)andPottedTrans-
ducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 5.2: Transducer Transmitter Voltage Response . . . . . . . . . . . . 54
Figure 5.3: Transducer Receiver Voltage Response . . . . . . . . . . . . . . 55
Figure 5.4: Transducer Figure of Merit . . . . . . . . . . . . . . . . . . . . 56
Figure 6.1: Analog Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . 59
Figure 6.2: Class A Amplifier Input/Output Characteristic . . . . . . . . . 60
Figure 6.3: Class B Amplifier Input/Output Characteristic for one transistor 61
Figure 6.4: Class AB Amplifier Input/Output Characteristic for one tran-
sistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 6.5: Block diagram of a basic switching or PWM (Class-D) amplifier 63
Figure 6.6: Block diagram of the power amplifier design making use of a
class AB and class D amplifier to achieve linearity and efficiency 63
Figure 6.7: Class AB Power Amplifier Linearity . . . . . . . . . . . . . . . 64
Figure 6.8: Complete Power Amplifier Linearity . . . . . . . . . . . . . . . 65
Figure 6.9: Power Amplifier Power Efficiency . . . . . . . . . . . . . . . . . 66
Figure 6.10: Power Management Circuit . . . . . . . . . . . . . . . . . . . . 67
ix